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  • richardmitnick 1:02 pm on April 14, 2018 Permalink | Reply
    Tags: Anita Zanella, , , , , , ESOblog,   

    From ESOblog: Women in STEM – “A Night in the Life of an Astronomer” Anita Zanella 

    ESO 50 Large

    ESOblog

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    Anita Zanella

    When most people picture an astronomer, they imagine a man in glasses peering up at the Universe through the lens of a huge telescope. While this might have been accurate a century ago, the life of a modern astronomer is a far cry from this stereotype. To learn more about what it’s like to spend a night at a telescope, we chatted to ESO Fellow Anita Zanella, who just wrapped up an observing run at ESO’s Very Large Telescope in Chile.

    Q: So Anita, tell us about your research and what you do at ESO.

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    It’s really amazing to look at these beams of light departing from inside the dome and get lost in the darkness of the night sky.
    ____________________________________________________________

    A: I’m an ESO Fellow who studies distant galaxies, trying to understand how they form and evolve through cosmic time. I’m interested in questions like: how are stars born inside galaxies? Why do some galaxies keep forming stars while others stop? Why are galaxies shaped like they are, and how does it change over time?

    I’m enjoying my time at ESO very much because it allows me to undertake my own research, but also discover so many other sides of astronomy that I did not even imagine: how observations are performed, how an observatory is run, how instruments are conceived of and built, how proposals of observations are evaluated and chosen, and so much more. It also allows me to meet and work with people from very different backgrounds, not just astronomers but also people such as instrument scientists and engineers, which is very enriching and mind-opening.

    Another cool thing is that as part of my fellowship, I have to spend 40 nights at the Paranal Observatory in Chile each year. I’m based at ESO Headquarters in Germany, so it takes a long time to reach Paranal — it’s almost a two-day trip! So I decided to have 14-night shifts, meaning I go to Chile three times a year.

    Glistening against the awesome backdrop of the night sky above ESO_s Paranal Observatory, four laser beams project out into the darkness from Unit Telescope 4 UT4 of the VLT.

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    Taken from inside the dome of the fourth Unit Telescope of ESO’s Very Large Telescope (VLT), this spectacular shot captures the VLT’s Laser Guide Star (LGS) in action
    Credit: Y. Beletsky (LCO)/ESO

    Q: What is your daily (or rather, nightly) timetable like?

    A: One of the things I really like about observing is that everything depends on nature — not only when and what to observe, but also the daily schedule of people working at the observatory. Night astronomers work every day, from sunset to sunrise. Two and a half hours before sunset we have a meeting where the daytime crew summarises what work has been done to maintain or repair the telescopes, the status of the various instruments, and what needs to be finished in the remaining hours before sunset. At that meeting, night astronomers specify what instrument they need at the beginning of the night and when they need to start observing.

    So usually I get up in the afternoon a few hours before sunset, grab a quick breakfast, and go to the afternoon meeting. It takes place in the control building, on top of the mountain just below where the telescopes are, but we sleep in the Residencia, a wonderful building, located a couple of kilometres from the telescopes. During the Chilean winter (from June to August) nights are very long, so I travel to the control building by car in about five minutes. But during the Chilean summer (from November to January) nights are short, so I usually get up early enough to have the time to hike to the meeting on the so-called “star track”, a steep path that takes you up to the control building in about 45 minutes. I love walking there, listening to the silence of the desert, watching how the shades and colours change during the day. Sometimes I can also see small animals: a lizard, a bird, some insects…

    After the meeting, we have dinner (or lunch, depending on your perspective!) at the Residencia and drive up to the mountain once again to be in control building a few minutes before sunset. Every time I can, I enjoy looking at the Sun disappearing into the ocean on the horizon, while the sky around becomes orange and pink. It is a show that never ceases to amaze me. And for the first time during my last shift, I also saw the famous green flash: it is not a legend, it’s real!

    Often we have calibrations to make at the beginning of the night. Some of them can be started about half an hour before sunset so the daytime crew takes care of them, while others have to be taken in twilight so the night astronomer is responsible for them. What time the dome first opens depends on the calibrations, but at latest it’s sunset — then the telescopes are ready to observe. Infrared observations can actually be carried out during the evening twilight, as soon as the first stars are visible, and can be used to guide the telescope in order to correct for the rotation of the Earth. Similarly, we can keep observing in the infrared in the morning twilight. But for observations at optical wavelengths, we need full dark so we have to wait for the end of twilight before observing.

    Then half an hour before sunrise, the telescope’s dome has to be closed. The daytime crew arrives at the top of the mountain, where they start their day with a meeting, to check if anything did not function during the night and agree on what needs to be done that day. But at this point, the telescope operators and night astronomers are already in bed!

    Q: Are you working the whole time, or are there times when you’re waiting around?

    A: Often, the observations last for one hour, so while I wait I usually plan what to observe afterwards, or I assess the data taken previously. I’m also always monitoring the current observations, making sure they’re running to plan. In case of bad weather (like if the humidity is above 70% or the wind is stronger than 18 metres per second), we have to close the dome, so I usually just go on with my own research. Of course, from time to time I take a break and go outside to look at the sky with my own eyes: to me, it is always more magical than looking at it through a screen!

    Q: The sky must look amazing without light pollution. Do you also have to keep the observatory dark during the night?

    A: Yes! As soon as sunset is over, blackout blinds are put over the windows in the control room, so artificial light does not pollute the observations. Similarly, blinds cover the windows of the Residencia. From this moment on, astronomers can only use torches if they walk outside, and cars have to keep their lights off. If there is full Moon it is still relatively easy to see the road and even distinguish shapes in the desert, but when the Moon is not there, the darkness is complete. The small artificial lights that help drivers to see the road are really necessary because otherwise the desert is completely swallowed by the night. At that point, the stars above us are the only source of light and it is always amazing for me to stay outside and stare at them.

    Q: Can you leave the control room once you’ve begun your shift?

    A: Well there are always at least two people at each telescope — one night astronomer and one telescope operator — and there are six consoles (or workstations) in the control room at Paranal: four for the UTs, one shared between the two survey telescopes (VST and VISTA), and one for the VLTI. So there are at least twelve people in the control building, plus visiting astronomers and trainees too. The atmosphere is always very pleasant and often funny, chatting and joking.

    Someone always has to stay at the telescope to check that everything is working properly, which means you’ll always find either the telescope operator or the night astronomer sitting in front of the console. From time to time we leave the control building to take a short walk on the platform where the telescopes are to look at the night sky, or to take visitor astronomers back to the Residencia when they have finished their observations, or to have dinner. (Eating is the last worry in Paranal — food is always available at any time of the day and night!)

    Also, sometimes astronomers are required to work on other projects during the day, so they only have to remain at the telescope until 3 am. In this case, they prepare a queue of observations for the rest of the night and the telescope operator is in charge of carrying them out. Telescope operators always have to stay for the full night, as they are the only ones allowed to move the telescopes. They are very precious because they have an incredible knowledge of how to operate telescopes and instruments!


    A 360-degree panorama of the Control Room, inside the control building, at night: when the action takes place
    Credit: ESO

    Q: Do you also get the chance to make observations for your own research?

    A: Usually I make observations for other astronomers who request them through proposals, but I was once able to observe targets for my own research. The experience was much more intense than observing for others, and it was really special to go through the whole process of conceiving an idea, writing it down in a proposal, having it accepted, taking the data at the telescope, and then using them! It was really thrilling to be at the telescope, waiting for the first image to arrive and immediately seeing if it was what I expected!

    _______________________________________________________________
    These telescopes and instruments are so complex and made of so many different pieces that it is very normal that sometimes something goes wrong.
    _______________________________________________________________

    Q: You said that the daytime crew keeps telescopes and instruments running smoothly, but what happens if something goes wrong during the night?

    A: It may happen that during the night something fails! These telescopes and instruments are so complex and made of so many different pieces that it is very normal that sometimes something goes wrong. Actually, I find it a miracle that everything keeps working smoothly almost every night! So, if something goes wrong during the observations, the night astronomer and the telescope operator leave a message for the daytime crew, who usually fix the issues the next day and the observatory is ready to go again by sunset.

    Q: The length of the night changes from summer to winter — does this affect your observations?

    A: I knew that nights in the winter are longer than in the summer, but realising it at the telescope is a whole different experience and I will never forget it! In the summer nights are short and the twilight is long, so of course, we can observe less, but we can sleep longer during the day and I usually also manage to take some time for myself — for example, taking a walk. In the winter it’s the opposite: sometimes nights are so long they become exasperating!

    On one hand, I like them, because I manage to take many observations and I feel that a lot of science is coming out of the observatory. But on the other hand, the available hours of sleep are barely enough to get enough fresh energy for the coming night, and I usually don’t manage to do anything else except observe, sleep, and eat. After 14 nights it gets a bit exhausting — but very satisfying.

    Surprisingly, it’s more difficult for me to adjust to the season change, especially when I come back from the Chilean summer (+30°C) to the German winter (-10°C). My body gets confused and it takes me a week to get used to the cold again. Switching from cold to warm weather is actually way easier for me…but I have to admit that I am a real fan of summertime!

    Q: What is your favourite part of working at Paranal?

    A: There are so many things that I like about Paranal! I always enjoy being amazed by the night sky, as well as by sunsets and sunrises. I also like to hike in the desert, watching how colours and the light change, stopping from time to time to look at the ocean on the horizon. I still find it amazing that we can see water from the top of a mountain, in the middle of the driest desert in the world! I really like to lie outside sometimes, stopping to breathe for a while and just listen to the silence of the desert.

    I like the working environment of Paranal as well: people really cooperate and work together to get this incredible observatory to function every night. They are always available to help and happy to share their knowledge, to teach you and show you around. I like the enthusiasm. It always gives me a lot of energy!

    Finally, I always find observing itself quite thrilling, waiting for the images to appear on the monitor and having the impression that science is flowing through the telescope!

    See the full article here .

    Please help promote STEM in your local schools.
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    ESO is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive ground-based astronomical observatory by far. It is supported by 16 countries: Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Poland, Portugal, Spain, Sweden, Switzerland and the United Kingdom, along with the host state of Chile. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope, the world’s most advanced visible-light astronomical observatory and two survey telescopes. VISTA works in the infrared and is the world’s largest survey telescope and the VLT Survey Telescope is the largest telescope designed to exclusively survey the skies in visible light. ESO is a major partner in ALMA, the largest astronomical project in existence. And on Cerro Armazones, close to Paranal, ESO is building the 39-metre European Extremely Large Telescope, the E-ELT, which will become “the world’s biggest eye on the sky”.

    ESO LaSilla
    ESO/Cerro LaSilla 600 km north of Santiago de Chile at an altitude of 2400 metres.

    ESO VLT
    VLT at Cerro Paranal, with an elevation of 2,635 metres (8,645 ft) above sea level.

    ESO Vista Telescope
    ESO/Vista Telescope at Cerro Paranal, with an elevation of 2,635 metres (8,645 ft) above sea level.

    ESO NTT
    ESO/NTT at Cerro LaSilla 600 km north of Santiago de Chile at an altitude of 2400 metres.

    ESO VLT Survey telescope
    VLT Survey Telescope at Cerro Paranal with an elevation of 2,635 metres (8,645 ft) above sea level.

    ALMA Array
    ALMA on the Chajnantor plateau at 5,000 metres.

    ESO E-ELT
    ESO/E-ELT to be built at Cerro Armazones at 3,060 m.

    ESO APEX
    APEX Atacama Pathfinder 5,100 meters above sea level, at the Llano de Chajnantor Observatory in the Atacama desert.

    Leiden MASCARA instrument, La Silla, located in the southern Atacama Desert 600 kilometres (370 mi) north of Santiago de Chile at an altitude of 2,400 metres (7,900 ft)

    Leiden MASCARA cabinet at ESO Cerro la Silla located in the southern Atacama Desert 600 kilometres (370 mi) north of Santiago de Chile at an altitude of 2,400 metres (7,900 ft)

    ESO Next Generation Transit Survey at Cerro Paranel, 2,635 metres (8,645 ft) above sea level

    SPECULOOS four 1m-diameter robotic telescopes 2016 in the ESO Paranal Observatory, 2,635 metres (8,645 ft) above sea level

    ESO TAROT telescope at Paranal, 2,635 metres (8,645 ft) above sea level

    ESO ExTrA telescopes at Cerro LaSilla at an altitude of 2400 metres

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  • richardmitnick 1:53 pm on April 9, 2018 Permalink | Reply
    Tags: , , , , , ESOblog, Mapping the Universe in 3D   

    From ESOblog: “Mapping the Universe in 3D” 

    ESO 50 Large

    ESOblog

    ESO’s telescopes are used to study everything from the tiny dust particles spinning around distant suns to the large-scale structure of galaxies. The Very Large Telescope has recently undertaken a massive project called the VIMOS Public Extragalactic Redshift Survey (VIPERS), which catalogued 90 000 galaxies and measured their distribution as it was between five and eight billion years ago. To find out more, we interviewed Luigi Guzzo, Professor of Cosmology at the University of Milano, who led the VIPERS team.

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    The large-scale distribution of galaxies as it was between 5 and 8 billion years ago, unveiled by the nearly 90,000 new galaxy distances mapped by the VIPERS project.
    Some of the first spectra of distant galaxies obtained with VIMOS, where more than 220 galaxies were observed simultaneously. The light from each galaxy passes through the dedicated slit in the mask and produces a spectrum on the detector; each vertical rectangle contains the spectrum of one galaxy that is located several billion light-years away. These spectra allow astronomers to obtain the redshift, a measure of distance, as well as to assess the physical status of the gas and stars in each of these galaxies.
    Credit: ESO

    VIPERS FACTS
    The “VIMOS Public Extragalactic Redshift Survey” (VIPERS) is a completed ESO Large Program that has mapped in detail the spatial distribution of normal galaxies over an unprecedented volume of the z~1 Universe. It used the VIMOS spectrograph at the 8~m Very Large Telescope to measured spectra for more than 90,000 galaxies with red magnitude I(AB) brighter than 22.5 over an overall area of nearly 24 square degrees. At this redshift, VIPERS fills a unique niche in galaxy surveys, optimizing the combination of multi-band accurate photometry (5 bands from the CFHT-LS, plus Galex-NUV and NIR from WIRCAM and other facilities over most of the area) with the multiplexing capability of VIMOS. A robust color-color pre-selection allowed the survey to focus on the 0.5 < z < 1.2 redshift range, yielding an optimal combination of large volume (5 x 107 h-3 Mpc3) and high effective spectroscopic sampling (46% on average). VIPERS has produced a data set that in many respects represents for the first time the equivalent at z~1 of the large surveys of the "local" (z<0.2) Universe built at the beginning of this century (SDSS and 2dFGRS).

    VIPERS scientific investigations are focusing on measurements of large-scale structure and cosmological parameters at an epoch when the Universe was about half its current age. At the same time, the survey is exploring the ensemble properties of galaxies with unprecedented statistical accuracy at these redshifts, providing the natural extension back in time to classical results from the SDSS.

    Q: Why is cosmology so exciting to you?

    A: Ever since I was a kid, nature and the way things work have always fascinated me. This desire to understand how things work, at the deepest level, meant I would eventually become interested in either the very small or the very big. I ended up fascinated by the incredibly big: astronomy, in general, but mainly cosmology, which is related to the origins of everything, to the earliest questions in the Universe. It is connected to where the Universe comes from and how things originated from its homogenous initial state.

    Q: Tell us about the VIPERS project. What was the initial aim?

    A: VIPERS is a redshift survey, meaning we do a very simple thing: measure the distances of many, many galaxies to reconstruct their 3D distribution in a given volume of space. We have a way to reconstruct these distances because the Universe is quite kind to us: it’s expanding, and the apparent speed of expansion (which we see in the spectrum of each galaxy) is directly connected to the galaxy’s distance from us. The more distant galaxies are, the more rapidly they fly away from us, so the light we see from these galaxies is shifted towards the red. Thanks to this property of the Universe, we can get an approximation of their distance.

    VIPERS is the last in a series of deep surveys that began when VIMOS, the spectrograph at ESO’s VLT, was built at the end of the 1990s. VIMOS is very efficient, capable of collecting different spectra for 400–500 objects at the same time.

    Q: How do you measure the redshift of these galaxies?

    A: Essentially you take the light from galaxies or stars and send it through a spectrograph. A spectrograph is just a prism that splits light into colours like a rainbow. It shows you that in the spectra of stars and galaxies there are hydrogen lines, oxygen lines, iron lines, and so on — the same chemical elements that we know on Earth. These emission or absorption lines have a specific position and a specific wavelength, but decades ago astronomer Edwin Hubble and collaborators noticed that when looking at the spectra of other galaxies, the positions of these lines were moved, shifted towards the red. They also noticed that this shift was higher for more distant galaxies — and this is actually how the expansion of the Universe was discovered.

    Q: Why did you choose to catalogue 90 000 galaxies?

    A: Usually astronomers have to make compromises between their grand scientific aims and what the instrument they’re using actually allows them to do. VIMOS is very special in this respect because there is no other spectrograph in the world that allows you to have the same combination of area of the spectrograph and density of objects that you can observe simultaneously. This makes VIMOS ideal to do these surveys in the distant Universe.

    We chose to survey 90 000 galaxies in order to cover a volume comparable to the volumes we observed at the smaller redshifts (that is, nearby), because we wanted to compare the statistics. We wanted to look over as large a volume of space as possible, but we still wanted the galaxies to be close enough together to allow us to see the details of galactic structures. So we compromised at 90 000.

    Q: So what did this survey tell us about the Universe?

    A: We actually learned a lot about Einstein’s theory of general relativity, which is something we thought about when we proposed the VIPERS project. Galaxies tend to move towards regions of higher density, so, in some way, these galactic motions reflect the growth of the structure of the Universe. As time passes this structure keeps condensing, so when you measure the redshift, you are including this little velocity component that actually contains information about the dynamics of the Universe — and you can use it to determine how quickly these structures grow. In other words, it is a way to test the theory of relativity.

    So, if you have modifications of general relativity on a very large scale, these could be “visible” in the way galaxies assemble. One way to explain such modifications is to include them in the equations of general relativity: as what Einstein called the cosmological constant. We don’t yet understand the origin of this constant, and since it is so difficult to understand in terms of theoretical physics, people started thinking that perhaps it’s not the right solution, perhaps you have to modify general relativity at large scales. This was one of the driving ideas for VIPERS. We presented four measurements of the growth of structure, using four different techniques from the same data, which we published over the past year.

    Q: So what were the main conclusions of the survey?

    A: Essentially all of our measurements are consistent with general relativity. With VIPERS we could see how different types of galaxies trace the structure. For example, we discovered that if we used the luminous blue galaxies, then the measurements of this growth rate are more accurate and less biased.

    Unexpectedly, this survey also allowed us to measure cosmic voids — the spaces between large-scale galactic structures. By looking at cosmic voids with VIPERS, we could see the way galaxies flow away from these voids, because voids are underdense regions, so the galactic structures around them tend to squeeze.

    Equally important, I think, were our results on galaxy evolution. These are really outstanding — by combining VIPERS and the existing Sloan Digital Sky Survey data of the local Universe, we could cover 9 billion years of evolution to see how galaxies transform from the early Universe to today.

    We saw how galaxies change their colour over time. Back in the earlier Universe, we saw a fraction of massive blue galaxies (meaning they are young, active, and still forming stars) which are no longer around today. They’ve become red as they grow older, so the number of red massive galaxies grows while the number of blue massive galaxies declines. That’s a very important result.

    What’s really amazing is that even though we observed 90 000 galaxies, VIPERS was only conducted in 440 hours of observing time. The amount of information it produced is incredible.


    The positions in space of the galaxies identified by the VIPERS survey. This “slice” through the Universe shows where the galaxies lie as we look to ever greater distances in space — corresponding to looking further back in time. Data like these allow astronomers to study the evolution of galaxies as a constituent of the Universe, and tell us about how space itself evolves over time.
    Credit: S. Arnouts, N. Malavasi & the VIPERS Collaboration

    Q: Did you learn any new techniques that might be useful for other projects or fields?

    A: Definitely. What we learned about the instrumentation and the data reduction is now going to be used for a big project of the European Space Agency called Euclid, a space telescope with a spectrograph and an imager on board that will be launched in 2021. My team is involved in the spectroscopic part of the project — which is very different and much more complicated to use than VIMOS, but our work on VIPERS with VIMOS will help us when looking at data from Euclid.

    Q: Is there anything left to do on the VIPERS project?

    A: There are a few more papers in preparation, where we look at more specific details, in particular on the galactic evolution side. In terms of cosmology, I think it is basically done — but our dataset is still a great playground for people who want to test new methods, and we hope the sample will be used a lot by other people with smart ideas, who may find something unexpected. That’s the beauty of these large redshift surveys: the discovery space that you open.

    As a final note, I just want to add that the support from the ESO staff to this project has been really great. One of the reasons why the project went well was because they supported us and always responded promptly to our request and questions.

    The VIMOS Public Extragalactic Redshift Survey (VIPERS)⋆An unprecedented view of galaxies and large-scale structure at 0.5 < z < 1.2. Astronomy and Astrophysics

    The VIMOS Public Extragalactic Redshift Survey (VIPERS)Full spectroscopic data and auxiliary information release (PDR-2)⋆ Astronomy and Astrophysics

    Biography Luigi Guzzo

    Luigi Guzzo is Professor of Cosmology at the University of Milano. He is a cosmologist, interested in observing and modelling the large-scale structure of the Universe. Over the past decade he has led the VIMOS Public Extragalactic Redshift Survey (VIPERS) with the ESO VLT and he is now one of the core science coordinators of the ESA mission Euclid, a space telescope to map the dark and luminous Universe, due to launch in 2021. In 2012 he has received an Advanced Grant from the European Research Council (ERC), a five-year financial contribution that sustained the development of new analysis methods and their application to VIPERS and other surveys.

    See the full article here .

    Please help promote STEM in your local schools.
    STEM Icon

    Stem Education Coalition
    Visit ESO in Social Media-

    Facebook

    Twitter

    YouTube

    ESO Bloc Icon

    ESO is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive ground-based astronomical observatory by far. It is supported by 16 countries: Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Poland, Portugal, Spain, Sweden, Switzerland and the United Kingdom, along with the host state of Chile. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope, the world’s most advanced visible-light astronomical observatory and two survey telescopes. VISTA works in the infrared and is the world’s largest survey telescope and the VLT Survey Telescope is the largest telescope designed to exclusively survey the skies in visible light. ESO is a major partner in ALMA, the largest astronomical project in existence. And on Cerro Armazones, close to Paranal, ESO is building the 39-metre European Extremely Large Telescope, the E-ELT, which will become “the world’s biggest eye on the sky”.

    ESO LaSilla
    ESO/Cerro LaSilla 600 km north of Santiago de Chile at an altitude of 2400 metres.

    ESO VLT
    VLT at Cerro Paranal, with an elevation of 2,635 metres (8,645 ft) above sea level.

    ESO Vista Telescope
    ESO/Vista Telescope at Cerro Paranal, with an elevation of 2,635 metres (8,645 ft) above sea level.

    ESO NTT
    ESO/NTT at Cerro LaSilla 600 km north of Santiago de Chile at an altitude of 2400 metres.

    ESO VLT Survey telescope
    VLT Survey Telescope at Cerro Paranal with an elevation of 2,635 metres (8,645 ft) above sea level.

    ALMA Array
    ALMA on the Chajnantor plateau at 5,000 metres.

    ESO E-ELT
    ESO/E-ELT to be built at Cerro Armazones at 3,060 m.

    ESO APEX
    APEX Atacama Pathfinder 5,100 meters above sea level, at the Llano de Chajnantor Observatory in the Atacama desert.

    Leiden MASCARA instrument, La Silla, located in the southern Atacama Desert 600 kilometres (370 mi) north of Santiago de Chile at an altitude of 2,400 metres (7,900 ft)

    Leiden MASCARA cabinet at ESO Cerro la Silla located in the southern Atacama Desert 600 kilometres (370 mi) north of Santiago de Chile at an altitude of 2,400 metres (7,900 ft)

    ESO Next Generation Transit Survey at Cerro Paranel, 2,635 metres (8,645 ft) above sea level

    SPECULOOS four 1m-diameter robotic telescopes 2016 in the ESO Paranal Observatory, 2,635 metres (8,645 ft) above sea level

    ESO TAROT telescope at Paranal, 2,635 metres (8,645 ft) above sea level

    ESO ExTrA telescopes at Cerro LaSilla at an altitude of 2400 metres

     
  • richardmitnick 3:50 pm on April 1, 2018 Permalink | Reply
    Tags: , , , , ESOblog, Polaris star system, Richard I. Anderson   

    From ESOblog: “Probing Polaris” 

    ESO 50 Large

    ESOblog

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    Science@ESO

    30 March 2018

    While most people have heard of the North Star and may even be able to find it in the night sky at the north celestial pole, it remains the fascinatingly curious subject of many astronomers’ gaze. This week we speak to astronomer and ESO Fellow Richard I. Anderson, who has been carefully studying Polaris and coming to terms with a seemingly insurmountable problem the famous star poses.

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    Richard I. Anderson.

    Q: Tell us about Polaris. Why is it so interesting?

    A: Polaris, also known as the North Star, is too far north to be seen with any of ESO’s telescopes from Chile, but those in the northern hemisphere can easily find it in the sky as the brightest star in the constellation of Ursa Minor (the Little Bear). For a long time, it played a crucial role in human navigation since it always allows those in the northern hemisphere to find north. But most people don’t know just how interesting Polaris truly is. It’s actually a multiple system consisting of three stars: Polaris Aa, which is a Cepheid variable and the subject of my research, and Polaris Ab and Polaris B, which are both main sequence stars much like our Sun. Importantly, it is the Cepheid Polaris Aa that we see with the naked eye (Polaris Ab and B are more than 500 times fainter).

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    This picture shows the constellations of Ursa Major, Ursa Minor and Polaris, plus the portion of sky studied in the All-Wavelength Extended Groth Strip International Survey (AEGIS). Credit: NASA/ESA, The Hubble Heritage Team and A. Riess (STScI).

    Q: What are Cepheid variable stars?

    A: Cepheids are a class of pulsating stars that exhibit periodic changes in brightness, diameter, and temperature. As they grow and shrink, their temperature changes, making the colour of the star vary from yellow to red. The timescale for these variations ranges from a couple of days to a couple of months, and the brightness changes are so significant that they can be detected by eye — as first discovered by the English astronomer John Goodricke in 1784.

    Stars change very slowly (we say “evolve”) over millions to billions of years because they slowly use up the source of energy at their cores. The structure of stars thus changes slowly with time. Some stars — those between 3–10 times our Sun’s mass — can become Classical Cepheid variables later on in their lives, when small perturbations grow larger and larger until the entire star starts to oscillate. Polaris is such a variable star, more specifically a Classical Cepheid.

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    This sequence of images taken with the Hubble Space Telescope chronicles the rhythmic changes in a rare class of variable star (located in the centre of each image) in the spiral galaxy Messier 100. This class of pulsating star is called a Cepheid Variable. This doubles in brightness over a period of 51.3 days. Credit: NASA/ESA Hubble Space Telescope/W. L. Freedman (Observatories of the Carnegie Institution of Washington)

    Q: Why are Cepheid variables like Polaris so important in astrophysics?

    A: Cepheids are extremely important for two main reasons:

    Firstly, they allow us to determine accurate distances to far away galaxies. Cepheids are so-called standard candles: objects whose true brightness we can calculate based on their period (the time it takes for a star to go from bright to dim). We calculate this through a relationship called Leavitt’s Law. Comparing the true brightness with how bright a Cepheid appears in the sky means astronomers can figure out how far away the star and its host galaxy are — similar to a candle that appears dimmer the farther away it is. This is crucial in cosmology, forming the basis of the cosmic distance ladder that we use to measure how fast the Universe is currently expanding. Not surprisingly, Cepheids are the subject of much research in order to achieve the most accurate measurement of the Hubble constant and to learn about the elusive dark energy.

    Cepheids are also important because their light variations provide insights into the internal structure of stars in an advanced stage of stellar evolution. Understanding how stars evolve is extremely important to all of astrophysics, helping us understand how galaxies evolve, how the building blocks of life came about (since oxygen, nitrogen, and carbon are created inside stars), and many other subjects. Theoretical models are needed to learn about these things. Such models provide very different predictions for evolved stars depending on the assumptions we put into them — we don’t understand them as well as we understand younger stars. These evolved stars are therefore sensitive laboratories for astronomers to learn about stellar evolution.

    For example, an important question in stellar astrophysics is how the rotation of a star around its own axis affects its evolution. Theory predicts that rotation should mix the outer layers of stars in a certain way, and the results of this mixing will show more clearly in the later stages of evolution — such as when stars become Cepheids. This means that rotation can change the surface composition of stars over time. For example, a high ratio of nitrogen to carbon and oxygen is like a smoking gun for stellar rotation.

    Incredibly, in Cepheids we can see stellar evolution taking place on human timescales because we can observe slow changes in the duration of their light variations! This allows us to pinpoint the phase of stellar evolution a Cepheid currently is in. Measuring the chemical composition of a Cepheid’s surface can therefore tell us a lot about how stars evolve in general, and how rotation affects their evolution.

    4
    Observing Cepheid variables can help astronomers determine relatively short distances in the Universe. Such distance measurements help astronomers calculate how fast the universe expands with time, called the Hubble constant. Credit: NASA, ESA, A. Feild (STScI), and A. Riess (STScI/JHU).

    Q: Why is Polaris Aa a particularly interesting Cepheid to study?

    A: One reason is the uncertainty about its distance — the distance to Polaris has been revised repeatedly by researchers. A recent measurement by Bond et al [The Astophysical Journal]. using the NASA/ESA Hubble Space Telescope placed Polaris at the greatest distance yet, at about 520 light-years away. Remember that Polaris is a multiple star system — and yet the new distance measurement by Hubble was actually based only on observations of Polaris B. The Cepheid, Polaris Aa, would simply have been too bright for Hubble to observe.

    Polaris Aa is also interesting because of its peculiar behaviour, including changes in the size and duration of its light variations — these have puzzled astronomers for a long time. Additionally, given the controversy of its distance in the past, we hadn’t been able to really figure out its evolutionary stage and other properties. Mind you, this is the closest Cepheid from Earth, so we naturally want to be able to understand it.

    What particularly fascinates me is that when this new distance for Polaris B is assumed to be true for Polaris Aa as well, we arrive at an interesting conundrum.

    5
    This sequence of images shows that the North Star, Polaris, is really a triple star system. Credit: NASA, ESA, N. Evans (Harvard-Smithsonian CfA), and H. Bond (STScI).

    A: In my paper, I show that we can finally understand the properties and evolutionary stage of Polaris Aa in unprecedented detail if we use the distance to Polaris B as its distance. The two are very close in the sky and seem to be moving together, so it’s been commonly assumed that the two stars are genuinely at the same distance, gravitationally bound to each other. Moreover, the extremely detailed agreement between theoretical predictions and several independent, highly sensitive observational results shown in my paper renders this assumption a virtual certainty.

    But if the two stars are indeed gravitationally bound, then they should have been born at the same time. This leads to an insurmountable problem: the Cepheid Polaris Aa must be a young star about 50 million years old, whereas B is a relatively old star at two billion years old. This raises very big questions about how these two very differently-aged stars came to be such intertwined companions.

    My paper gives some suggestions for the causes of this age discrepancy, but I haven’t yet found a resolution. For this reason, I have jokingly referred to this case as the “Polaris Uncertainty Principle”: the better you reproduce the properties of the North Star from theory, the less you understand why you managed to do it!

    This is an artist’s impression showing a view from within the Polaris triple star system.
    Credit: NASA, ESA, G. Bacon (STScI)

    Q: So how did you arrive at these results?

    7
    This is an artist’s impression showing a view from within the Polaris triple star system. Credit: NASA, ESA, G. Bacon (STScI).

    A: This age problem has been noted before, but I’ve now confirmed it by comparing observations of Polaris with the Geneva stellar evolution models, which make predictions about stellar evolution that incorporate the effects of a star’s rotation. All stars rotate and yet many researchers still use models that leave out this crucial effect because modelling rotation is difficult and involves a lot of unknowns. I’ve been very interested in using Cepheid variables to test these theoretical models and see where they fail.

    I compared theoretical predictions from Geneva stellar evolution models to observations previously made of Polaris Aa. The results show incredibly detailed agreement between the two, including the rate of period change, Leavitt’s law, Polaris Aa’s colour and brightness, its radius, the abundance of nitrogen in its surface compared to carbon and oxygen, and its mass. Such detailed agreement is very rare for any evolved star, and it strongly supports the assumption that Polaris Aa and B really are at the same distance.

    When I suddenly realised that the Geneva models provided a very consistent picture of the evolutionary status of Polaris, bypassing some of the difficulties encountered by other authors, I was extremely surprised and excited. The best part was that the model predictions that specifically depend on rotation almost exactly matched the observed values! This was a huge success for the models.

    Q: What else was exciting about this research?

    A: On one hand it was the speed with which things happened. I began this work on 22 December last year in response to the paper by Bond et al. mentioned above, and by that same evening, I knew that it was worth writing a follow-up paper of my own. After discussing the result with colleagues at ESO when we returned from Christmas break, I was ready to submit before the end of the first week of January.

    On the other hand, there is this interesting juxtaposition: we had arrived at an incredibly detailed understanding of such an important star, and yet how Polaris B and Aa came to be companions is still a puzzle. This pair cannot be explained using standard stellar evolution theory, and not even by a merger in a binary system!

    Another nice element is that I have been looking at this star since I was a child, observing it with the naked eye from my bedroom window. And now all of a sudden, I know so much about this object. To me, that is the true wonder of astronomy: making sense of the things that are so far out of our reach and yet we nonetheless relate to them at a very basic level.

    Q: What’s next? How might we understand how Polaris B and Aa came together?

    A: A promising route is to simulate how star clusters and multiple star systems evolve together, taking into account the dynamics of their gravitational interactions. If the Polaris system is the remaining core of a star cluster that has since dispersed because of dynamical interactions, then it might be possible to explain the age discrepancy between Polaris Aa and B via such interactions and stars that may have merged. I’ve recently initiated a new collaboration with researchers from Bonn to better understand this dynamical picture.

    Q: How does this result fit into the big picture of your research area?

    A: My research aims to address two fundamental questions of astrophysics: Understanding how rotation affects the evolution of stars and enabling a highly accurate measurement of the expansion rate of the Universe (the Hubble constant).

    With this result, I’ve shown the exceptional agreement between stellar evolution models that include the effects of rotation and Polaris, a star that has long thwarted a detailed explanation. One of the key pieces of evidence for rotation — the abundances of nitrogen, carbon and oxygen in the stellar surface — was spot-on. This is a big success for these stellar evolution models, and I plan to keep testing these models with observational data.

    I’m also currently working on larger numbers of Cepheids that are used to calibrate the cosmic distance scale. Specifically, I work on the effects that companion stars and star clusters have on the calibration of the Leavitt’s law. Understanding these effects — and correcting for them — will be an important step for measuring the Hubble constant with the accuracy required to better understand dark energy.

    See the full article here .

    Please help promote STEM in your local schools.
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    ESO is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive ground-based astronomical observatory by far. It is supported by 16 countries: Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Poland, Portugal, Spain, Sweden, Switzerland and the United Kingdom, along with the host state of Chile. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope, the world’s most advanced visible-light astronomical observatory and two survey telescopes. VISTA works in the infrared and is the world’s largest survey telescope and the VLT Survey Telescope is the largest telescope designed to exclusively survey the skies in visible light. ESO is a major partner in ALMA, the largest astronomical project in existence. And on Cerro Armazones, close to Paranal, ESO is building the 39-metre European Extremely Large Telescope, the E-ELT, which will become “the world’s biggest eye on the sky”.

    ESO LaSilla
    ESO/Cerro LaSilla 600 km north of Santiago de Chile at an altitude of 2400 metres.

    ESO VLT
    VLT at Cerro Paranal, with an elevation of 2,635 metres (8,645 ft) above sea level.

    ESO Vista Telescope
    ESO/Vista Telescope at Cerro Paranal, with an elevation of 2,635 metres (8,645 ft) above sea level.

    ESO NTT
    ESO/NTT at Cerro LaSilla 600 km north of Santiago de Chile at an altitude of 2400 metres.

    ESO VLT Survey telescope
    VLT Survey Telescope at Cerro Paranal with an elevation of 2,635 metres (8,645 ft) above sea level.

    ALMA Array
    ALMA on the Chajnantor plateau at 5,000 metres.

    ESO E-ELT
    ESO/E-ELT to be built at Cerro Armazones at 3,060 m.

    ESO APEX
    APEX Atacama Pathfinder 5,100 meters above sea level, at the Llano de Chajnantor Observatory in the Atacama desert.

    Leiden MASCARA instrument, La Silla, located in the southern Atacama Desert 600 kilometres (370 mi) north of Santiago de Chile at an altitude of 2,400 metres (7,900 ft)

    Leiden MASCARA cabinet at ESO Cerro la Silla located in the southern Atacama Desert 600 kilometres (370 mi) north of Santiago de Chile at an altitude of 2,400 metres (7,900 ft)

    ESO Next Generation Transit Survey at Cerro Paranel, 2,635 metres (8,645 ft) above sea level

    SPECULOOS four 1m-diameter robotic telescopes 2016 in the ESO Paranal Observatory, 2,635 metres (8,645 ft) above sea level

    ESO TAROT telescope at Paranal, 2,635 metres (8,645 ft) above sea level

    ESO ExTrA telescopes at Cerro LaSilla at an altitude of 2400 metres

     
  • richardmitnick 12:28 pm on March 24, 2018 Permalink | Reply
    Tags: , , , , ESOblog, Shooting for the Stars   

    From ESOblog: “Shooting for the Stars” 

    ESO 50 Large

    ESOblog

    1
    Science Snapshots

    23 March 2018

    ESO’s role in the revolutionary Breakthrough Initiatives.

    Our fragile blue planet circles a star that is just one of hundreds of billions in our galaxy — which itself is just one stellar neighbourhood in a vast Universe of at least a hundred billion more. Astronomers, science fiction writers and the public alike have all long wondered: Are we alone in the cosmos? ESO recently joined the search for habitable worlds around other stars in collaboration with the Breakthrough Initiatives, a large-scale science programme to search for extraterrestrial intelligence. We chatted to Markus Kasper, ESO exoplanet expert, to learn more.

    Q: Markus, how did you come to be involved in the Breakthrough Initiatives?

    A: The Breakthrough Initiatives are a suite of scientific and technological programmes dedicated to probing the questions of life in the Universe. In 2015, back before ESO was officially involved, I was invited to join the committee of one of these programmes: Breakthrough Watch (BTW). The objective of BTW is to look for ways to find habitable exoplanets within a five parsec (16 light-year) search radius from Earth.

    To me, this is the most interesting science goal in modern astronomy, because these planets will be sufficiently nearby for the Breakthrough Starshot probes to get there on a reasonable timescale. Breakthrough Starshot is another branch of the initiatives, which aims to design and build ultra-fast, light-driven nano-spacecraft to send to the Alpha Centauri system. This is the closest star system to Earth at just four light-years away, consisting of the binary stars Alpha Centauri A and B, plus Proxima Centauri. But we need to find habitable planets in this system first!

    Q: Why are the Breakthrough Initiatives happening now? Why is this the right moment?

    A: Recent years have brought a wealth of exciting exoplanet discoveries, and we now know that the presence of rocky planets in the habitable zone of a star is the rule rather than an exception. For example, ESO instruments have very recently discovered potentially habitable planets orbiting some of our nearest neighbours like Proxima Centauri and Ross 128. With the emerging class of extremely large telescopes currently under construction, the detection of biosignatures in the atmospheres of nearby exoplanets — gases like oxygen or methane that might indicate past or present life — will be within reach during the next decade, so now is the perfect time to find these exciting planets.

    3
    This artist’s impression shows a view of the surface of the planet Proxima b orbiting the red dwarf star Proxima Centauri, the closest star to the Solar System. The double star Alpha Centauri AB also appears in the image. Credit: ESO/M. Kornmesser

    Q: Tell us more about how Breakthrough Watch will achieve its goals.

    A: A big problem in exoplanet discovery is that stars are incredibly bright in comparison to their planets, and so habitable planets are hard to detect. But at mid-infrared wavelengths, between 10 and 20 microns, habitable planets become much brighter and are easier to find — between 10 and 12.5 microns, the Earth is actually the brightest planet in the Solar System.

    During the initial meetings of the BTW committee, we identified thermal imaging with 8-metre ground-based telescopes — such as ESO’s Very Large Telescope — as one of the best short-term opportunities to search for Earth-sized, rocky planets in the Alpha Centauri system. In 2016 ESO signed an agreement with Breakthrough Initiatives to follow through with this plan. Agreements for similar efforts with other large observatories (such as Gemini and Magellan) are being considered as well.

    ESO’s goal with NEAR (New Earths in the Alpha cen Region) is to improve the contrast and sensitivity of the existing Very Large Telescope instrument VISIR (VLT Imager and Spectrometer for mid-Infrared) at ESO’s Paranal Observatory in Chile. The proximity of Alpha Centauri means that we could detect of a habitable planet in just 100 hours of observing time on the VLT.

    4
    Every day, before the observations start, each telescope of the VLT undergoes a complete start-up during which each of its function is checked, like a plane before take off. Here, VISIR is visible at the Cassegrain focus of UT3. Credit: ESO

    Q: What technology is being developed to make these observations?

    A: There are three main areas of technological innovation in the NEAR project. Firstly, Adaptive Optics (AO) will be used to improve the point source sensitivity of VISIR. The AO will be implemented by ESO, building on the newly-available deformable secondary mirror at the VLT’s Unit Telescope 4 (UT4).

    ESO/VISIR

    Secondly, a team led by the University of Liège (Belgium), Uppsala University (Sweden) and Caltech (USA) will develop a novel vortex coronagraph to provide a very high imaging contrast at small angular separations. This is necessary because even when we look at a star system in the mid-infrared, the star itself is still millions of times brighter than the planets we want to detect, so we need a dedicated technique to reduce the star’s light. A coronagraph can achieve this.

    Finally, a module containing the wavefront sensor and a new internal chopping device for detector calibration will be built by our contractor Kampf Telescope Optics in Munich.

    6
    This image shows the closest stellar system to the Sun: the bright double star Alpha Centauri AB and its faint companion Proxima Centauri.
    Credit: ESO/B. Tafreshi (twanight.org)/Digitized Sky Survey 2 Acknowledgement: Davide De Martin/Mahdi Zamani

    7
    Glistening against the awesome backdrop of the night sky above ESO’s Paranal Observatory, four laser beams project out into the darkness from Unit Telescope 4 (UT4) of the VLT.
    Credit: ESO/F. Kamphues

    Q: What challenges do you expect to face?

    A: Generally, moving an instrument to a different telescope (in this case, we are moving VISIR from UT3 to UT4) is never a small task, especially for the operations staff at the observatory. An additional challenge is that we have to make NEAR work at its best with a fixed deadline and with sparse resources. The performance goals are very demanding and require one part in a million contrast at less than one arcsecond separation — which is a challenge similar to detecting a firefly sitting on a lighthouse lamp from a few hundred kilometres away! This has not yet been demonstrated in the thermal infrared.

    Q: How long will these first big developments take?

    A: The testing of the hardware in Europe is taking place now, during the first half of 2018. It will be implemented in VISIR at Paranal by end of 2018. The Alpha Centauri observing campaign is scheduled for mid-2019 and will last for about two weeks to collect the required 100 hours of observation time, once the system is delivering the expected performance.

    Q: What exactly is your role in the project?

    A: The work on NEAR is carried out by a small and highly motivated core team at ESO, in collaboration with engineers and scientists from various institutions and countries who are part of the ESO community, as well as industrial partners. My personal role, besides making the link to the Breakthrough Initiatives as a representative, is quite diverse. I mostly work on the design and analysis of the instrumental modifications, but I also develop the concepts for optimum observing and exploitation of the campaign data.

    Q: For you, what is the most exciting aspect of this endeavour?

    A: Besides the fascinating science goals, it is exciting to see how the Breakthrough Initiatives are managing to create momentum in the research field. By backing ideas and projects with a higher risk level than public funding agencies are ready to support, the Initiatives have motivated scientists to push the envelope and leap forward in their research. The Breakthrough Listen branch, for example, searches the sky for radio and laser signals emitted by intelligent beings over a volume in space that is orders of magnitudes larger than what has previously been observed.

    __________________________________________________
    By backing high-risk ideas and projects, the Initiatives have motivated scientists to push the envelope and leap forward in their research
    __________________________________________________

    Q: What hopes do you have for the outcomes of the Breakthrough Initiatives?

    A: I am quite optimistic that we’ll achieve our technical and sensitivity goals with NEAR. Of course, we do not know whether the planets we are looking for actually exist in the Alpha Centauri system. The fact that Alpha Centauri A and B are a relatively close binary may make it more difficult for planets to have formed and exist in the system. The chances are hard to quantify, but if we detected a habitable planet in the Alpha Centauri system it would have incredible impacts even beyond astronomical science — which makes it worth looking anyway.

    And identifying such planets isn’t even the biggest challenge on the cards. Once we know what’s out there, Breakthrough Starshot will aim for in-situ exploration of these systems using microsatellites, which is a whole new technological ball game!

    See the full article here .

    Please help promote STEM in your local schools.
    STEM Icon

    Stem Education Coalition
    Visit ESO in Social Media-

    Facebook

    Twitter

    YouTube

    ESO Bloc Icon

    ESO is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive ground-based astronomical observatory by far. It is supported by 16 countries: Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Poland, Portugal, Spain, Sweden, Switzerland and the United Kingdom, along with the host state of Chile. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope, the world’s most advanced visible-light astronomical observatory and two survey telescopes. VISTA works in the infrared and is the world’s largest survey telescope and the VLT Survey Telescope is the largest telescope designed to exclusively survey the skies in visible light. ESO is a major partner in ALMA, the largest astronomical project in existence. And on Cerro Armazones, close to Paranal, ESO is building the 39-metre European Extremely Large Telescope, the E-ELT, which will become “the world’s biggest eye on the sky”.

    ESO LaSilla
    ESO/Cerro LaSilla 600 km north of Santiago de Chile at an altitude of 2400 metres.

    ESO VLT
    VLT at Cerro Paranal, with an elevation of 2,635 metres (8,645 ft) above sea level.

    ESO Vista Telescope
    ESO/Vista Telescope at Cerro Paranal, with an elevation of 2,635 metres (8,645 ft) above sea level.

    ESO NTT
    ESO/NTT at Cerro LaSilla 600 km north of Santiago de Chile at an altitude of 2400 metres.

    ESO VLT Survey telescope
    VLT Survey Telescope at Cerro Paranal with an elevation of 2,635 metres (8,645 ft) above sea level.

    ALMA Array
    ALMA on the Chajnantor plateau at 5,000 metres.

    ESO E-ELT
    ESO/E-ELT to be built at Cerro Armazones at 3,060 m.

    ESO APEX
    APEX Atacama Pathfinder 5,100 meters above sea level, at the Llano de Chajnantor Observatory in the Atacama desert.

    Leiden MASCARA instrument, La Silla, located in the southern Atacama Desert 600 kilometres (370 mi) north of Santiago de Chile at an altitude of 2,400 metres (7,900 ft)

    Leiden MASCARA cabinet at ESO Cerro la Silla located in the southern Atacama Desert 600 kilometres (370 mi) north of Santiago de Chile at an altitude of 2,400 metres (7,900 ft)

    ESO Next Generation Transit Survey at Cerro Paranel, 2,635 metres (8,645 ft) above sea level

    SPECULOOS four 1m-diameter robotic telescopes 2016 in the ESO Paranal Observatory, 2,635 metres (8,645 ft) above sea level

    ESO TAROT telescope at Paranal, 2,635 metres (8,645 ft) above sea level

    ESO ExTrA telescopes at Cerro LaSilla at an altitude of 2400 metres

     
  • richardmitnick 1:38 pm on March 16, 2018 Permalink | Reply
    Tags: , ALMA - Breathless Science, , , , , ESOblog, ,   

    From ESOblog: “Breathless Science” 

    ESO 50 Large

    ESOblog

    16 March 2018

    1
    On the Ground

    At a soaring altitude of 5100 metres above sea level, the ALMA Observatory is one of the world’s most extreme work environments. Athletes and hikers who climb this high usually move up slowly in altitude to adjust to the lower oxygen levels. But at ALMA, workers go from the Operations Support Facility (OSF) at 2900 metres up to the array of antennas at 5100 metres in less than an hour — and they go up and down daily. We spoke to Ivan Lopez, ALMA’s Safety Manager, to find out how to minimise the negative effects of high altitude on the health of workers.

    2
    Iván López

    Q: Tell us about your staff — what kinds of people work at ALMA and the OSF?

    A: We have on average 250 people at our observatory. From those, approximately 50 are exposed to intermittent hypoxia, which is a medical condition where the body does not get sufficient oxygen. We need all types of workers and their skills: from cleaning staff, to electrical and mechanical technicians, to a range of civil engineers, to our scientists. The astronomers who end up using ALMA data seldom need to work at the high site.

    Q: What are the conditions like for your staff?

    A: Our facilities in the Atacama Desert are essentially like small towns located in remote places, where the access to entertainment, leisure, medical care, and contact with loved ones is limited. This takes its toll on the sociological, psychological and personal development of our teams. But the environment is one of our biggest challenges. The ALMA site of is one of the driest on Earth, with very extreme weather and fast changes between conditions — we can have all four seasons in one day!

    Perhaps most importantly, we are confronted with rapid altitude changes that physiologically affect our workers’ bodies. Low oxygen levels make our work unsafe and more difficult. Since we must travel from 2900 to 5100 metres above sea level in just 45 minutes, we are exposed to hypoxia.

    3
    This panoramic view of the Chajnantor Plateau shows ALMA bathed in a spectacular sunset. It captures the feeling of solitude experienced at the ALMA site and the otherworldly appearance of the terrain.
    Credit: Y. Beletsky/ESO.

    Q: What is hypoxia and what effects does it have?

    A: Hypoxia is a deficiency in the amount of oxygen that reaches the body’s tissues. The severity of its effects depends on the length of exposure and the person’s physiology. We’ve been working with the University of Zurich in Switzerland, the University of Calgary in Canada, and the Universidad Católica del Norte in Chile to study the effects of hypoxia, as well as possible solutions for how to reduce these effects in our workers. It’s a great win-win for all of us. The medical researchers enjoy working with us — ALMA is like a natural laboratory for these studies due to its high altitude — and we, in turn, learn new information that we can use to take precautionary measures for our staff.

    4
    ALMA Transporter Operator Patricio Saavedra working with oxygen at 5000 metres. Credit: ESO/Max Alexander.

    In the latest round of studies in 2016, researchers examined our workers who volunteered over six weeks, examining their cognitive skills, sleep quality, breathing patterns, blood flow to the brain, and changes in blood flow between the heart and lungs. The studies are currently being reviewed and will be published this year. Among the many things we learned, we found out that hypoxia influences a worker’s quality of sleep, attention span, and short-term memory. This poses a real danger, as it negatively impacts the quality, productivity and safety of our workers and equipment, since many of our staff work on tasks that require a high level of concentration. This means that accident probability goes up since people are less alert.

    Q: Facing these risks, how do you ensure that staff working at ALMA and the OSF are safe?

    A: The results of these ongoing studies have made us change our daily programme, activities, and procedures to create a safer working environment. We’re currently making changes to our approach to safety and health, which has been used as a model across our facilities and Chile. We also carry out our High Altitude Medical Evaluation every year, which means that each worker gets a green light from a doctor more often than required by the Chilean authorities.

    _______________________________________________
    Among the many things we have changed, we have made the use of portable medical oxygen mandatory.
    _______________________________________________

    Among the many things we have changed, we have made the use of portable medical oxygen mandatory for all drivers from the 3000 metres above sea level and up, and for all workers on the Chajnantor Plateau where the antennas are located. The O2 tanks have evolved from big, bulky, heavy cylinders to smaller lightweight tanks made of carbon fibre. At the beginning, they are uncomfortable for the worker to use, but they get used to it — we’ve even designed backpacks to carry the O2 tank everywhere. Since we use liquified O2 that is very dry, we monitor our workers and provide nasal sprays to moisturise their airways.

    4
    The Array Operations Site (AOS) is the basecamp for the routine operations of the ALMA facility and the second highest building in the world. The AOS Technical Building houses the ALMA correlator — the highest-altitude supercomputer in the world. The air is so thin that the correlator’s fan system requires twice the usual airflow to keep it cool. Here Enrique Garcia, a correlator technician, examines the supercomputer system while breathing oxygen from a tank in his backpack. Credit: ESO/Max Alexander.

    The AOS (Array Operations Site) technical building on the Chajnantor plateau is also now permanently oxygenated (we have a liquid oxygen plant installed). It is also recommended that drivers going up and down our road have a copilot; that staff should work in teams of at least two; that supervisors should plan their work activities to follow exact procedures, with workers following bullet lists of small tasks; and that workers should limit the number of working hours at high altitude, optimising their shifts.

    We limit the time that all our workers, including contractors, spend at 5100 metres. Each of our staff work on a roster — eight days working at the site, and six days off work back at sea level. The day that they arrive, they are not allowed to go up to the high site. The second day of their shift, they are allowed to go up for just four hours; the third day for six hours; and from the fourth to the eighth day, a maximum of eight hours. No one is allowed to sleep at the high site.

    6
    This is no ordinary truck — it is an ALMA transporter, called Lore. At 20 metres long and 10 metres wide, this is one of a pair of custom-designed vehicles used to transport the 66 antennas that make up ALMA. Credit: Enrico Sacchetti/ESO.

    We have also increased our medical staff to have one registered nurse, stationed at the OSF, plus two paramedics on shift at all times. The paramedics go out on-site to perform field checks and constantly monitor the workers. A medical doctor visits twice a week to attend to all the needs of our workers. We also continuously train our staff in the latest developments on how to handle hypoxia and develop new strategies such a special diet and exercise program.

    Q: Why does a special diet need to be developed?

    A: High altitude can make it more difficult for the body to digest food. Ideally, our workers should have small snacks at different times of the day, such as dried fruits, almonds, nuts, fresh juice, power bars — mostly fast-release energy foods. We need to avoid heavy meals because they will take longer to digest at such heights. For example, right now we have removed soda beverages, broccoli, onions, cauliflower, turkey, beans and legumes from the meals. Managing our workers’ diets is actually one of the biggest challenges we have since the local workers are used to having big meals — something that has been rooted in their culture for generations.

    Q: Have any workers experienced severe altitude sickness, or has there been an altitude-related accident?

    A: Our programme has been very effective, so we have not had a serious or fatal incident related to hypoxia. But this does not mean that we have not had emergencies! We’ve had three serious emergencies where workers needed to be carried down to the nearby city of Calama. Around 15 visitors have also experienced minor hypoxia-related symptoms that needed attention.

    Luckily, our polyclinic staff have over 10 years of experience working at high altitudes and are regularly trained to deal with emergency situations. Our polyclinic is also equipped with three ambulances, two portable hyperbaric chambers, a cardiac arrest device, an emergency crash cart, and we have a contract with Telemedicina for the remote monitoring of heart illnesses. So we are very prepared to deal with emergencies.

    Q: What are the long-term effects of working at high altitude?

    A: The scientific literature has found that there are some long-term effects to hypoxia, mostly related to untreated issues or precautions have not been taken; but the studies performed so far have mostly been related to athletes or people who have suffered hypoxia-related accidents. There is very little available information on workers like ours in the long term. That is the reason why we are taking extreme care, continually monitoring our workers and partnering with universities to perform further studies.

    Q: Tell us about your role as Safety Manager.

    A: My office handles Safety, Health, Environment and Security at the ALMA Observatory, which includes managing the well-being of our people, the assessment of equipment, risk prevention, and our fire brigade team. We are also in charge of taking care of our environment by imposing regulations and resolutions based on environmental impact studies. We manage and develop ALMA’s health program and are also in charge of the management of the security contract.

    7
    Inside the Operations Support Facility (OSF), over 2000 metres below Chajnantor Plateau, ALMA test scientists go through the process of calibrating and testing the accuracy of an antenna. Credit: ESO/M. Alexander.

    Q: Can the extreme conditions affect the actual machinery of ALMA?

    A: Yes, and our engineers are constantly reviewing and adapting changes to cope with this. Antenna parts are being constantly modified and designed so we can meet with the requirement of our scientific clients, and many parts that were supposed to last a certain amount of years are actually lasting half of that time. The amount of time predicted for workers to carry out tasks has also been affected.

    Bear in mind that we are currently one of the few organisations in the world that has a wide array of equipment operating at these altitudes in such extreme conditions. Most information about how to function at these heights has not yet been shared by companies, mostly in the mining industry, who face similar challenges. So we are learning as we go. Our team has people with experience gained at the observatories in Hawaii and at APEX so we try to use their knowledge as a basis for many processes.

    Q: Has ESO shared its findings with the wider community?

    A: Yes, we have. There is not yet an international regulation for working at high altitude, so the data collected at ALMA is groundbreaking in the field and serves as a reference for ongoing medical studies. We are proud to say that the Chilean government has used our results to develop and change the current Chilean regulations on hypoxia, and we have participated in labour and health conferences to explain our approach to hypoxia. We are also an active part of the Lake Louise Hypoxia conference that is held every two years, where worldwide researchers show and explain their findings. One Peruvian company is using our health programme as a model for their own.

    Other observatories also face the same problems as they build their telescopes at high altitudes to escape the effects of atmospheric distortion. We have formed a group of safety managers from different observatories who meet periodically to share experiences and findings.

    See the full article here .

    Please help promote STEM in your local schools.
    STEM Icon

    Stem Education Coalition
    Visit ESO in Social Media-

    Facebook

    Twitter

    YouTube

    ESO Bloc Icon

    ESO is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive ground-based astronomical observatory by far. It is supported by 16 countries: Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Poland, Portugal, Spain, Sweden, Switzerland and the United Kingdom, along with the host state of Chile. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope, the world’s most advanced visible-light astronomical observatory and two survey telescopes. VISTA works in the infrared and is the world’s largest survey telescope and the VLT Survey Telescope is the largest telescope designed to exclusively survey the skies in visible light. ESO is a major partner in ALMA, the largest astronomical project in existence. And on Cerro Armazones, close to Paranal, ESO is building the 39-metre European Extremely Large Telescope, the E-ELT, which will become “the world’s biggest eye on the sky”.

    ESO LaSilla
    ESO/Cerro LaSilla 600 km north of Santiago de Chile at an altitude of 2400 metres.

    ESO VLT
    VLT at Cerro Paranal, with an elevation of 2,635 metres (8,645 ft) above sea level.

    ESO Vista Telescope
    ESO/Vista Telescope at Cerro Paranal, with an elevation of 2,635 metres (8,645 ft) above sea level.

    ESO NTT
    ESO/NTT at Cerro LaSilla 600 km north of Santiago de Chile at an altitude of 2400 metres.

    ESO VLT Survey telescope
    VLT Survey Telescope at Cerro Paranal with an elevation of 2,635 metres (8,645 ft) above sea level.

    ALMA Array
    ALMA on the Chajnantor plateau at 5,000 metres.

    ESO E-ELT
    ESO/E-ELT to be built at Cerro Armazones at 3,060 m.

    ESO APEX
    APEX Atacama Pathfinder 5,100 meters above sea level, at the Llano de Chajnantor Observatory in the Atacama desert.

    Leiden MASCARA instrument, La Silla, located in the southern Atacama Desert 600 kilometres (370 mi) north of Santiago de Chile at an altitude of 2,400 metres (7,900 ft)

    Leiden MASCARA cabinet at ESO Cerro la Silla located in the southern Atacama Desert 600 kilometres (370 mi) north of Santiago de Chile at an altitude of 2,400 metres (7,900 ft)

    ESO Next Generation Transit Survey at Cerro Paranel, 2,635 metres (8,645 ft) above sea level

    SPECULOOS four 1m-diameter robotic telescopes 2016 in the ESO Paranal Observatory, 2,635 metres (8,645 ft) above sea level

    ESO TAROT telescope at Paranal, 2,635 metres (8,645 ft) above sea level

    ESO ExTrA telescopes at Cerro LaSilla at an altitude of 2400 metres

     
  • richardmitnick 12:56 pm on March 11, 2018 Permalink | Reply
    Tags: , , , , ESOblog, Scanning a galaxy halo   

    From ESOblog: “Scanning a galaxy halo” 

    ESO 50 Large

    ESOblog

    7

    Using MUSE and gravitational lensing to solve the mysteries of galaxy halos.

    ESO MUSE on the VLT

    ESO Adaptive Optics with MUSE

    Every galaxy is surrounded by a mysterious halo that scientists currently know little about. A team of astronomers has recently used a new technique to map the structure of a distant galaxy halo that is located in between a giant background galaxy and a huge foreground gravitational lens — like a galaxy halo sandwich. We spoke to lead scientist Sebastian Lopez from the Universidad de Chile to find out more about the surprising results.

    Q. Firstly, what are galaxy halos and why is it interesting to study them?

    A: A galaxy halo is the “invisible” part of a galaxy which extends out well beyond the visible starlight. If the stars of the galaxy are the “main part”, then the gaseous halo of some galaxies can extend out to ten times the size of this main part — measuring up to millions of light-years across. Each galaxy has this invisible halo that is really intriguing but very tricky to study. We believe these halos consist partly of normal matter in gaseous form — mostly hydrogen and helium — but also of dark matter, which is something more mysterious that we don’t yet understand.

    Galaxy halos are interesting to study for two reasons. Firstly because over time they collapse to eventually form star-forming galaxies, just like the one that we live in, and secondly because they remain enigmas. We want to crack them open and find out how they work, to learn more about the processes of galaxy formation and evolution!

    1
    This artist’s impression shows the Milky Way galaxy. The blue halo of material surrounding the galaxy indicates the expected distribution of the mysterious dark matter. Credit: ESO/L. Calçada

    A: In 1920 there was a huge discussion — fittingly called The Great Debate — between two astronomers, Shapley and Curtis, about whether some observed distant nebulae were truly clouds of dust and gas within the Milky Way, or whether they were actually independent galaxies much further away. The latter option, supported by Curtis, turned out to be correct. Astronomers suspected that these independent galaxies would each have a gaseous halo. However, the first real detection of a galaxy halo outside our galaxy wasn’t until the late 1960s, when John Bahcall and Edwin Salpeter looked at distant quasars and found mysterious red-shifted absorption lines, which suggested that some of the light had been absorbed by gases in an intervening galaxy halo.

    Q. Did astronomers continue to use quasars to study galaxy halos?

    A: Yes, for many years! Quasars are a special kind of extragalactic object that can be found at the centres of active galaxies. Their energy is produced by material falling into a supermassive black hole. Because they can shine as brightly as 10 000 normal galaxies, we can observe quasars that are extremely distant (the most distant known quasar is so far away that it has taken almost the entire lifetime of the Universe for its light to reach us). Light from distant quasars passes through intervening galaxies and therefore travels through galactic halos on its journey to the Earth. Every time this happens, the halos imprint their signature — a kind of fingerprint — on the quasar light in the form of absorption lines in the quasar spectrum. Analysing the properties of these lines gives us information about the gaseous halo of intervening galaxies, which would otherwise remain invisible.

    2
    This artist’s impression shows that when light passes through intervening galaxies, certain wavelengths are absorbed, leaving a signature in the absorption spectrum. Credit: ESO/L. Calçada

    Q. That brings us to your research — tell us about your new technique to study galaxy halos.

    A: Over the past decades, our ability to capture the spectra of quasars has improved enormously. Astronomers can now build a much better picture of the gas structure around galaxies. However, a quasar is so distant that it looks as small as a star, so this technique is a bit like probing one narrow pencil beam through a galaxy halo. That’s where our technique comes in. Instead of looking at a quasar through a galaxy halo, we decided to look at a much larger background object, so that we could investigate the whole structure of a galaxy halo in more detail.

    We made use of an effect called gravitational lensing. Massive objects are capable of curving spacetime; when light passes close to those curved regions of spacetime, it follows the curvature so that the light rays appear to be bent and magnified. This is important because in our study, we could observe a distant galaxy more easily since it was being magnified (and distorted) by a foreground galaxy cluster. The result is a very extended arc on the sky.

    This project therefore combined expertise from two different areas of astronomy — in the circumgalactic medium and in the field of galaxy clusters.

    Q. Talk us through exactly what you studied.

    A: Some of our team members had previously found a distant, giant, and very bright gravitational arc, catchily known as RCS2 032727-132623. This arc is the image of a background galaxy, gravitationally lensed by an intervening galaxy cluster. In between this background galaxy and us is another little galaxy system, which we named G1. When light from the arc passes through the halo of G1, G1’s absorption signature is imprinted onto its spectrum. Now, this is the cool part: because the giant arc is so extended across the sky, its light travels through a large area of G1 (unlike a quasar’s narrow beam of light). By studying this arc with the MUSE instrument on ESO’s Very Large Telescope, we could pick out lots of individual spectra that showed “fingerprints” from many different places in the halo of G1.

    For each spectrum that we obtained, we looked at the signatures of magnesium in the halo of G1, which told us about the overall distribution of metals in the halo.

    3
    Light from the background galaxy (“source plane”) is deflected and magnified by an intervening galaxy cluster (“lens plane”), to form the bright giant arc that is seen in the projected image (the right-most panel). Credit: Carlos Polanco

    Q. Tell us about your results. Did you find out anything interesting?

    A: This is the first time anybody has studied many different positions within a distant galaxy halo to find out about its structure. Since this was the first time, the data reduction and further analysis were slower than usual because we had to make several tests — but it was still quite exciting!

    We found that the amount of magnesium in G1’s halo decreases with distance from the main part of the galaxy. We knew about this behaviour from studies using quasars, but our experiment allowed us to check it for the first time in this single halo. We also confirmed that the gas in the halo of G1 is clumpy — meaning there is an uneven distribution of heavier elements.

    Yet, heavier elements like metals are produced in galaxies themselves, not in halos. So we began to investigate how they could have travelled outwards. We asked ourselves: is the velocity of the gas in the halo the same as the velocity of G1 itself? No. What about compared to possible outflowing gas? Also no. Instead, we found that the velocity of gas in the halo is “quiet” — the gas seems to be locked to a huge structure that doesn’t seem to move much with respect to the galaxy system.

    4
    The gravitational arc of the background galaxy stretches across the field of view, its light shining through G1. By taking spectra from different positions along the arc, astronomers have found clear evidence for magnesium absorption. The more absorption of light by magnesium, the lighter the pixel. Credit: Lopez et al., Nature 2018

    Q. Was this surprising?

    A: We were definitely surprised by our results because we found metal-enriched gas far from G1 and yet the lack of movement in the system gives no explanation of how the gas got so far away — we expected to see some signs of outflowing material, but we didn’t. Also, it seems that metal-enriched gas is present only in certain directions from G1, which will be very relevant to the way people design absorption surveys using quasars as background sources.

    Our new approach to probe distant galaxy halos with arcs won’t replace using quasars as background sources — because distant quasars are way more numerous than gravitational arcs, blind surveys of quasar absorption lines remain particularly important in the field. This said, our results on the directionally-dependent geometry of this particular halo will have to be taken into account when interpreting why not all quasar sightlines encounter absorbing material, despite passing close to a known galaxy.

    Q: Why is MUSE the only instrument that can undertake such studies?

    A: The MUSE instrument, which is mounted on one of the VLT’s Unit Telescopes, is an integral-field spectrograph. This means that it is capable of taking thousands of spectra at the same time for each pixel in a given area on the sky — resulting in a 3D “datacube”. In particular, MUSE can take some 100 000 spectra in one shot of a 1×1 arcmin field of view (an area just a bit bigger than the size of Jupiter as it appears in Earth’s sky), covering what we call the visible wavelength range.

    Now, why is this important to our study? Our source, the gravitational arc, is as extended over about 1 arcminute — so it fits nicely in one MUSE field of view! We also needed spectra of every position on the arc to probe the intervening absorption, and of every galaxy in the field to discover the absorbing galaxy, and MUSE was the only instrument in the world able to provide these kinds of data. Our final datacube can also be seen as a “stack” of lots of images of the arc, taken with different filters at different wavelengths. Because wavelength is related to radial velocity via the Doppler effect, in practice we sliced the absorbing halo by velocity, ending up with a tomographic view of it. With its superb capabilities, MUSE allowed us to do this in quite a straightforward fashion. In passing, I would like to thank ESO staff for obtaining these data for us so efficiently. No doubt MUSE is currently one of the most requested instruments on ESO telescopes!

    5
    Artist’s rendering of the Extremely Large Telescope, which may be used to probe gravitational arcs and galaxy halos in the future. Credit: ESO/L. Calçada

    Q. What are the next steps in this area of astronomy? What are you excited to see?

    A: Well, we want to repeat this experiment using more arcs! Our team has already found some suitable candidates. We expect these arcs to have different configurations and also to reveal different kinds of absorption systems. Bright and extended arcs are rare objects today, but future wide-field surveys will discover hundreds of them. Some of those new arcs will be perhaps too faint for MUSE but are certainly a good case for an integral field unit on the future Extremely Large Telescope. Besides opening a new observational dimension in studies of galaxy halos, we expect these results to tell us more about galaxy evolution.

    See the full article here .

    Please help promote STEM in your local schools.
    STEM Icon

    Stem Education Coalition
    Visit ESO in Social Media-

    Facebook

    Twitter

    YouTube

    ESO Bloc Icon

    ESO is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive ground-based astronomical observatory by far. It is supported by 16 countries: Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Poland, Portugal, Spain, Sweden, Switzerland and the United Kingdom, along with the host state of Chile. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope, the world’s most advanced visible-light astronomical observatory and two survey telescopes. VISTA works in the infrared and is the world’s largest survey telescope and the VLT Survey Telescope is the largest telescope designed to exclusively survey the skies in visible light. ESO is a major partner in ALMA, the largest astronomical project in existence. And on Cerro Armazones, close to Paranal, ESO is building the 39-metre European Extremely Large Telescope, the E-ELT, which will become “the world’s biggest eye on the sky”.

    ESO LaSilla
    ESO/Cerro LaSilla 600 km north of Santiago de Chile at an altitude of 2400 metres.

    ESO VLT
    VLT at Cerro Paranal, with an elevation of 2,635 metres (8,645 ft) above sea level.

    ESO Vista Telescope
    ESO/Vista Telescope at Cerro Paranal, with an elevation of 2,635 metres (8,645 ft) above sea level.

    ESO NTT
    ESO/NTT at Cerro LaSilla 600 km north of Santiago de Chile at an altitude of 2400 metres.

    ESO VLT Survey telescope
    VLT Survey Telescope at Cerro Paranal with an elevation of 2,635 metres (8,645 ft) above sea level.

    ALMA Array
    ALMA on the Chajnantor plateau at 5,000 metres.

    ESO E-ELT
    ESO/E-ELT to be built at Cerro Armazones at 3,060 m.

    ESO APEX
    APEX Atacama Pathfinder 5,100 meters above sea level, at the Llano de Chajnantor Observatory in the Atacama desert.

    Leiden MASCARA instrument, La Silla, located in the southern Atacama Desert 600 kilometres (370 mi) north of Santiago de Chile at an altitude of 2,400 metres (7,900 ft)

    Leiden MASCARA cabinet at ESO Cerro la Silla located in the southern Atacama Desert 600 kilometres (370 mi) north of Santiago de Chile at an altitude of 2,400 metres (7,900 ft)

    ESO Next Generation Transit Survey at Cerro Paranel, 2,635 metres (8,645 ft) above sea level

    SPECULOOS four 1m-diameter robotic telescopes 2016 in the ESO Paranal Observatory, 2,635 metres (8,645 ft) above sea level

    ESO TAROT telescope at Paranal, 2,635 metres (8,645 ft) above sea level

    ESO ExTrA telescopes at Cerro LaSilla at an altitude of 2400 metres

     
  • richardmitnick 1:58 pm on February 23, 2018 Permalink | Reply
    Tags: , , , , ESO’s Training Programmes: Investing in the Future of Astronomy, ESOblog   

    From ESOblog: “ESO’s Training Programmes: Investing in the Future of Astronomy” 

    ESO 50 Large

    ESOblog

    23 February 2018

    1

    With most of 2018 ahead of us, many people choose to condense their hopes, aims and regrets into firm statements of resolution. In this year’s first instalment of Letters from the DG, Xavier Barcons uses this period of reflection to talk about ESO’s training programmes set up to achieve the values and aims that underpin our work here, and to help foster collaboration in astronomy — one of ESO’s missions.

    Greetings and welcome back to the ESOBlog!

    Besides building and operating world-class astronomical facilities, ESO’s mission also includes fostering cooperation in astronomy, across our Member States and beyond. Attracting early-career scientists and engineers interested in astronomy and training them in the unique international environment that ESO represents is an incredibly successful recipe to promote cooperation, particularly when these talented people continue their professional careers elsewhere. Many internationally-renowned astronomical institutions around the world are now home to ESO’s former students, fellows and trainees, and in some cases, our alumni have leading responsibilities.

    Lifelong training

    Astronomy is constantly evolving, and ESO strives to ensure that not only astronomers, but also engineers, support staff and interested members of the public are kept at the forefront of this exciting and dynamic field of research.

    For this reason, we maintain an arsenal of fellowships, studentships, internships and training programmes for a diverse range of people. ESO’s multinational environment means we are in a unique position to provide varied and complex development and support, sustained by a diverse set of people, and this cannot start too young.


    Find out about the ESO Studentship Programme and hear students share stories of their time at ESO.
    Credit: ESO. Music: STAN DART (www.stan-dart.com)

    3
    A group of PhD students at the IMPRS Workshop 2017
    Credit: IMPRS on Astrophysics at the Ludwig-Maximilians Universität München

    Many of our in-house programmes focus on nurturing young astronomers as they progress from their studies into research and academia. The ever-popular Studentship Programme has been running since 1990, giving PhD students the opportunity to spend up to two years of their PhD programme at ESO to get hands-on research experience. So far, more than 200 students have participated in the programme either in Germany or Chile, remaining under the formal supervision of their home university, but with the benefit of co-supervision by an ESO staff astronomer and the mentorship of an ESO Fellow. Leading scientists, instrument experts and other professionals are all within easy reach, providing students with opportunities and skills invaluable to their future careers.

    Located at the renowned Garching Forschungszentrum campus near Munich in Germany, ESO is in a prime position to offer unique opportunities through partnerships with some of our incredible neighbouring institutions. Together, ESO, the MPE, MPA and USM have joined forces to coordinate a PhD programme: the IMPRS (International Max-Planck Research School on Astrophysics). Every year ESO hosts two to four PhD students within the IMPRS programme at Garching.

    But astronomers are not the only ones who benefit from lifelong training — astronomical research is ultimately funded by society and it appeals innately to people of all ages and cultures. ESO currently offers a range of unique learning experiences for school students. This includes visits to ESO during our annual Open House Days and participation in Germany’s “Girls’ Day”, when ESO opens its doors to female school students with tours of the main laboratories, as well as hands-on workshops in astronomy and engineering.

    ESO is also thrilled to be opening the new ESO Supernova Planetarium & Visitor Centre in April 2018, which will be a beacon of science education and outreach here at ESO Headquarters in Garching. School students and the general public will visit to learn about the Universe, and teachers will be offered training to keep up with advances in astronomy.

    4
    The participants of Girls’ Day 2014 at ESO Headquarters in Garching, Germany
    Credit: ESO

    High school students can also have life-changing experiences at the summer and winter astronomy camps, of which ESO is a proud partner. These camps include night-time observations with professional astronomers, lectures and social activities, and can be a formative part of young people’s academic and personal lives.

    5
    Students participating in the Summer AstroCamp 2016.
    Credit: ESO/C. Martins

    In 2016, the first ESO/NEON Observing School was held at the La Silla Observatory for postdoctoral researchers, PhD students, and advanced master’s students. This school provided hands-on real-life experience in the full astronomical research cycle, from proposal preparation to data reduction, as well as career advice for future astronomers. Thanks to the success of the first edition, a second edition will take place in February–March 2018.

    Supporting the Leaders of Tomorrow

    ESO Fellowships are another incredibly rewarding part of ESO’s training arsenal. Several postdoctoral fellowships are awarded to scientists with a PhD each year in Germany and in Chile. ESO Fellows can conduct independent research in a supportive and highly-motivating world-class scientific environment. The years spent at ESO enrich Fellows with invaluable practical experience in supporting instrumentation, science data archive developments, public outreach activities, or science operations at ESO’s observatories in Chile. Previous Fellows have found these duties to be much more rewarding and helpful in their career than anticipated.

    In Germany, Fellows spend up to 25% of their time on such functional activities during their three-year fellowship; in Chile they spend 50%. For this reason, Fellows in Chile have a fourth year to work purely on their own research, which can be spent in any institute in Chile or in an ESO Member State.

    The fellowship programme has recently been expanded to other areas of expertise at ESO; in 2018 we are excited to kickstart the ESO Engineering and Technology Research Fellowship. This programme offers early-career researchers with a PhD in an engineering-related discipline the opportunity to take part in ESO projects.

    Some of the most encouraging feedback from young ESO Fellows has been the sense of community, friendship and collaboration they felt while working at ESO. The wide variety of people encountered at ESO makes it a great place to forge connections and develop key skills for the future. Many former ESO Fellows are now in leading positions at top astronomical research institutions around the world. In my first six months at ESO, I have seen a fabulous diaspora of our former early-career professionals coming back to ESO for short visits, maintaining valuable links with colleagues at their alma mater. To learn more about our impressive range of Fellows, past and present, I recommend this brochure.

    Encouraging Collaboration and Exchange

    A focus on community and international collaboration is at the heart of ESO’s ethical framework. Our goal is to foster strong and enjoyable relationships between everybody who passes through our doors, and we understand that no astronomer is an island. A scientific or technical career in astronomy involves teamwork, supervising other people, writing job and grant applications, collaborations between different countries and cultures, as well as some sleepless nights, stressful deadlines and great emotional investment. Diversity is a highly treasured asset at ESO, where people from more than 40 countries share a workplace and a great enthusiasm for their field. The fact that no one at ESO is a clone of any other makes our work especially enjoyable and productive.

    6
    Three Telescope and Instrument Operators joining forces to set up the complex system of the VLTI for an interferometric observation.
    Credit: ESO/H.H.Heyer

    Astronomy, like many other fields, requires a great deal of written and verbal communication. ESO has links with organisations such as the renowned Astronomy and Astrophysics journal, which is a partner in training schools for writing scientific papers. Specific to science communication, over the years ESO has also offered 3–6 month internships in graphic design and science communication to more than a hundred young people from ESO Member States and beyond.

    Astronomy is a fluid and dynamic field, where people move between organisations and learn new skills along the way. ESO trains people knowing they will at some point move to new pastures, and we benefit from people joining us with fresh perspectives and ideas. Ultimately, ESO aims to nurture people who will become ambassadors when they leave, promoting not just the work that we do but the values we hold dear.

    See the full article here .

    Please help promote STEM in your local schools.
    STEM Icon

    Stem Education Coalition
    Visit ESO in Social Media-

    Facebook

    Twitter

    YouTube

    ESO Bloc Icon

    ESO is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive ground-based astronomical observatory by far. It is supported by 16 countries: Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Poland, Portugal, Spain, Sweden, Switzerland and the United Kingdom, along with the host state of Chile. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope, the world’s most advanced visible-light astronomical observatory and two survey telescopes. VISTA works in the infrared and is the world’s largest survey telescope and the VLT Survey Telescope is the largest telescope designed to exclusively survey the skies in visible light. ESO is a major partner in ALMA, the largest astronomical project in existence. And on Cerro Armazones, close to Paranal, ESO is building the 39-metre European Extremely Large Telescope, the E-ELT, which will become “the world’s biggest eye on the sky”.

    ESO LaSilla
    ESO/Cerro LaSilla 600 km north of Santiago de Chile at an altitude of 2400 metres.

    ESO VLT
    VLT at Cerro Paranal, with an elevation of 2,635 metres (8,645 ft) above sea level.

    ESO Vista Telescope
    ESO/Vista Telescope at Cerro Paranal, with an elevation of 2,635 metres (8,645 ft) above sea level.

    ESO NTT
    ESO/NTT at Cerro LaSilla 600 km north of Santiago de Chile at an altitude of 2400 metres.

    ESO VLT Survey telescope
    VLT Survey Telescope at Cerro Paranal with an elevation of 2,635 metres (8,645 ft) above sea level.

    ALMA Array
    ALMA on the Chajnantor plateau at 5,000 metres.

    ESO E-ELT
    ESO/E-ELT to be built at Cerro Armazones at 3,060 m.

    ESO APEX
    APEX Atacama Pathfinder 5,100 meters above sea level, at the Llano de Chajnantor Observatory in the Atacama desert.

    Leiden MASCARA instrument, La Silla, located in the southern Atacama Desert 600 kilometres (370 mi) north of Santiago de Chile at an altitude of 2,400 metres (7,900 ft)

    Leiden MASCARA cabinet at ESO Cerro la Silla located in the southern Atacama Desert 600 kilometres (370 mi) north of Santiago de Chile at an altitude of 2,400 metres (7,900 ft)

    ESO Next Generation Transit Survey at Cerro Paranel, 2,635 metres (8,645 ft) above sea level

    SPECULOOS four 1m-diameter robotic telescopes 2016 in the ESO Paranal Observatory, 2,635 metres (8,645 ft) above sea level

    ESO TAROT telescope at Paranal, 2,635 metres (8,645 ft) above sea level

    ESO ExTrA telescopes at Cerro LaSilla at an altitude of 2400 metres

     
  • richardmitnick 1:30 pm on February 16, 2018 Permalink | Reply
    Tags: , , , , , ESOblog   

    From ESOblog: “How to Install a Planetarium A conversation with engineer Max Rößner about his work on the ESO Supernova” 

    ESO 50 Large

    ESOblog

    2

    Part of ESO Headquarters in Garching, Germany, is currently in a frenzy of activity as we prepare to open the ESO Supernova Planetarium & Visitor Centre in April 2018. This cutting-edge free astronomy centre is equipped with a 14-metre planetarium dome and an amazing exhibition that takes visitors on a journey to the stars. It’s a lot of work to install a planetarium system from scratch, but to engineer Max Rößner, the ESO Supernova is like a giant playground.

    ESO Supernova Planetarium, Garching Germany

    Q: What’s your role at the ESO Supernova Planetarium & Visitor Centre?

    A: I’d say that I am the Systems Engineer for the ESO Supernova planetarium. I concentrate on the technical implementation of the planetarium, integrating the projection and multimedia systems. Sometimes I also work on the content — such as the shows and night sky tours that will be played on the dome. There is quite a lot of pressure, as at the moment I am the only person who entirely understands the planetarium system, so in a way the project depends on me.

    Q: How do you know so much about planetariums?

    A: I’ve been working in planetariums for most of my life. I started presenting planetarium shows when I was about 10 or 11 in a small planetarium near Augsburg, which is about an hour from Munich, Germany. It is run by an association of volunteers and it was my first taste of these magical places. Of course in the beginning I worked in a voluntary capacity, but it also helps now that I am an engineer.

    Q: How is the ESO Supernova’s planetarium different to those you have previously worked in?

    A: It’s very different. The most obvious visible difference is that the ESO Supernova has an inclined dome — it is tilted by 25 degrees to allow for a better viewing experience. Overall, it’s a complex project, because we are actually implementing two different planetarium systems from Zeiss and Evans & Sutherland (E&S). The market of planetarium systems is a packed field, including Zeiss, E&S, and numerous others. All of them have their pros and cons. Our system looks a lot like a DJ deck — we have an audio mixer, spotlights, and lots of effects!

    4
    Max Rößner at the control board of the newly installed planetarium at the ESO Supernova Planetarium & Visitor Centre.
    Credit: ESO

    Another difference is that the ESO Supernova won’t use an optomechanical projector, usually used to project a nice starry sky. Instead, we are using a digital projection. Both types have positives and negatives. Optomechanical projectors are better at creating really precise stars — tiny, exact pinpricks of light. However, with the digital projection system there is much greater flexibility, and a much greater range in what we can show. For example, the presenter can even fly to a different location in space, which can’t be done with an optomechanical projector.

    Q: What kind of experience are you aiming to give visitors with these awesome systems?

    A: There is a joke in the planetarium world that people go to planetariums twice in their life: as a child and with their children. In the past, presenters generally gave a tour of the starry sky, including the Big Dipper and other famous constellations, and they would also point out some planets. But to match the expectations of audiences today, we use more advanced technology to create the kinds of shows that can also be continually updated to match modern science, and that are more personal and changeable.

    We want to avoid presenting a Hollywood-style film that has a clear beginning and neatly wrapped-up ending, so visitors just come, watch it and leave. Instead we want to create a dialogue with the audience, presenting each show with a more personal flair so each one is different. This can evolve depending on who is in the audience — such as their age or their background — and the questions people have throughout the show can also influence its direction.

    6
    The ESO Science Outreach Network (ESON) visited the ESO Supernova in 2017 and had a sneak-peek of some of the delights to come, learning more about the Extremely Large Telescope (ELT) on a test fulldome show. Credit: ESO/P. Horálek

    Q: You mentioned that the dome is tilted — why?

    A: This is a philosophical question. A tilted planetarium dome does make it a little more difficult to orient the audience, as people are used to using the Earth’s horizon as a reference point for celestial objects. For example, it is a little harder to demonstrate that the Sun rises in the east and sets in the west, because the sky itself isn’t tilted! But with the planetarium seats, which are raised up ‘diagonally’ on a slope like cinema seats, your brain does seem to correct for this.

    An advantage of the tilted dome is that people don’t have to look up very far, so they can look at the dome in a comfortable way and feel fully immersed in the show.

    A: There are a few technical and practical reasons for this:

    Ventilation: Fresh air comes in and used air goes out.
    Noise: We want the sound from within the planetarium to penetrate through the dome rather than bouncing off it completely, or we would end up with a chaotic chamber of echoing noise. The loudspeakers are also mounted behind the dome, and the sound needs to get through so we can hear it.
    Reflections: Similar to the problem of noise, we don’t want light to reflect around the dome from one area to another. The holes and the paint give the dome 58% reflectivity, reducing this problem.

    Q: How is content made differently for the curved screen of the planetarium?

    A: There are two ways to develop content for a planetarium. Firstly, to create films with a fisheye-like representation so they display correctly on the dome. In order to achieve this, a film is first split into the various projection fields, and then warped to compensate for the curved nature of the dome. These little pieces of the frame are then stored on individual PCs and fed to the different projectors.

    Live shows are another type of content. They are created and rendered on the spot, at the moment you present them. For example, we can show the sky as the visitors would see it now, outside. Tomorrow the Moon will change its position a little, and the Sun will set a bit later as we head towards spring, so we can adjust for these changes every day. This is a native functionality of Digistar, which is the planetarium system created by E&S. It’s a little like Google Maps, except with time, and showing the Universe.

    8
    With just a few months until the opening of the ESO Supernova Planetarium & Visitor Centre in spring 2018, the interior of the Centre is coming together.
    Credit: ESO/P. Horálek

    Q: What’s the day-to-day work like in a planetarium?

    A: It’s great! I love having some freedom in making design decisions and seeing those decisions realised. It’s exciting to see something you have planned and worked on for such a long time coming into reality, and to know that you are a big part of it.

    Q: What has been the biggest challenge so far?

    A: We’ve faced so many challenges. One memorable moment was when we were trying to test the software, but nothing happened. Nothing turned on, and we just saw a black sky above us. Of course, we panicked — but it turned out that we had left the dust caps on the projectors! So luckily, that didn’t turn out to be too challenging to fix. Even specialists make mistakes!

    An actual challenge was to raise awareness about our operational requirements. For example, we had to clearly communicate to the architects that we need a low horizon, room for equipment, extra sockets, space in the server room, and so on. Essentially, we were concerned about the practical side of running a planetarium with limited manpower and how that would be balanced with the architectural priorities of design and aesthetics.

    Then there’s the pressure from the fact that the project is dependent on me, because the software is absolutely fundamental to the working of the planetarium. One of the most difficult things has been getting the two planetarium systems to work together in a unified way. We need the added computational power of the second system to realise our operational goals.

    Of course, another challenge is that funding has been a limiting factor in some ways. Any project is easier when you have boundless amounts of money, but that’s not the reality here — especially since the ESO Supernova will be a free, open-source visitor centre.

    10
    A striking sunset shines upon the futuristic curves of the ESO Supernova Planetarium & Visitor Centre.
    Credit: P. Horálek/ESO

    Q: Another exciting part of the ESO Supernova project is the Data2Dome system. Tell us more about that.

    A: Up until now, planetariums have struggled to present really up-to-date content. First of all the content — such as new films, video clips or images — has to be found on the internet, then downloaded, then uploaded to the planetarium system. A script then has to be written to present alongside the content. This means it can take weeks for new research findings from around the world to reach planetariums’ audiences. Other mediums are way faster, like the internet, TV, and newspapers. So there was a problem: a planetarium is meant to be the competence centre of astronomical knowledge in a community, but it was lagging behind.

    We wanted to streamline the process of bringing research from astronomers to audiences around the world. ESO’s outreach department collaborated with E&S and the International Planetarium Society to come up with a technical standard: Data2Dome.

    Essentially, this helps scientific organisations publish their content in such a way that it enables planetarium vendors to download the content directly into their software. Manually shuffling and downloading data is bypassed. NASA, ESA, ESO and many others can directly stream their content into planetariums worldwide. It’s a free and open standard, first implemented by E&S. In particular, it’s great for smaller planetariums that may not have the time to continuously create new content.

    People are already using this software around the world — Data2Dome is streaming content to planetariums as we speak.

    Q: What are you looking forward to most once the ESO Supernova opens?

    A: It will be great to have the planetarium fully working and engaging with the audience. I feel the planetarium is my brainchild, so seeing it finally come to life will be amazing.

    Q: You’ve been working in planetariums for so many years — do you still feel excited when a show begins?

    A: Of course. This space holds a certain fascination that has never left me. I still get goosebumps. Emotion is a key part of the planetarium experience: shows are not just meant to teach you, but to touch you. When you think about it, the entire known Universe is stored in the computers downstairs at the ESO Supernova…so in a small dome on the edge of a city in Germany, we can leave Earth and travel to a different part of the Universe.

    See the full article here .

    Please help promote STEM in your local schools.
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    ESO is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive ground-based astronomical observatory by far. It is supported by 16 countries: Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Poland, Portugal, Spain, Sweden, Switzerland and the United Kingdom, along with the host state of Chile. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope, the world’s most advanced visible-light astronomical observatory and two survey telescopes. VISTA works in the infrared and is the world’s largest survey telescope and the VLT Survey Telescope is the largest telescope designed to exclusively survey the skies in visible light. ESO is a major partner in ALMA, the largest astronomical project in existence. And on Cerro Armazones, close to Paranal, ESO is building the 39-metre European Extremely Large Telescope, the E-ELT, which will become “the world’s biggest eye on the sky”.

    ESO LaSilla
    ESO/Cerro LaSilla 600 km north of Santiago de Chile at an altitude of 2400 metres.

    ESO VLT
    VLT at Cerro Paranal, with an elevation of 2,635 metres (8,645 ft) above sea level.

    ESO Vista Telescope
    ESO/Vista Telescope at Cerro Paranal, with an elevation of 2,635 metres (8,645 ft) above sea level.

    ESO NTT
    ESO/NTT at Cerro LaSilla 600 km north of Santiago de Chile at an altitude of 2400 metres.

    ESO VLT Survey telescope
    VLT Survey Telescope at Cerro Paranal with an elevation of 2,635 metres (8,645 ft) above sea level.

    ALMA Array
    ALMA on the Chajnantor plateau at 5,000 metres.

    ESO E-ELT
    ESO/E-ELT to be built at Cerro Armazones at 3,060 m.

    ESO APEX
    APEX Atacama Pathfinder 5,100 meters above sea level, at the Llano de Chajnantor Observatory in the Atacama desert.

    Leiden MASCARA instrument, La Silla, located in the southern Atacama Desert 600 kilometres (370 mi) north of Santiago de Chile at an altitude of 2,400 metres (7,900 ft)

    Leiden MASCARA cabinet at ESO Cerro la Silla located in the southern Atacama Desert 600 kilometres (370 mi) north of Santiago de Chile at an altitude of 2,400 metres (7,900 ft)

    ESO Next Generation Transit Survey at Cerro Paranel, 2,635 metres (8,645 ft) above sea level

    SPECULOOS four 1m-diameter robotic telescopes 2016 in the ESO Paranal Observatory, 2,635 metres (8,645 ft) above sea level

    ESO TAROT telescope at Paranal, 2,635 metres (8,645 ft) above sea level

    ESO ExTrA telescopes at Cerro LaSilla at an altitude of 2400 metres

     
  • richardmitnick 3:38 pm on February 9, 2018 Permalink | Reply
    Tags: , , , , ESOblog, Understanding How Stars Die   

    From ESOblog: “Understanding How Stars Die” 

    ESO 50 Large

    ESOblog

    Markus Wittkowski on using a team of telescopes to image dying stars

    9 February 2018

    1
    Science@ESO

    Over the centuries, astronomers have learned that stars are not just static pinpricks of light in the sky — they are dynamic and evolving objects that go through life cycles. Stars of different sizes evolve in different ways, and many processes of stellar evolution are still poorly understood. In a recent paper that appeared in Astronomy & Astrophysics, ESO astronomer Markus Wittkowski and his team imaged a star belonging to a particular group of old stars called AGB stars. We chatted to Markus to find out more.

    Q: So what are AGB stars and why did you want to study them?

    A: AGB stars, or asymptotic giant branch stars, are low- or intermediate-mass stars like our Sun that are at the end of their lives. At this stage, these stars have become red giants — they’re cooling off, creating extended atmospheres, and they’re losing a lot of mass in a dense stellar wind. They also periodically undergo pulses — about every 10 000 to 50 000 years — which blow material off the surface of the star at a much faster rate than normal. This helps create large shells of gas and dust, and eventually, these stars become planetary nebulae.

    We have a basic idea of this mass-loss process but we don’t know many details, in particular how this mass loss is initiated close to the surface of the star. So we wanted to find out more. Different types of AGB stars, like carbon-rich or oxygen-rich stars, have different properties. The mass-loss process is theoretically best understood for carbon-rich stars, so we decided to closely study the carbon-rich AGB star R Sculptoris — and our results are the start of a detailed understanding of what happens.

    Q: What can studying AGB stars tell us about the Universe?

    A: Studying AGB stars is important to understand stellar evolution. The amount of mass lost by the star actually changes its evolution and creates different types of planetary nebulae. Understanding these processes is important because AGB stars are one of the main producers of dust in the Universe, which means they enrich the Universe with elements.

    AGB stars are one part of the element-making puzzle because in the process of their death they can produce a vast range of elements — including 50% of elements heavier than iron. These elements are blown into the Universe to make new stars, new planets, new moons…to create the building blocks of everything else. To understand the stellar evolution process, we need to understand how these elements are created and released into the Universe.

    2
    Astronomers captured this ghostly image of AGB star R Sculptoris using ESO’s Very Large Telescope Interferometer (VLTI). The image covers a very small section of the sky: approximately 20×20 milliarcseconds. For comparison, Jupiter has an angular size of approximately 40 arcseconds.
    Credit: ESO/M. Wittkowski (ESO)

    Q: What did you find out?

    A: We were looking specifically at the region close to the stellar surface of the AGB star R Sculptoris, which is the region where mass-loss is initiated. We found that R Sculptoris has one dominant bright spot on its stellar disc, two or three times brighter than the other regions. This contrast is very large so we wondered how to explain it. We know that these stars have large convection cells of moving gas on their surface, but these wouldn’t produce such a large contrast. Moreover, for AGB stars we expect that such detailed structure would be obscured by the extended atmosphere and dense stellar wind. Previous radio observations of R Sculptoris with the Atacama Large Millimeter/submillimeter Array (ALMA) showed an interesting spiral structure within the stellar wind much further out from the star, which hints at the presence of a previously unknown companion star, cutting through the dust as it orbits. However, the distance to this companion is too large to cause the structure close to the surface of R Sculptoris that we observed.

    We compared our results to atmosphere and wind models, which predict that these convection cells on the photosphere are also related to mass loss and dust formation. This means that large convection cells with low contrast will lead to asymmetric dust formation — we’d get big blobs of dust forming, instead of a spherical dusty shell. This helped us to interpret our results: we realised we were seeing dust two or three stellar radii out from the star’s surface, forming not uniformly but in large clumps. The bright spot we saw is actually a spot where there is little to no dust, and we can look deeper into the stellar surface, where it’s brighter. The remaining parts appear darker because the starlight is blocked by the forming dust. Our “bright” spot is not actually inherently brighter, it’s simply a region that is less obscured by dust!

    Q: What makes R Sculptoris interesting to study?

    A: First of all, there aren’t many known carbon-rich AGB stars. We also needed to use a star that has the right size and the right brightness to observe it. As I mentioned, ALMA has previously found a spiral structure around R Sculptoris, which reveals a mass-loss history at much larger distances — the star had already thrown off large amounts of dust and transported it out to large distances.

    The spiral gives us a lot of information about the mass loss history, including how the mass was lost, at which rate, and at what velocity. The observations we took using the Very Large Telescope Interferometer (VLTI) are complementary to the ALMA observations. They show us the present state of the star because we can look directly at the part of the star where the dust forms, very close to the stellar surface. That’s too close for ALMA, which can only see the spiral of dust that occurs at distances a dozen of time larger.

    I also find the technique we used very exciting because we can use it to see the surface of stars, which until very recently we could only do for our own Sun.

    3
    ALMA observations revealed an unexpected spiral structure in the material around the old star R Sculptoris, probably caused by a hidden companion star orbiting the star.
    Credit: ALMA (ESO/NAOJ/NRAO)/M. Maercker et al.

    Q: Tell us more about the technique you used to make your observations.

    A: We used interferometric imaging to look at R Sculptoris. Imagine if you drop a stone into a lake and it makes a pattern of ripples radiating out through the water. Then you drop a second stone into a lake, which will create a second pattern, and the two will interfere at some point. This interference is what we’re interested in.

    Optical interferometry is like the double slit experiment that people do in high school physics, where you combine two beams coming from the same light source and look at the interference pattern produced. In interferometry at the Very Large Telescope, we combine light from different telescopes — sometimes up to a hundred metres apart — and it gives us a higher spatial resolution. It’s like observing a star with a 100-metre telescope. The resultant interference gives us information on very small spatial scales. If we combine a lot of these observations, we can actually reconstruct the image of the star.

    Interferometry is not an easy technique, but recent advances in observation efficiency and precision, as well as image-reconstruction techniques, allow us now to image stars other than the Sun. We tried several image-reconstruction methods and they all gave the same results, so we are quite confident that the images we reconstructed are correct.

    4
    Inside the tunnels housing instruments for the Very Large Telescope Interferometer (VLTI)
    Credit: ESO

    Q: Why do you need this technique to study these stars?

    A: Usually, if you look at a star with a single telescope, it’s so small that it appears to be a single point. From a single telescope, anything smaller than 30 to 60 milliarcseconds can’t be resolved. Astronomers use arcseconds to measure the angular sizes of objects on the sky; the Moon, for example, is around 30 arcminutes or 1800 arcseconds. Most stars are smaller than 30 to 60 milliarcseconds — R Sculptoris, for example, has an angular size of about 10 milliarcseconds, so it’s much smaller than what we could resolve with one telescope alone. But if we use interferometry to combine the observations of multiple telescopes, we can dramatically increase the resolution we can obtain! With the VLTI and its PIONIER instrument, we have observed scales of one or two milliarcseconds, so we can look at the details on the surface of the star.

    5
    One of the VLT’s Auxiliary Telescopes (AT) looks up at the stars of the Milky Way
    Credit: ESO/José Francisco Salgado (josefrancisco.org)

    Q: What’s next in this area of research?

    A: My colleagues and I are so excited about these imaging results coming out — not only for R Sculptoris but also for other similar stars, such as red giants and red supergiants, some with less dust around them. We’re getting a lot of new results in a lot of different wavelengths for more stars. We are now at a point where we can obtain resolved images of a variety of stars, so that’s quite exciting.

    We’re planning a workshop at ESO to discuss these results and put them all together. It’s a very exciting time at the moment because we can finally produce these images at different wavelengths. The models I mentioned are also progressing thanks to advances in computing power — we can now calculate and simulate the environment around a star, including the dust formation, in three-dimensions! You can see these clumps of dust in the models too, which is relatively new. So it’s a very exciting moment to bring all of these results together and plan the next steps.

    See the full article here .

    Please help promote STEM in your local schools.
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    ESO is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive ground-based astronomical observatory by far. It is supported by 16 countries: Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Poland, Portugal, Spain, Sweden, Switzerland and the United Kingdom, along with the host state of Chile. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope, the world’s most advanced visible-light astronomical observatory and two survey telescopes. VISTA works in the infrared and is the world’s largest survey telescope and the VLT Survey Telescope is the largest telescope designed to exclusively survey the skies in visible light. ESO is a major partner in ALMA, the largest astronomical project in existence. And on Cerro Armazones, close to Paranal, ESO is building the 39-metre European Extremely Large Telescope, the E-ELT, which will become “the world’s biggest eye on the sky”.

    ESO LaSilla
    ESO/Cerro LaSilla 600 km north of Santiago de Chile at an altitude of 2400 metres.

    ESO VLT
    VLT at Cerro Paranal, with an elevation of 2,635 metres (8,645 ft) above sea level.

    ESO Vista Telescope
    ESO/Vista Telescope at Cerro Paranal, with an elevation of 2,635 metres (8,645 ft) above sea level.

    ESO NTT
    ESO/NTT at Cerro LaSilla 600 km north of Santiago de Chile at an altitude of 2400 metres.

    ESO VLT Survey telescope
    VLT Survey Telescope at Cerro Paranal with an elevation of 2,635 metres (8,645 ft) above sea level.

    ALMA Array
    ALMA on the Chajnantor plateau at 5,000 metres.

    ESO E-ELT
    ESO/E-ELT to be built at Cerro Armazones at 3,060 m.

    ESO APEX
    APEX Atacama Pathfinder 5,100 meters above sea level, at the Llano de Chajnantor Observatory in the Atacama desert.

    Leiden MASCARA instrument, La Silla, located in the southern Atacama Desert 600 kilometres (370 mi) north of Santiago de Chile at an altitude of 2,400 metres (7,900 ft)

    Leiden MASCARA cabinet at ESO Cerro la Silla located in the southern Atacama Desert 600 kilometres (370 mi) north of Santiago de Chile at an altitude of 2,400 metres (7,900 ft)

    ESO Next Generation Transit Survey at Cerro Paranel, 2,635 metres (8,645 ft) above sea level

    SPECULOOS four 1m-diameter robotic telescopes 2016 in the ESO Paranal Observatory, 2,635 metres (8,645 ft) above sea level

    ESO TAROT telescope at Paranal, 2,635 metres (8,645 ft) above sea level

    ESO ExTrA telescopes at Cerro LaSilla at an altitude of 2400 metres

     
  • richardmitnick 9:54 pm on February 2, 2018 Permalink | Reply
    Tags: , , , , , ESOblog   

    From ESOblog: “Little Galaxies, Big Mysteries” 

    ESO 50 Large

    ESOblog

    2 February 2018

    1
    Science@ESO

    In order to understand some of the weirdest and most wonderful phenomena in the Universe, scientists rely on the Lambda Cold Dark Matter (LCDM) model. This model assumes the existence of dark matter and dark energy to explain things like the cosmic microwave background, the structure of galaxies, the abundances of elements and the accelerating expansion of the Universe. But recent research hints that this model might not explain everything. Astronomers have found a plane of dwarf galaxies orbiting Centaurus A, one of our closest galaxies — a discovery that challenges the long-held LCDM model. One of the team members is ESO astronomer Federico Lelli, so we chatted with him to find out more.

    Q: Firstly, what is a dwarf galaxy and why did you want to study them?

    A: Dwarf galaxies are the most numerous and most common types of galaxies in the Universe, but they are smaller and less massive than galaxies like our own Milky Way. The Milky Way, for example, contains about 100 billion stars, while dwarf galaxies may contain anywhere from a few thousand to “only” a billion stars. One famous example of a dwarf galaxy is the Small Magellanic Cloud, which is visible to the naked eye from the Southern Hemisphere. Dwarf galaxies are important in many aspects of astronomy, but to me they are particularly interesting because they can be used to test the currently most popular cosmological model, the Lambda Cold Dark Matter (LCDM) model, in which the mysterious dark matter and dark energy constitute more than 95% of the total mass-energy budget of the Universe.

    2
    An image from the Millennium-II Simulation, showing a central dark matter halo hosting a large galaxy, plus the surrounding dwarf galaxies.
    Credit: Boylan-Kolchin et al. (2009)

    Q: How can dwarf galaxies test the cosmological model?

    A: First of all, dwarf galaxies are thought to be heavily dominated by dark matter because they show large mass discrepancies. Let me explain what that means. By studying the motions of stars and gas within dwarf galaxies and using Newton’s gravitational law, we can estimate their total mass. But when we compare this number to the actual mass we see in stars and gas, the two numbers are vastly different — by a large factor, from tens to thousands depending on the object. We interpret this as evidence for large amounts of unseen dark matter inside dwarf galaxies. These galaxies are therefore prime natural laboratories to test different dark matter models or alternative gravity theories.

    Over the past ten years, however, people realised that we can also test our current cosmological model by looking at the distribution of dwarf satellites around their “host” galaxies and comparing that with the prediction of computer simulations based on the LCDM model.

    Q: Can you explain in more detail how this is done?

    A: According to the LCDM model, galaxies form at the centres of halos of dark matter. Using supercomputers, theoreticians can simulate the formation and growth of dark matter halos over time, from the Big Bang to the present day. It turns out that massive dark matter halos, which host bright galaxies, are generally surrounded by many smaller dark matter halos, which should host dwarf galaxies. The small halos are distributed in a random, nearly spherical fashion around the big one and move in a chaotic way, like bees around a hive. This is a neat prediction that can be tested by actually looking at the motions and positions of dwarf galaxies out in the Universe.

    Q: Have other researchers looked at this before?

    A: Sure, and the first results raised a big scientific debate. Arguably, the best-studied galaxies in the Universe are the Milky Way and its big neighbour, the Andromeda Galaxy. Both galaxies are surrounded by several dwarf satellites. But early research realised that these dwarfs are not distributed in a random way, as predicted by cosmological simulations. It was found that the satellites of the Milky Way lie in a narrow plane, which is perpendicular to the Milky Way’s disc, and they also seem to rotate within this plane — sort of like the planets around the Sun, except the orbits of dwarf galaxies are way more complex and uncertain. Imagine a pancake-like disc of dwarf galaxies, spinning around the Milky Way.

    Co-rotating planes of satellite galaxies are rare in cosmological simulations, occurring in less than 1% of simulated central dark matter halos, so people naturally thought that the Milky Way must be a bit of a weirdo. It was later discovered that the Andromeda Galaxy also hosts a plane of satellites, making this galaxy just as much of a weirdo as our own. At this point, people started to wonder whether the cosmological predictions are actually correct, or whether the Local Group of galaxies — including the Milky Way and the Andromeda Galaxy — is atypical and shouldn’t be used to test cosmology.

    Local Group. Andrew Z. Colvin 3 March 2011

    Q: How have you and your collaborators tried to answer these questions?

    A: We decided to look at satellite galaxies outside the Local Group to test whether the Milky Way and Andromeda are indeed atypical. We started with Centaurus A (also known as Cen A), which is a big elliptical galaxy in the constellation of Centaurus, about 13 million light-years away.

    3
    Centaurus A (NGC 5128)
    Date 28 January 2009
    Source http://www.eso.org/public/images/eso0903a/
    Author ESO/WFI (Optical); MPIfR/ESO/APEX/A.Weiss et al. (Submillimetre); NASA/CXC/CfA/R.Kraft et al. (X-ray)

    Colour composite image of Centaurus A, revealing the lobes and jets emanating from the active galaxy’s central black hole. This is a composite of images obtained with three instruments, operating at very different wavelengths. The 870-micron submillimetre data, from LABOCA on APEX, are shown in orange. X-ray data from the Chandra X-ray Observatory are shown in blue. Visible light data from the Wide Field Imager (WFI) on the MPG/ESO 2.2 m telescope located at La Silla, Chile, show the background stars and the galaxy’s characteristic dust lane in close to “true colour”.

    ESO/APEX high on the Chajnantor plateau in Chile’s Atacama region, at an altitude of over 4,800 m (15,700 ft)

    NASA/Chandra Telescope

    ESO WFI LaSilla 2.2-m MPG/ESO telescope at La Silla, 600 km north of Santiago de Chile at an altitude of 2400 metres


    MPG/ESO 2.2 meter telescope at Cerro La Silla, Chile, 600 km north of Santiago de Chile at an altitude of 2400 metres

    It’s surrounded by 31 dwarf satellites, plus another 15 candidates awaiting confirmation.

    The lead author of our Science paper — Oliver Müller from the University of Basel — has previously studied the Cen A system and found that the dwarf satellites are aligned along a plane. However, this specific planar geometry of Cen A occurs about 20% of the time in cosmological simulations (one out of five), so it didn’t seem too odd at first glance. But the picture changed drastically when we looked at the motions of the satellite galaxies.

    Q: What did you find?

    A: It turns out that the velocities of the satellite galaxies aren’t random, as we expected from cosmological simulations. After subtracting the so-called “recession velocity” due to the expansion of the Universe, the satellite galaxies to the south of Cen A are moving away from us, while the ones to the north of Cen A are approaching us. This is consistent with coherent rotation within the plane, similar to how the satellite dwarfs are moving around the Milky Way and the Andromeda Galaxy.

    Milky Way Galaxy Credits: NASA/JPL-Caltech/R. Hurt

    Andromeda Galaxy Adam Evans

    When we consider both the distribution and the motions of the satellite dwarfs, a configuration like Cen A becomes extremely rare in cosmological simulations: it has a probability of only 0.1%. In other words, we didn’t actually pick up a “weird” system out of thousands of “normal” ones — this can’t just be a coincidence. Instead, it seems likely that Cen A, Andromeda, and the Milky Way are normal galaxies after all, and that satellite planes are the rule rather than the exception. Perhaps there are many more planes of satellite galaxies out there just waiting to be discovered.


    Dwarf galaxies are arranged on a disc-shaped plane around the galaxy Centaurus A. Using the Doppler effect (a shift in spectral lines), their direction of motion and speed can be calculated. Credit: University of Basel/Oliver Müller

    Q: What are the major implications of this discovery?

    A: Essentially, our observations challenge the simulations. Planes of satellite dwarfs have been observed in all three major galaxies in the nearby Universe: the Milky Way, the Andromeda Galaxy, and now Cen A. This pattern is telling us something: since state-of-the-art cosmological simulations can’t explain how these planar structures are formed, perhaps we should start looking at alternatives.

    For example, there is an old idea from the Swiss astrophysicist Fritz Zwicky: dwarf galaxies may form during the encounter of two large galaxies, out of small debris that is ejected by tidal forces during the interaction. This idea was proposed again by the British astrophysicist Donald Lynden-Bell in the 1970s; he was one of the first to note the planar distribution of dwarf galaxies around the Milky Way and to point out that galaxy encounters may naturally explain such geometries and coherent motions. Dwarf galaxies formed in this way, however, should be free of dark matter, so people lost interest in such an idea as the predominant dark matter paradigm took over. Our results indicate that such “old” ideas deserve a closer look.

    4
    Here we see the result of the merger between two spiral galaxies, forming a central elliptical-like object called NGC 7252 with two large tidal tails. Tidal dwarf galaxies are currently forming within these tails. The optical image is overlaid with the gas distribution (blue) and ultraviolet emission (violet), probing the recent formation of new stars and highlighting the location of tidal dwarfs. Credit: Lelli et al. 2015, A&A

    Q: Did you face any challenges in your research?

    A: The observational aspect of this work was relatively easy because we used existing data. The velocities of the dwarf satellites were measured before by other authors using various facilities and techniques. We “only” had to collect and analyse them. The challenging part was to compare reality with simulations, taking into account possible observational biases and uncertainties. In particular, we considered two large public simulations. One — called Millennium II — uses only dark matter particles and neglects the possible effect of “baryonic processes”, like the formation of stars, supernova explosions, and so on. The other — called Illustris — tries to model these complex baryonic processes to form actual galaxies inside dark matter halos. However, both simulations give essentially the same result as far as the distribution and kinematics of dwarf satellites are concerned.

    Q: What do you personally find most exciting about this research topic?

    A: The current cosmological model is quite successful in explaining the Universe on large scales. However, it needs to postulate two unknown substances: dark matter and dark energy. Challenging the cosmological model on small scales is one way to move forward with our understanding of dark matter and fundamental physics.

    Q: So what’s your next step?

    A: Next, we will measure distances and velocities of more candidate dwarf galaxies around Cen A. This will improve our statistics and allow for a more accurate comparison with cosmological simulations. We will also look for similar planar structures around other large galaxies in the Universe.

    See the full article here .

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