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  • richardmitnick 6:12 am on May 20, 2015 Permalink | Reply
    Tags: , , ESO VLT   

    From ESO: “The Dreadful Beauty of Medusa” 


    European Southern Observatory

    20 May 2015
    Richard Hook
    ESO Public Information Officer
    Garching bei München, Germany
    Tel: +49 89 3200 6655
    Cell: +49 151 1537 3591
    Email: rhook@eso.org

    1

    Astronomers using ESO’s Very Large Telescope in Chile have captured the most detailed image ever taken of the Medusa Nebula. As the star at the heart of this nebula made its transition into retirement, it shed its outer layers into space, forming this colourful cloud. The image foreshadows the final fate of the Sun, which will eventually also become an object of this kind.

    This beautiful planetary nebula is named after a dreadful creature from Greek mythology — the Gorgon Medusa. It is also known as Sharpless 2-274 and is located in the constellation of Gemini (The Twins). The Medusa Nebula spans approximately four light-years and lies at a distance of about 1500 light-years. Despite its size it is extremely dim and hard to observe.

    Medusa was a hideous creature with snakes in place of hair. These snakes are represented by the serpentine filaments of glowing gas in this nebula. The red glow from hydrogen and the fainter green emission from oxygen gas extends well beyond this frame, forming a crescent shape in the sky. The ejection of mass from stars at this stage of their evolution is often intermittent, which can result in fascinating structures within planetary nebulae.

    For tens of thousands of years the stellar cores of planetary nebulae are surrounded by these spectacularly colourful clouds of gas [1]. Over a further few thousand years the gas slowly disperses into its surroundings. This is the last phase in the transformation of stars like the Sun before ending their active lives as white dwarfs. The planetary nebula stage in the life of a star is a tiny fraction of its total life span — just as the time a child takes to blow a soap bubble and see it drift away is a brief instant compared to a full human life span.

    Harsh ultraviolet radiation from the very hot star at the core of the nebula causes atoms in the outward-moving gas to lose their electrons, leaving behind ionised gas. The characteristic colours of this glowing gas can be used to identify objects. In particular, the presence of the green glow from doubly ionised oxygen ([O III]) is used as a tool for spotting planetary nebulae. By applying appropriate filters, astronomers can isolate the radiation from the glowing gas and make the dim nebulae appear more pronounced against a darker background.

    When the green [O III] emission from nebulae was first observed, astronomers thought they had discovered a new element that they dubbed nebulium. They later realised that it was simply a rare wavelength of radiation [2] from an ionised form of the familiar element oxygen.

    The nebula is also referred to as Abell 21 (more formally PN A66 21), after the American astronomer George O. Abell, who discovered this object in 1955. For some time scientists debated whether the cloud could be the remnant of a supernova explosion. In the 1970s, however, researchers were able to measure the movement and other properties of the material in the cloud and clearly identify it as a planetary nebula [3].

    This image uses data from the FOcal Reducer and low dispersion Spectrograph (FORS) instrument attached to the VLT, which were acquired as part of the ESO Cosmic Gems programme [4].

    ESO FORS1
    FORS1

    Notes

    [1] Counterintuitively, the stellar core of the Medusa Nebula is not the bright star in the centre of this image — this is a foreground star called TYC 776-1339-1. Medusa’s central star is a dimmer, bluish star lying just off-centre of the crescent shape and in the right-hand part of this image.

    [2] This type of radiation is rare because it is created by a forbidden mechanism — transitions that are forbidden by quantum selection rules, but can still occur with a low probability. The designation [O III] means that the radiation is forbidden (the square brackets) emission from doubly ionised (the III part of the name) oxygen (O).

    [3] The expansion velocity of the cloud was found to be about 50 kilometres/second — much lower than would be expected for a supernova remnant.

    [4] The ESO Cosmic Gems programme is an outreach initiative to produce images of interesting, intriguing or visually attractive objects using ESO telescopes, for the purposes of education and public outreach. The programme makes use of telescope time that cannot be used for science observations. All data collected may also be suitable for scientific purposes, and are made available to astronomers through ESO’s science archive.

    See the full article here.

    Another view

    2
    Medusa nebula, 24 inch telescope on Mt. Lemmon, AZ. Courtesy of Joseph D. Schulman

    Mt Lemon 24 inch telescope
    24″ telescope at Mt Lemmon

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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
    LaSilla

    ESO VLT Interferometer
    VLT

    ESO Vista Telescope
    VISTA

    ESO VLT Survey telescope
    VLT Survey Telescope

    ALMA Array
    ALMA

    ESO E-ELT
    E-ELT

    ESO APEX
    Atacama Pathfinder Experiment (APEX) Telescope

     
  • richardmitnick 5:47 am on May 13, 2015 Permalink | Reply
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    From ESO: “The Dark Side of Star Clusters” 


    European Southern Observatory

    13 May 2015
    Contacts
    Matthew A. Taylor
    Pontificia Universidad Catolica de Chile
    Santiago, Chile
    Tel: +56-9-91912386
    Email: mataylor5128@gmail.com

    Thomas H. Puzia
    Pontificia Universidad Catolica de Chile
    Santiago, Chile
    Tel: +56-9-89010007
    Email: tpuzia@gmail.com

    Richard Hook
    ESO, Public Information Officer
    Garching bei München, Germany
    Tel: +49 89 3200 6655
    Cell: +49 151 1537 3591
    Email: rhook@eso.org

    1

    Observations with ESO’s Very Large Telescope in Chile have discovered a new class of “dark” globular star clusters around the giant galaxy Centaurus A. These mysterious objects look similar to normal clusters, but contain much more mass and may either harbour unexpected amounts of dark matter, or contain massive black holes — neither of which was expected nor is understood.

    Globular star clusters are huge balls of thousands of stars that orbit most galaxies. They are among the oldest known stellar systems in the Universe and have survived through almost the entire span of galaxy growth and evolution.

    Matt Taylor, a PhD student at the Pontificia Universidad Catolica de Chile, Santiago, Chile, and holder of an ESO Studentship, is lead author of the new study. He sets the scene: “Globular clusters and their constituent stars are keys to understanding the formation and evolution of galaxies. For decades, astronomers thought that the stars that made up a given globular cluster all shared the same ages and chemical compositions — but we now know that they are stranger and more complicated creatures.”

    The elliptical galaxy Centaurus A (also known as NGC 5128) is the closest giant galaxy to the Milky Way and is suspected to harbour as many as 2000 globular clusters. Many of these globulars are brighter and more massive than the 150 or so orbiting the Milky Way.

    2
    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”.
    Date 28 January 2009

    ESO LABOCA
    LABOCA

    ESO APEX
    APEX

    NASA Chandra Telescope
    NASA/Chandra

    ESO WFI LaSilla
    WFI

    ESO 2.2 meter telescope
    MPG/ESO 2.2 m telescope

    Matt Taylor and his team have now made the most detailed studies so far of a sample of 125 globular star clusters around Centaurus A using the FLAMES instrument on ESO’s Very Large Telescope at the Paranal Observatory in northern Chile [1].

    ESO FLAMES
    FLAMES

    They used these observations to deduce the mass of the clusters [2] and compare this result with how brightly each of the clusters shines.

    For most of the clusters in the new survey, the brighter ones had more mass in the way that was expected — if a cluster contains more stars it has greater total brightness and more total mass. But for some of the globulars something strange showed up: they were many times more massive than they looked. And even more strangely, the more massive these unusual clusters were, the greater the fraction of their material was dark. Something in these clusters was dark, hidden and massive. But what?

    There were several possibilities. Perhaps the dark clusters contain black holes, or other dark stellar remnants in their cores? This may be a factor that explains some of the hidden mass, but the team concludes that it cannot be the whole story. What about dark matter? Globular clusters are normally considered to be almost devoid of this mysterious substance, but perhaps, for some unknown reason, some clusters have retained significant dark matter clumps in their cores. This would explain the observations but does not fit into conventional theory.

    Co-author Thomas Puzia adds: “Our discovery of star clusters with unexpectedly high masses for the amount of stars they contain hints that there might be multiple families of globular clusters, with differing formation histories. Apparently some star clusters look like, walk like, and smell like run-of-the-mill globulars, but there may quite literally be more to them than meets the eye.”

    These objects remain a mystery. The team is also engaged in a wider survey of other globular clusters in other galaxies and there are some intriguing hints that such dark clusters may also be found elsewhere.

    Matt Taylor sums up the situation: “We have stumbled on a new and mysterious class of star cluster! This shows that we still have much to learn about all aspects of globular cluster formation. It’s an important result and we now need to find further examples of dark clusters around other galaxies.”

    Notes

    [1] Up to now astronomers have studied star clusters to this detail only in the Local Group. The relatively small distances make direct measurements of their masses possible. Looking at NGC 5128, which is an isolated, massive elliptical galaxy just outside the Local Group about 12 million light-years away, they were able to estimate masses of globular clusters in a completely different environment by pushing VLT/FLAMES to its limits.

    [2] The FLAMES observations provide information about the motions of the stars in the clusters. This orbital information depends on the strength of the gravitational field and can hence be used to deduce the mass of the cluster — astronomers call such estimates dynamical masses. The light gathering power of a 8.2-metre VLT Unit Telescope mirror and FLAMES’s ability to observe more than 100 clusters simultaneously was the key to collecting the data necessary for the study.
    More information

    This research was presented in a paper entitled Observational evidence for a dark side to NGC 5128’s globular cluster system, by M. Taylor et al., to appear in the Astrophysical Journal.

    The team is composed of Matthew A. Taylor (Pontificia Universidad Catolica de Chile, Santiago, Chile; ESO, Santiago, Chile), Thomas H. Puzia (Pontificia Universidad Catolica de Chile), Matias Gomez (Universidad Andres Bello, Santiago, Chile) and Kristin A. Woodley (University of California, Santa Cruz, California, USA).

    See the full article here.

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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
    LaSilla

    ESO VLT Interferometer
    VLT

    ESO Vista Telescope
    VISTA

    ESO VLT Survey telescope
    VLT Survey Telescope

    ALMA Array
    ALMA

    ESO E-ELT
    E-ELT

    ESO APEX
    Atacama Pathfinder Experiment (APEX) Telescope

     
  • richardmitnick 10:51 am on April 30, 2015 Permalink | Reply
    Tags: , , ESO MUSE, ESO VLT,   

    From ESO- ESOcast 72: “Looking Deeply into the Universe in 3D” 


    European Southern Observatory

    The MUSE instrument on ESO’s Very Large Telescope has given astronomers the best ever three-dimensional view of the deep Universe. After staring at the Hubble Deep Field South region for a total of 27 hours the new observations reveal the distances, motions and other properties of far more galaxies than ever before in this tiny piece of the sky. But they also go beyond Hubble and reveal many previously unseen objects.

    ESO Muse2
    MUSE

    ESO VLT
    VLT


    Watch, enjoy, Learn

    See the full article here.

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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
    LaSilla

    ESO VLT Interferometer
    VLT

    ESO Vista Telescope
    VISTA

    ESO VLT Survey telescope
    VLT Survey Telescope

    ALMA Array
    ALMA

    ESO E-ELT
    E-ELT

    ESO APEX
    Atacama Pathfinder Experiment (APEX) Telescope

     
  • richardmitnick 5:57 am on April 30, 2015 Permalink | Reply
    Tags: , , ESO VLT   

    From ESO: “The Pillars of Creation Revealed in 3D” 


    European Southern Observatory

    30 April 2015
    Anna Faye Mc Leod
    ESO
    Garching bei München, Germany
    Tel: +49 89 3200 6321
    Email: amcleod@eso.org

    Richard Hook
    ESO, Public Information Officer
    Garching bei München, Germany
    Tel: +49 89 3200 6655
    Cell: +49 151 1537 3591
    Email: rhook@eso.org

    Temp 1

    4
    Colour composite view of the Pillars of Creation from MUSE data

    5
    The three-dimensional view of the Pillars of Creation from MUSE

    Using the MUSE instrument on ESO’s Very Large Telescope (VLT), astronomers have produced the first complete three-dimensional view of the famous Pillars of Creation in the Eagle Nebula, Messier 16. The new observations demonstrate how the different dusty pillars of this iconic object are distributed in space and reveal many new details — including a previously unseen jet from a young star. Intense radiation and stellar winds from the cluster’s brilliant stars have sculpted the dusty Pillars of Creation over time and should fully evaporate them in about three million years.

    2
    This wide-field image of the Eagle Nebula was taken at the National Science Foundation’s WIYN 0.9-meter telescope on Kitt Peak with the NOAO Mosaic CCD camera. Located in the constellation of Serpens, the Serpent, the Eagle Nebula is a very luminous open cluster of stars surrounded by dust and gas. The three pillars at the center of the image, made famous in an image by the Hubble Space Telescope, are being sculpted by the intense radiation from the hot stars in the cluster. This image was created by combining emission-line images in Hydrogen-alpha (green), Oxygen [O III] (blue) and Sulfur [S II] (red).

    NOAO WIYN .9 meter Telescope
    NOAO WIYN .9 meter telescope at Kitt Peak

    The original NASA/ESA Hubble Space Telescope image of the famous Pillars of Creation was taken two decades ago and immediately became one of its most famous and evocative pictures. Since then, these billowing clouds, which extend over a few light-years [1], have awed scientists and the public alike.

    NASA Hubble Telescope
    Hubble

    2
    Star forming pillars in the Eagle Nebula, as seen by the Hubble Space Telescope’s WFPC2 [No longer in service]. The picture is composed of 32 different images from four separate cameras in this instrument. The photograph was made with light emitted by different elements in the cloud and appears as a different colour in the composite image: green for hydrogen, red for singly-ionized sulphur and blue for double-ionized oxygen atoms. The missing part at the top right is because one of the four cameras has a magnified view of its portion, which allows astronomers to see finer detail. The images from this camera were scaled down in size to match those from the other three cameras. Further information at: Credit: NASA, Jeff Hester, and Paul Scowen (Arizona State University)
    Date circa 2003 (HST image is from 1995)

    NASA Hubble WFPC2
    WFPC2

    The jutting structures, along with the nearby star cluster, NGC 6611, are parts of a star formation region called the Eagle Nebula, also known as Messier 16 or M16. The nebula and its associated objects are located about 7000 light-years away in the constellation of Serpens (The Serpent).

    The Pillars of Creation are a classic example of the column-like shapes that develop in the giant clouds of gas and dust that are the birthplaces of new stars. The columns arise when immense, freshly formed blue–white O and B stars give off intense ultraviolet radiation and stellar winds that blow away less dense materials from their vicinity.

    Denser pockets of gas and dust, however, can resist this erosion for longer. Behind such thicker dust pockets, material is shielded from the harsh, withering glare of O and B stars. This shielding creates dark “tails” or “elephant trunks”, which we see as the dusky body of a pillar, that point away from the brilliant stars.

    ESO’s MUSE instrument on the Very Large Telescope has now helped illustrate the ongoing evaporation of the Pillars of Creation in unprecedented detail, revealing their orientation.

    ESO Muse2
    MUSE

    MUSE has shown that the tip of the left pillar is facing us, atop a pillar that is is actually situated behind NGC 6611, unlike the other pillars. This tip is bearing the brunt of the radiation from NGC 6611’s stars, and as a result looks brighter to our eyes than the bottom left, middle and right pillars, whose tips are all pointed away from our view.

    Astronomers hope to better understand how young O and B stars like those in NGC 6611 influence the formation of subsequent stars. Numerous studies have identified protostars forming in these clouds — they are indeed Pillars of Creation. The new study also reports fresh evidence for two gestating stars in the left and middle pillars as well as a jet from a young star that had escaped attention up to now.

    For more stars to form in environments like the Pillars of Creation, it is a race against time as intense radiation from the powerful stars that are already shining continues to grind away at the pillars.

    By measuring the Pillars of Creation’s rate of evaporation, MUSE has given astronomers a time frame for when the pillars will be no more. They shed about 70 times the mass of the Sun every million years or so. Based on the their present mass of about 200 times that of the Sun, the Pillars of Creation have an expected lifetime of perhaps three million more years — an eyeblink in cosmic time. It seems that an equally apt name for these iconic cosmic columns might be the Pillars of Destruction.

    Notes

    [1] The left pillar, considered as a complete object from top to bottom, is estimated to be about four light-years in length. It is the longest pillar and about twice the height of the right pillar.
    More information

    This research was presented in a paper entitled The Pillars of Creation revisited with MUSE: gas kinematics and high-mass stellar feedback traced by optical spectroscopy by A. F. McLeod et al., to appear in the journal Monthly Notices of the Royal Astronomical Society on 30 April 2015.

    The team is composed of A. F. Mc Leod (ESO, Garching, Germany), J. E. Dale (Universitäts-Sternwarte München, München, Germany; Excellence Cluster Universe, Garching bei München, Germany), A. Ginsburg (ESO), B. Ercolano (Universitats-Sternwarte München,; Excellence Cluster Universe), M. Gritschneder (Universitats-Sternwarte München), S. Ramsay (ESO) and L. Testi (ESO; INAF/Osservatorio Astrofisico di Arcetri, Firenze, Italy).

    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
    LaSilla

    ESO VLT Interferometer
    VLT

    ESO Vista Telescope
    VISTA

    ESO VLT Survey telescope
    VLT Survey Telescope

    ALMA Array
    ALMA

    ESO E-ELT
    E-ELT

    ESO APEX
    Atacama Pathfinder Experiment (APEX) Telescope

     
  • richardmitnick 3:17 pm on April 16, 2015 Permalink | Reply
    Tags: , , ESO VLT,   

    From ESO: “Giant Galaxies Die from the Inside Out” 


    European Southern Observatory

    16 April 2015
    Sandro Tacchella
    ETH Zurich
    Zurich, Switzerland
    Tel: +41 44 633 6314
    Cell: +41 76 480 7963
    Email: sandro.tacchella@phys.ethz.ch

    Marcella Carollo
    ETH Zurich
    Zurich, Switzerland
    Tel: +41 797 926 581
    Email: marcella@phys.ethz.ch

    Richard Hook
    ESO, Public Information Officer
    Garching bei München, Germany
    Tel: +49 89 3200 6655
    Cell: +49 151 1537 3591
    Email: rhook@eso.org

    VLT and Hubble observations show that star formation shuts down in the centres of elliptical galaxies first

    Temp 1

    Astronomers have shown for the first time how star formation in “dead” galaxies sputtered out billions of years ago. ESO’s Very Large Telescope and the NASA/ESA Hubble Space Telescope have revealed that three billion years after the Big Bang, these galaxies still made stars on their outskirts, but no longer in their interiors. The quenching of star formation seems to have started in the cores of the galaxies and then spread to the outer parts. The results will be published in the 17 April 2015 issue of the journal Science.

    A major astrophysical mystery has centred on how massive, quiescent elliptical galaxies, common in the modern Universe, quenched their once furious rates of star formation. Such colossal galaxies, often also called spheroids because of their shape, typically pack in stars ten times as densely in the central regions as in our home galaxy, the Milky Way, and have about ten times its mass.

    Astronomers refer to these big galaxies as red and dead as they exhibit an ample abundance of ancient red stars, but lack young blue stars and show no evidence of new star formation. The estimated ages of the red stars suggest that their host galaxies ceased to make new stars about ten billion years ago. This shutdown began right at the peak of star formation in the Universe, when many galaxies were still giving birth to stars at a pace about twenty times faster than nowadays.

    “Massive dead spheroids contain about half of all the stars that the Universe has produced during its entire life,” said Sandro Tacchella of ETH Zurich in Switzerland, lead author of the article. “We cannot claim to understand how the Universe evolved and became as we see it today unless we understand how these galaxies come to be.”

    Tacchella and colleagues observed a total of 22 galaxies, spanning a range of masses, from an era about three billion years after the Big Bang [1]. The SINFONI instrument on ESO’s Very Large Telescope (VLT) collected light from this sample of galaxies, showing precisely where they were churning out new stars. SINFONI could make these detailed measurements of distant galaxies thanks to its adaptive optics system, which largely cancels out the blurring effects of Earth’s atmosphere.

    ESO SINFONI
    SINFONI

    The researchers also trained the NASA/ESA Hubble Space Telescope on the same set of galaxies, taking advantage of the telescope’s location in space above our planet’s distorting atmosphere. Hubble’s WFC3 camera snapped images in the near-infrared, revealing the spatial distribution of older stars within the actively star-forming galaxies.

    NASA Hubble Telescope
    NASA/ESA Hubble

    “What is amazing is that SINFONI’s adaptive optics system can largely beat down atmospheric effects and gather information on where the new stars are being born, and do so with precisely the same accuracy as Hubble allows for the stellar mass distributions,” commented Marcella Carollo, also of ETH Zurich and co-author of the study.

    According to the new data, the most massive galaxies in the sample kept up a steady production of new stars in their peripheries. In their bulging, densely packed centres, however, star formation had already stopped.

    “The newly demonstrated inside-out nature of star formation shutdown in massive galaxies should shed light on the underlying mechanisms involved, which astronomers have long debated,” says Alvio Renzini, Padova Observatory, of the Italian National Institute of Astrophysics.

    A leading theory is that star-making materials are scattered by torrents of energy released by a galaxy’s central supermassive black hole as it sloppily devours matter. Another idea is that fresh gas stops flowing into a galaxy, starving it of fuel for new stars and transforming it into a red and dead spheroid.

    “There are many different theoretical suggestions for the physical mechanisms that led to the death of the massive spheroids,” said co-author Natascha Förster Schreiber, at the Max-Planck-Institut für extraterrestrische Physik in Garching, Germany. “Discovering that the quenching of star formation started from the centres and marched its way outwards is a very important step towards understanding how the Universe came to look like it does now.”

    Notes

    [1] The Universe’s age is about 13.8 billion years, so the galaxies studied by Tacchella and colleagues are generally seen as they were more than 10 billion years ago.
    More information

    This research was presented in a paper entitled Evidence for mature bulges and an inside-out quenching phase 3 billion years after the Big Bang by S. Tacchella et al., to appear in the journal Science on 17 April 2015.

    The team is composed of Sandro Tacchella (ETH Zurich, Switzerland), Marcella Carollo (ETH Zurich), Alvio Renzini (Italian National Institute of Astrophysics, Padua, Italy), Natascha Förster Schreiber (Max-Planck-Institut für Extraterrestrische Physik, Garching, Germany), Philipp Lang (Max-Planck-Institut für Extraterrestrische Physik), Stijn Wuyts (Max-Planck-Institut für Extraterrestrische Physik), Giovanni Cresci (Istituto Nazionale di Astrofisica), Avishai Dekel (The Hebrew University, Israel), Reinhard Genzel (Max-Planck-Institut für extraterrestrische Physik and University of California, Berkeley, California, USA), Simon Lilly (ETH Zurich), Chiara Mancini (Italian National Institute of Astrophysics), Sarah Newman (University of California, Berkeley, California, USA), Masato Onodera (ETH Zurich), Alice Shapley (University of California, Los Angeles, USA), Linda Tacconi (Max-Planck-Institut für Extraterrestrische Physik, Garching, Germany), Joanna Woo (ETH Zurich) and Giovanni Zamorani (Italian National Institute of Astrophysics, Bologna, Italy).

    See the full article here.

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  • richardmitnick 6:18 pm on April 14, 2015 Permalink | Reply
    Tags: , , ESO VLT   

    From ESO: “First Signs of Self-interacting Dark Matter?” 


    European Southern Observatory

    15 April 2015
    Richard Massey
    Institute for Computational Cosmology
    Durham University, United Kingdom
    Tel: +44 (0) 7740 648080
    Email: r.j.massey@durham.ac.uk

    Richard Hook
    ESO, Public Information Officer
    Garching bei München, Germany
    Tel: +49 89 3200 6655
    Cell: +49 151 1537 3591
    Email: rhook@eso.org

    Dark matter may not be completely dark after all

    1

    For the first time dark matter may have been observed interacting with other dark matter in a way other than through the force of gravity. Observations of colliding galaxies made with ESO’s Very Large Telescope and the NASA/ESA Hubble Space Telescope have picked up the first intriguing hints about the nature of this mysterious component of the Universe.

    Using the MUSE instrument on ESO’s VLT in Chile, along with images from Hubble in orbit, a team of astronomers studied the simultaneous collision of four galaxies in the galaxy cluster Abell 3827. The team could trace out where the mass lies within the system and compare the distribution of the dark matter with the positions of the luminous galaxies.

    ESO MUSE
    MUSE

    NASA Hubble Telescope
    NASA/ESA Hubble

    Although dark matter cannot be seen, the team could deduce its location using a technique called gravitational lensing. The collision happened to take place directly in front of a much more distant, unrelated source. The mass of dark matter around the colliding galaxies severely distorted spacetime, deviating the path of light rays coming from the distant background galaxy — and distorting its image into characteristic arc shapes.

    Our current understanding is that all galaxies exist inside clumps of dark matter. Without the constraining effect of dark matter’s gravity, galaxies like the Milky Way would fling themselves apart as they rotate. In order to prevent this, 85 percent of the Universe’s mass [1] must exist as dark matter, and yet its true nature remains a mystery.

    In this study, the researchers observed the four colliding galaxies and found that one dark matter clump appeared to be lagging behind the galaxy it surrounds. The dark matter is currently 5000 light-years (50 000 million million kilometres) behind the galaxy — it would take NASA’s Voyager spacecraft 90 million years to travel that far.

    NASA Voyager 1
    NASA/Voyager 1

    A lag between dark matter and its associated galaxy is predicted during collisions if dark matter interacts with itself, even very slightly, through forces other than gravity [2]. Dark matter has never before been observed interacting in any way other than through the force of gravity.

    Lead author Richard Massey at Durham University, explains: “We used to think that dark matter just sits around, minding its own business, except for its gravitational pull. But if dark matter were being slowed down during this collision, it could be the first evidence for rich physics in the dark sector — the hidden Universe all around us.”

    The researchers note that more investigation will be needed into other effects that could also produce a lag. Similar observations of more galaxies, and computer simulations of galaxy collisions will need to be made.

    Team member Liliya Williams of the University of Minnesota adds: “We know that dark matter exists because of the way that it interacts gravitationally, helping to shape the Universe, but we still know embarrassingly little about what dark matter actually is. Our observation suggests that dark matter might interact with forces other than gravity, meaning we could rule out some key theories about what dark matter might be.”

    This result follows on from a recent result from the team which observed 72 collisions between galaxy clusters [3] and found that dark matter interacts very little with itself. The new work however concerns the motion of individual galaxies, rather than clusters of galaxies. Researchers say that the collision between these galaxies could have lasted longer than the collisions observed in the previous study — allowing the effects of even a tiny frictional force to build up over time and create a measurable lag [4].

    Taken together, the two results bracket the behaviour of dark matter for the first time. Dark matter interacts more than this, but less than that. Massey added: “We are finally homing in on dark matter from above and below — squeezing our knowledge from two directions.”
    Notes

    [1] Astronomers have found that the total mass/energy content of the Universe is split in the proportions 68% dark energy, 27% dark matter and 5% “normal” matter. So the 85% figure relates to the fraction of “matter” that is dark.

    [2] Computer simulations show that the extra friction from the collision would make the dark matter slow down. The nature of that interaction is unknown; it could be caused by well-known effects or some exotic unknown force. All that can be said at this point is that it is not gravity.

    All four galaxies might have been separated from their dark matter. But we happen to have a very good measurement from only one galaxy, because it is by chance aligned so well with the background, gravitationally lensed object. With the other three galaxies, the lensed images are further away, so the constraints on the location of their dark matter too loose to draw statistically significant conclusions.

    [3] Galaxy clusters contain up to a thousand individual galaxies.

    [4] The main uncertainty in the result is the timespan for the collision: the friction that slowed the dark matter could have been a very weak force acting over about a billion years, or a relatively stronger force acting for “only” 100 million years.
    More information

    This research was presented in a paper entitled The behaviour of dark matter associated with 4 bright cluster galaxies located in the 10 kpc core of Abell 3827 to appear in the journal Monthly Notices of the Royal Astronomical Society on 15 April 2015.

    The team is composed of R. Massey (Institute for Computational Cosmology, Durham University, Durham, UK), L. Williams (School of Physics & Astronomy, University of Minnesota, Minneapolis, Minnesota, USA), R. Smit (Institute for Computational Cosmology, UK), M. Swinbank (Institute for Computational Cosmology, UK), T. D. Kitching (Mullard Space Science Laboratory, University College London, Dorking, Surrey, UK), D. Harvey (Ecole Polytechnique Fédérale de Lausanne, Observatoire de Sauverny, Versoix, Switzerland), H. Israel (Institute for Computational Cosmology, UK), M. Jauzac (Institute for Computational Cosmology, UK; Astrophysics and Cosmology Research Unit, School of Mathematical Sciences, University of KwaZulu-Natal, Durban, South Africa), D. Clowe (Department of Physics and Astronomy, Ohio University, Athens, Ohio, USA), A. Edge (Department of Physics, Durham University, Durham, UK), M. Hilton (Astrophysics and Cosmology Research Unit, South Africa), E. Jullo (Laboratoire d’Astrophysique de Marseille, Université d’Aix-Marseille, Marseille, France), A. Leonard (University College London, London, UK), J. Liesenborgs (Hasselt University, Diepenbeek, Belgium), J. Merten (Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA; California Institute of Technology, Pasadena, California, USA), I. Mohammed (Physik-Institüt, University of Zürich, Zürich, Switzerland), D. Nagai (Department of Physics, Yale University, New Haven, Connecticut, USA), J. Richard (Observatoire de Lyon, Université Lyon, Saint Genis Laval, France), A. Robertson (Institute for Computational Cosmology, UK), P. Saha (Physik-Institüt, Switzerland), R. Santana (Department of Physics and Astronomy, Ohio University, Athens, Ohio, USA), J. Stott (Department of Physics, Durham, UK) and E. Tittley (Royal Observatory, Edinburgh, UK).

    See the full article here.

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  • richardmitnick 6:46 am on March 26, 2015 Permalink | Reply
    Tags: , , , ESO VLT   

    From ESO: “Best View Yet of Dusty Cloud Passing Galactic Centre Black Hole” 


    European Southern Observatory

    26 March 2015
    Andreas Eckart
    University of Cologne
    Cologne, Germany
    Email: eckart@ph1.uni-koeln.de

    Monica Valencia-S.
    University of Cologne
    Cologne, Germany
    Email: mvalencias@ph1.uni-koeln.de

    Richard Hook
    ESO, Public Information Officer
    Garching bei München, Germany
    Tel: +49 89 3200 6655
    Cell: +49 151 1537 3591
    Email: rhook@eso.org

    VLT observations confirm that G2 survived close approach and is a compact object

    Temp 0

    The best observations so far of the dusty gas cloud G2 confirm that it made its closest approach to the supermassive black hole at the centre of the Milky Way in May 2014 and has survived the experience. The new result from ESO’s Very Large Telescope shows that the object appears not to have been significantly stretched and that it is very compact. It is most likely to be a young star with a massive core that is still accreting material. The black hole itself has not yet shown any increase in activity.

    A supermassive black hole with a mass four million times that of the Sun lies at the heart of the Milky Way galaxy. It is orbited by a small group of bright stars and, in addition, an enigmatic dusty cloud, known as G2, has been tracked on its fall towards the black hole over the last few years. Closest approach, known as peribothron, was predicted to be in May 2014.

    The great tidal forces in this region of very strong gravity were expected to tear the cloud apart and disperse it along its orbit. Some of this material would feed the black hole and lead to sudden flaring and other evidence of the monster enjoying a rare meal. To study these unique events, the region at the galactic centre has been very carefully observed over the last few years by many teams using large telescopes around the world.

    A team led by Andreas Eckart (University of Cologne, Germany) has observed the region using ESO’s Very Large Telescope (VLT) [1] over many years, including new observations during the critical period from February to September 2014, just before and after the peribothron event in May 2014. These new observations are consistent with earlier ones made using the Keck Telescope on Hawaii [2].

    Keck Observatory
    Keck Observatory Interior
    UCO/Keck

    The images of infrared light coming from glowing hydrogen show that the cloud was compact both before and after its closest approach, as it swung around the black hole.

    As well as providing very sharp images, the SINFONI instrument on the VLT also splits the light into its component infrared colours and hence allows the velocity of the cloud to be estimated [3].

    ESO SINFONI
    SINFONI

    Before closest approach, the cloud was found to be travelling away from the Earth at about ten million kilometres/hour and, after swinging around the black hole, it was measured to be approaching the Earth at about twelve million kilometres/hour.

    Florian Peissker, a PhD student at the University of Cologne in Germany, who did much of the observing, says: “Being at the telescope and seeing the data arriving in real time was a fascinating experience,” and Monica Valencia-S., a post-doctoral researcher also at the University of Cologne, who then worked on the challenging data processing adds: “It was amazing to see that the glow from the dusty cloud stayed compact before and after the close approach to the black hole.”

    Although earlier observations had suggested that the G2 object was being stretched, the new observations did not show evidence that the cloud had become significantly smeared out, either by becoming visibly extended, or by showing a larger spread of velocities.

    In addition to the observations with the SINFONI instrument the team has also made a long series of measurements of the polarisation of the light coming from the supermassive black hole region using the NACO instrument on the VLT.

    ESO NACO
    NACO

    These, the best such observations so far, reveal that the behaviour of the material being accreted onto the black hole is very stable, and — so far — has not been disrupted by the arrival of material from the G2 cloud.

    The resilience of the dusty cloud to the extreme gravitational tidal effects so close to the black hole strongly suggest that it surrounds a dense object with a massive core, rather than being a free-floating cloud. This is also supported by the lack, so far, of evidence that the central monster is being fed with material, which would lead to flaring and increased activity.

    Andreas Eckart sums up the new results: “We looked at all the recent data and in particular the period in 2014 when the closest approach to the black hole took place. We cannot confirm any significant stretching of the source. It certainly does not behave like a coreless dust cloud. We think it must be a dust-shrouded young star.”

    Notes

    [1] These are very difficult observations as the region is hidden behind thick dust clouds, requiring observations in infrared light. And, in addition, the events occur very close to the black hole, requiring adaptive optics to get sharp enough images. The team used the SINFONI instrument on ESO’s Very Large Telescope and also monitored the behaviour of the central black hole region in polarised light using the NACO instrument.

    [2] The VLT observations are both sharper (because they are made at shorter wavelengths) and also have additional measurements of velocity from SINFONI and polarisation measurement using the NACO instrument.

    [3] Because the dusty cloud is moving relative to Earth — away from Earth before closest approach to the black hole and towards Earth afterwards — the Doppler shift changes the observed wavelength of light. These changes in wavelength can be measured using a sensitive spectrograph such as the SINFONI instrument on the VLT. It can also be used to measure the spread of velocities of the material, which would be expected if the cloud was extended along its orbit to a significant extent, as had previously been reported.

    More information

    This research was presented in a paper Monitoring the Dusty S-Cluster Object (DSO/G2) on its Orbit towards the Galactic Center Black Hole by M. Valencia-S. et al. in the journal Astrophysical Journal Letters.

    The team is composed of M. Valencia-S. (Physikalisches Institut der Universität zu Köln, Germany), A. Eckart (Universität zu Köln; Max-Planck-Institut für Radioastronomie, Bonn, Germany [MPIfR]), M. Zajacek (Universität zu Köln; MPIfR; Astronomical Institute of the Academy of Sciences Prague, Czech Republic), F. Peissker (Universität zu Köln), M. Parsa (Universität zu Köln), N. Grosso (Observatoire Astronomique de Strasbourg, France), E. Mossoux (Observatoire Astronomique de Strasbourg), D. Porquet (Observatoire Astronomique de Strasbourg), B. Jalali (Universität zu Köln), V. Karas (Astronomical Institute of the Academy of Sciences Prague), S. Yazici (Universität zu Köln), B. Shahzamanian (Universität zu Köln), N. Sabha (Universität zu Köln), R. Saalfeld (Universität zu Köln), S. Smajic (Universität zu Köln), R. Grellmann (Universität zu Köln), L. Moser (Universität zu Köln), M. Horrobin (Universität zu Köln), A. Borkar (Universität zu Köln), M. García-Marín (Universität zu Köln), M. Dovciak (Astronomical Institute of the Academy of Sciences Prague), D. Kunneriath (Astronomical Institute of the Academy of Sciences Prague), G. D. Karssen (Universität zu Köln), M. Bursa (Astronomical Institute of the Academy of Sciences Prague), C. Straubmeier (Universität zu Köln) and H. Bushouse (Space Telescope Science Institute, Baltimore, Maryland, USA).

    See the full article here.

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  • richardmitnick 7:24 pm on March 2, 2015 Permalink | Reply
    Tags: , , , ESO VLT, Infrared Astronomy,   

    From ESO And ALMA: “An Old-looking Galaxy in a Young Universe” 

    ESO ALMA Array
    ESO/NRAO/NAOJ/ALMA
    ALMA


    European Southern Observatory

    ESO VLT Interferometer
    ESO/VLT

    2 March 2015

    Valeria Foncea
    Education and Public Outreach Officer
    Joint ALMA Observatory
    Santiago, Chile
    Tel: +56 2 467 6258
    Cell: +56 9 75871963
    Email: vfoncea@alma.cl

    Masaaki Hiramatsu
    Education and Public Outreach Officer, NAOJ Chile
    Observatory Tokyo, Japan
    Tel: +81 422 34 3630
    E-mail: hiramatsu.masaaki@nao.ac.jp

    Charles E. Blue
    Public Information Officer
    National Radio Astronomy Observatory
    Charlottesville, Virginia, USA
    Tel: +1 434 296 0314
    Cell: +1 434.242.9559
    E-mail: cblue@nrao.edu

    Darach Watson
    Niels Bohr Institute
    University of Copenhagen, Denmark
    Tel: +45 2480 3825
    Email: darach@dark-cosmology.dk

    Kirsten K. Knudsen
    Chalmers University of Technology
    Onsala, Sweden
    Tel: +46 31 772 5526
    Cell: +46 709 750 956
    Email: kirsten.knudsen@chalmers.se

    Richard Hook
    ESO education and Public Outreach Department
    Garching bei München, Germany
    Tel: +49 89 3200 6655
    Cell: +49 151 1537 3591
    Email: rhook@eso.org

    temp0

    One of the most distant galaxies ever observed has provided astronomers with the first detection of dust in such a remote star-forming system and tantalising evidence for the rapid evolution of galaxies after the Big Bang. The new observations have used ALMA to pick up the faint glow from cold dust in the galaxy A1689-zD1 and used ESO’s Very Large Telescope to measure its distance.

    A team of astronomers, led by Darach Watson from the University of Copenhagen, used the Very Large Telescope’s X-shooter instrument along with the Atacama Large Millimeter/submillimeter Array (ALMA) to observe one of the youngest and most remote galaxies ever found.

    ESO VLT X-shooter
    X-shooter

    They were surprised to discover a far more evolved system than expected. It had a fraction of dust similar to a very mature galaxy, such as the Milky Way. Such dust is vital to life, because it helps form planets, complex molecules and normal stars.

    The target of their observations is called A1689-zD1 [1]. It is observable only by virtue of its brightness being amplified more than nine times by a gravitational lens in the form of the spectacular galaxy cluster, Abell 1689, which lies between the young galaxy and the Earth. Without the gravitational boost, the glow from this very faint galaxy would have been too weak to detect.

    We are seeing A1689-zD1 when the Universe was only about 700 million years old — five percent of its present age [2]. It is a relatively modest system — much less massive and luminous than many other objects that have been studied before at this stage in the early Universe and hence a more typical example of a galaxy at that time.

    8

    A1689-zD1 is being observed as it was during the period of reionisation, when the earliest stars brought with them a cosmic dawn, illuminating for the first time an immense and transparent Universe and ending the extended stagnation of the [cosmic] Dark Ages. Expected to look like a newly formed system, the galaxy surprised the observers with its rich chemical complexity and abundance of interstellar dust.

    “After confirming the galaxy’s distance using the VLT,” said Darach Watson, “we realised it had previously been observed with ALMA. We didn’t expect to find much, but I can tell you we were all quite excited when we realised that not only had ALMA observed it, but that there was a clear detection. One of the main goals of the ALMA Observatory was to find galaxies in the early Universe from their cold gas and dust emissions — and here we had it!”

    This galaxy was a cosmic infant — but it proved to be precocious. At this age it would be expected to display a lack of heavier chemical elements — anything heavier than hydrogen and helium, defined in astronomy as metals. These are produced in the bellies of stars and scattered far and wide once the stars explode or otherwise perish. This process needs to be repeated for many stellar generations to produce a significant abundance of the heavier elements such as carbon, oxygen and nitrogen.

    Surprisingly, the galaxy A1689-zD1 seemed to be emitting a lot of radiation in the far infrared [3], indicating that it had already produced many of its stars and significant quantities of metals, and revealed that it not only contained dust, but had a dust-to-gas ratio that was similar to that of much more mature galaxies.

    “Although the exact origin of galactic dust remains obscure,” explains Darach Watson, “our findings indicate that its production occurs very rapidly, within only 500 million years of the beginning of star formation in the Universe — a very short cosmological time frame, given that most stars live for billions of years.”

    The findings suggest A1689-zD1 to have been consistently forming stars at a moderate rate since 560 million years after the Big Bang, or else to have passed through its period of extreme starburst very rapidly before entering a declining state of star formation.

    Prior to this result, there had been concerns among astronomers that such distant galaxies would not be detectable in this way, but A1689-zD1 was detected using only brief observations with ALMA.

    Kirsten Knudsen (Chalmers University of Technology, Sweden), co-author of the paper, added, “This amazingly dusty galaxy seems to have been in a rush to make its first generations of stars. In the future, ALMA will be able to help us to find more galaxies like this, and learn just what makes them so keen to grow up.”
    Notes

    [1] This galaxy was noticed earlier in the Hubble images, and suspected to be very distant, but the distance could not be confirmed at that time.

    [2] This corresponds to a redshift of 7.5.

    [3] This radiation is stretched by the expansion of the Universe into the millimetre wavelength range by the time it gets to Earth and hence can be detected with ALMA.
    More information

    This research was presented in a paper entitled A dusty, normal galaxy in the epoch of reionization by D. Watson et al., to appear online in the journal Nature on 2 March 2015.

    The team is composed of D. Watson (Niels Bohr Institute, University of Copenhagen, Denmark), L. Christensen (University of Copenhagen), K. K. Knudsen (Chalmers University of Technology, Sweden), J. Richard (CRAL, Observatoire de Lyon, Saint Genis Laval, France), A. Gallazzi (INAF-Osservatorio Astrofisico di Arcetri, Firenze, Italy) and M. J. Michalowski (SUPA, Institute for Astronomy, University of Edinburgh, Royal Observatory, Edinburgh, UK).

    See the full article here.

    Hubble’s results

    2
    Abell 1689
    This new Hubble image shows galaxy cluster Abell 1689. It combines both visible and infrared data from Hubble’s Advanced Camera for Surveys (ACS) with a combined exposure time of over 34 hours (image on left over 13 hours, image on right over 20 hours) to reveal this patch of sky in greater and striking detail than in previous observations.

    This image is peppered with glowing golden clumps, bright stars, and distant, ethereal spiral galaxies. Material from some of these galaxies is being stripped away, giving the impression that the galaxy is dripping, or bleeding, into the surrounding space. Also visible are a number of electric blue streaks, circling and arcing around the fuzzy galaxies in the centre.
    These streaks are the telltale signs of a cosmic phenomenon known as gravitational lensing. Abell 1689 is so massive that it bends and warps the space around it, affecting how light from objects behind the cluster travels through space. These streaks are the distorted forms of galaxies that lie behind the cluster.
    Date 12 September 2013
    NASA, ESA, the Hubble Heritage Team (STScI/AURA), J. Blakeslee (NRC Herzberg Astrophysics Program, Dominion Astrophysical Observatory), and H. Ford (JHU)

    NASA Hubble Telescope
    Hubble

    NASA Hubble ACS
    Hubble’s ACS

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    ESO, European Southern Observatory, builds and operates a suite of the world’s most advanced ground-based astronomical telescopes.

    The Atacama Large Millimeter/submillimeter Array (ALMA), an international astronomy facility, is a partnership of Europe, North America and East Asia in cooperation with the Republic of Chile. ALMA is funded in Europe by the European Organization for Astronomical Research in the Southern Hemisphere (ESO), in North America by the U.S. National Science Foundation (NSF) in cooperation with the National Research Council of Canada (NRC) and the National Science Council of Taiwan (NSC) and in East Asia by the National Institutes of Natural Sciences (NINS) of Japan in cooperation with the Academia Sinica (AS) in Taiwan.

    ALMA construction and operations are led on behalf of Europe by ESO, on behalf of North America by the National Radio Astronomy Observatory (NRAO), which is managed by Associated Universities, Inc. (AUI) and on behalf of East Asia by the National Astronomical Observatory of Japan (NAOJ). The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA.

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  • richardmitnick 7:21 am on February 26, 2015 Permalink | Reply
    Tags: , , ESO VLT   

    From ESO: “Looking Deeply into the Universe in 3D 


    European Southern Observatory

    26 February 2015
    Roland Bacon
    CRAL – Centre de recherche astrophysique de Lyon
    Saint-Genis-Laval, France
    Tel: +33 478 86 85 59
    Cell: +33 608 09 14 27
    Email: roland.bacon@univ-lyon1.fr

    Richard Hook
    ESO education and Public Outreach Department
    Garching bei München, Germany
    Tel: +49 89 3200 6655
    Cell: +49 151 1537 3591
    Email: rhook@eso.org

    temp0

    The MUSE instrument on ESO’s Very Large Telescope has given astronomers the best ever three-dimensional view of the deep Universe. After staring at the Hubble Deep Field South region for only 27 hours, the new observations reveal the distances, motions and other properties of far more galaxies than ever before in this tiny piece of the sky. They also go beyond Hubble and reveal previously invisible objects.
    MUSE

    ESO MUSE

    ESO VLT Interferometer
    VLT

    By taking very long exposure pictures of regions of the sky, astronomers have created many deep fields that have revealed much about the early Universe. The most famous of these was the original Hubble Deep Field, taken by the NASA/ESA Hubble Space Telescope over several days in late 1995. This spectacular and iconic picture rapidly transformed our understanding of the content of the Universe when it was young. It was followed two years later by a similar view in the southern sky — the Hubble Deep Field South.

    NASA Hubble Deep Field
    Hubble Deep Field

    NASA Hubble Telescope
    Hubble

    But these images did not hold all the answers — to find out more about the galaxies in the deep field images, astronomers had to carefully look at each one with other instruments, a difficult and time-consuming job. But now, for the first time, the new MUSE instrument can do both jobs at once — and far more quickly.

    One of the first observations using MUSE after it was commissioned on the VLT in 2014 was a long hard look at the Hubble Deep Field South (HDF-S). The results exceeded expectations.

    temp0

    “After just a few hours of observations at the telescope, we had a quick look at the data and found many galaxies — it was very encouraging. And when we got back to Europe we started exploring the data in more detail. It was like fishing in deep water and each new catch generated a lot of excitement and discussion of the species we were finding,” explained Roland Bacon (Centre de Recherche Astrophysique de Lyon, France, CNRS) principal investigator of the MUSE instrument and leader of the commissioning team.

    For every part of the MUSE view of HDF-S there is not just a pixel in an image, but also a spectrum revealing the intensity of the light’s different component colours at that point — about 90 000 spectra in total [1]. These can reveal the distance, composition and internal motions of hundreds of distant galaxies — as well as catching a small number of very faint stars in the Milky Way.

    Even though the total exposure time was much shorter than for the Hubble images, the HDF-S MUSE data revealed more than twenty very faint objects in this small patch of the sky that Hubble did not record at all [2].

    “The greatest excitement came when we found very distant galaxies that were not even visible in the deepest Hubble image. After so many years of hard work on the instrument, it was a powerful experience for me to see our dreams becoming reality,” adds Roland Bacon.

    By looking carefully at all the spectra in the MUSE observations of the HDF-S, the team measured the distances to 189 galaxies. They ranged from some that were relatively close, right out to some that were seen when the Universe was less than one billion years old. This is more than ten times the number of measurements of distance than had existed before for this area of sky.

    For the closer galaxies, MUSE can do far more and look at the different properties of different parts of the same galaxy. This reveals how the galaxy is rotating and how other properties vary from place to place. This is a powerful way of understanding how galaxies evolve through cosmic time.

    “Now that we have demonstrated MUSE’s unique capabilities for exploring the deep Universe, we are going to look at other deep fields, such as the Hubble Ultra Deep field. We will be able to study thousands of galaxies and to discover new extremely faint and distant galaxies. These small infant galaxies, seen as they were more than 10 billion years in the past, gradually grew up to become galaxies like the Milky Way that we see today,” concludes Roland Bacon.
    Notes

    [1] Each spectrum covers a range of wavelengths from the blue part of the spectrum into the near-infrared (475‒930 nanometres).

    [2] MUSE is particularly sensitive to objects that emit most of their energy at a few particular wavelengths as these show up as bright spots in the data. Galaxies in the early Universe typically have such spectra, as they contain hydrogen gas glowing under the ultraviolet radiation from hot young stars.
    More information

    This research was presented in a paper entitled The MUSE 3D view of the Hubble Deep Field South by R. Bacon et al., to appear in the journal Astronomy & Astrophysics on 26 February 2015.

    The team is composed of R. Bacon (Observatoire de Lyon, CNRS, Université Lyon, Saint Genis Laval, France [Lyon]), J. Brinchmann (Leiden Observatory, Leiden University, Leiden, The Netherlands [Leiden]), J. Richard (Lyon), T. Contini (Institut de Recherche en Astrophysique et Planétologie, CNRS, Toulouse, France; Université de Toulouse, France [IRAP]), A. Drake (Lyon), M. Franx (Leiden), S. Tacchella (ETH Zurich, Institute of Astronomy, Zurich, Switzerland [ETH]), J. Vernet (ESO, Garching, Germany), L. Wisotzki (Leibniz-Institut für Astrophysik Potsdam, Potsdam, Germany [AIP]), J. Blaizot (Lyon), N. Bouché (IRAP), R. Bouwens (Leiden), S. Cantalupo (ETH), C.M. Carollo (ETH), D. Carton (Leiden), J. Caruana (AIP), B. Clément (Lyon), S. Dreizler (Institut für Astrophysik, Universität Göttingen, Göttingen, Germany [AIG]), B. Epinat (IRAP; Aix Marseille Université, CNRS, Laboratoire d’Astrophysique de Marseille, Marseille, France), B. Guiderdoni (Lyon), C. Herenz (AIP), T.-O. Husser (AIG), S. Kamann (AIG), J. Kerutt (AIP), W. Kollatschny (AIG), D. Krajnovic (AIP), S. Lilly (ETH), T. Martinsson (Leiden), L. Michel-Dansac (Lyon), V. Patricio (Lyon), J. Schaye (Leiden), M. Shirazi (ETH), K. Soto (ETH), G. Soucail (IRAP), M. Steinmetz (AIP), T. Urrutia (AIP), P. Weilbacher (AIP) and T. de Zeeuw (ESO, Garching, Germany; Leiden).

    See the full article here.

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  • richardmitnick 10:32 am on February 18, 2015 Permalink | Reply
    Tags: , , ESO VLT   

    From ESO: “The Strange Case of the Missing Dwarf” 


    European Southern Observatory

    18 February 2015
    Adam Hardy
    Universidad Valparaíso
    Valparaíso, Chile
    Tel: +56 32 2508457
    Email: adam.hardy@postgrado.uv.cl

    Matthias Schreiber
    Universidad de Valparaíso
    Valparaíso, Chile
    Tel: +56 32 2399279
    Email: matthias@dfa.uv.cl

    Richard Hook
    ESO education and Public Outreach Department
    Garching bei München, Germany
    Tel: +49 89 3200 6655
    Cell: +49 151 1537 3591
    Email: rhook@eso.org

    New SPHERE instrument shows its power

    ESO SPHERE New

    The new SPHERE instrument on ESO’s Very Large Telescope has been used to search for a brown dwarf expected to be orbiting the unusual double star V471 Tauri.

    ESO VLT Interferometer
    ESO/VLT

    SPHERE has given astronomers the best look so far at the surroundings of this intriguing object and they found — nothing. The surprising absence of this confidently predicted brown dwarf means that the conventional explanation for the odd behaviour of V471 Tauri is wrong. This unexpected result is described in the first science paper based on observations from SPHERE.

    Some pairs of stars consist of two normal stars with slightly different masses. When the star of slightly higher mass ages and expands to become a red giant, material is transferred to other star and ends up surrounding both stars in a huge gaseous envelope. When this cloud disperses the two move closer together and form a very tight pair with one white dwarf, and one more normal star [1].

    One such stellar pair is called V471 Tauri [2]. It is a member of the Hyades star cluster in the constellation of Taurus and is estimated to be around 600 million years old and about 163 light-years from Earth.

    2
    Hyades star cluster

    The two stars are very close and orbit each other every 12 hours. Twice per orbit one star passes in front of the other — which leads to regular changes in the brightness of the pair observed from Earth as they eclipse each other.

    A team of astronomers led by Adam Hardy (Universidad Valparaíso, Valparaíso, Chile) first used the ULTRACAM system on ESO’s New Technology Telescope to measure these brightness changes very precisely. The times of the eclipses were measured with an accuracy of better than two seconds — a big improvement on earlier measurements.

    ESO VLT ULTRACAM
    ULTRACAM

    ESO NTT
    ESO NTT Interior
    ESO/NTT

    The eclipse timings were not regular, but could be explained well by assuming that there was a brown dwarf orbiting both stars whose gravitational pull was disturbing the orbits of the stars. They also found hints that there might be a second small companion object.

    Up to now however, it has been impossible to actually image a faint brown dwarf so close to much brighter stars. But the power of the newly installed SPHERE instrument on ESO’s Very Large Telescope allowed the team to look for the first time exactly where the brown dwarf companion was expected to be. But they saw nothing, even though the very high quality images from SPHERE should have easily revealed it [3].

    “There are many papers suggesting the existence of such circumbinary objects, but the results here provide damaging evidence against this hypothesis,” remarks Adam Hardy.

    If there is no orbiting object then what is causing the odd changes to the orbit of the binary? Several theories have been proposed, and, while some of these have already been ruled out, it is possible that the effects are caused by magnetic field variations in the larger of the two stars [4], somewhat similar to the smaller changes seen in the Sun.

    “A study such as this has been necessary for many years, but has only become possible with the advent of powerful new instruments such as SPHERE. This is how science works: observations with new technology can either confirm, or as in this case disprove, earlier ideas. This is an excellent way to start the observational life of this amazing instrument,” concludes Adam Hardy.
    Notes

    [1] Such pairs are known as post-common-envelope binaries.

    [2] This name means that the object is the 471st variable star (or as closer analysis shows, pair of stars) to be identified in the constellation of Taurus.

    [3] The SPHERE images are so accurate that they would have been able to reveal a companion such as a brown dwarf that is 70 000 times fainter than the central star, and only 0.26 arcseconds away from it. The expected brown dwarf companion in this case was predicted to be much brighter.

    [4] This effect is called the Applegate mechanism and results in regular changes in the shape of the star, which can lead to changes in the apparent brightness of the double star seen from Earth.

    More information

    This research was presented in a paper entitled The First Science Results from SPHERE: Disproving the Predicted Brown Dwarf around V471 Tau by A. Hardy et al., to appear in the Astrophysical Journal Letters on 18 February 2015.

    The team is composed of A. Hardy (Universidad Valparaíso, Valparaíso, Chile; Millennium Nucleus “Protoplanetary Disks in ALMA Early Science”, part of the Millennium Science Initiative Program, Universidad Valparaíso), M.R. Schreiber (Universidad Valparaíso), S.G. Parsons (Universidad Valparaíso), C. Caceres (Universidad Valparaíso), G. Retamales (Universidad Valparaíso), Z. Wahhaj (ESO, Santiago, Chile), D. Mawet (ESO, Santiago, Chile), H. Canovas (Universidad Valparaíso), L. Cieza (Universidad Diego Portales, Santiago, Chile; Universidad Valparaíso), T.R. Marsh (University of Warwick, Coventry, United Kingdom), M.C.P. Bours (University of Warwick), V.S. Dhillon (University of Sheffield, Sheffield, United Kingdom) and A. Bayo (Universidad Valparaíso).

    See the full article here.

    Please help promote STEM in your local schools.
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    Visit ESO in Social Media-

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    Twitter

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    ESO, European Southern Observatory, builds and operates a suite of the world’s most advanced ground-based astronomical telescopes.

     
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