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  • richardmitnick 4:15 pm on June 29, 2017 Permalink | Reply
    Tags: , , ESO Pale Red Dot Project, , The Case for Cosmic Modesty,   

    From SA: “The Case for Cosmic Modesty” 

    Scientific American

    Scientific American

    June 28, 2017
    Abraham Loeb

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    The Parkes radio telescope in Australia has been used to search for extraterrestrial intelligence. Credit: Ian Sutton Flickr (CC BY-SA 3.0)

    “There are many reasons to be modest,” my mother used to say when I was a kid. But after three decades as an astronomer, I can add one more reason: the richness of the universe around us.

    Universe map Sloan Digital Sky Survey (SDSS) 2dF Galaxy Redshift Survey

    Prior to the development of modern astronomy, humans tended to think the physical world centered on us. The sun and the stars were thought to revolve around Earth. Although naive in retrospect, this is a natural starting point. When my daughters were infants, they tended to think the world centered on them. Their development portrayed an accelerated miniature of human history. As they grew up, they matured and acquired a more balanced perspective.

    Similarly, observing the sky makes us aware of the big picture and teaches us modesty. We now know we are not at the center of the physical universe, because Earth orbits the sun, which circles around the center of the Milky Way Galaxy, which itself drifts with a peculiar velocity of ~0.001c (c is the speed of light) relative to the cosmic rest frame.

    Milky Way NASA/JPL-Caltech /ESO R. Hurt

    Many people, however, still believe we might be at the center of the biological universe; namely, that life is rare or unique to Earth. In contrast, my working hypothesis, drawn from the above example of the physical universe, is that we are not special in general, not only in terms of our physical coordinates but also as a form of life. Adopting this perspective implies we are not alone. There should be life out there in both primitive and intelligent forms. This conclusion, implied by the principle of “cosmic modesty,” has implications. If life is likely to exist elsewhere, we should search for it in all of its possible forms.

    Breakthrough Listen Project

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    Lick Automated Planet Finder telescope, Mount Hamilton, CA, USA



    GBO radio telescope, Green Bank, West Virginia, USA

    CSIRO/Parkes Observatory, located 20 kilometres north of the town of Parkes, New South Wales, Australia

    Breakthrough Starshot Initiative

    Breakthrough Starshot

    ESO 3.6m telescope & HARPS at LaSilla, 600 km north of Santiago de Chile at an altitude of 2400 metres.

    SPACEOBS, the San Pedro de Atacama Celestial Explorations Observatory is located at 2450m above sea level, north of the Atacama Desert, in Chile, near to the village of San Pedro de Atacama and close to the border with Bolivia and Argentina

    SNO Sierra Nevada Observatory is a high elevation observatory 2900m above the sea level located in the Sierra Nevada mountain range in Granada Spain and operated maintained and supplied by IAC

    Teide Observatory in Tenerife Spain, home of two 40 cm LCO telescopes

    Observatori Astronòmic del Montsec (OAdM), located in the town of Sant Esteve de la Sarga (Pallars Jussà), 1,570 meters on the sea level

    Bayfordbury Observatory,approximately 6 miles from the main campus of the University of Hertfordshire

    Our civilization has reached an important milestone. We now have access to unprecedented technologies in our search for extraterrestrial life, be it primitive or intelligent. The search for primitive life is currently underway and well funded, but the search for intelligence is out of the mainstream of federal funding agencies. This should not be the case given that the only planet known to host life, Earth, shows both primitive and intelligent life forms of it.

    Our first radio signals have leaked by now out to a distance of more than 100 light-years and we might soon hear back a response. Rather than being guided by Fermi’s paradox: “Where is everybody?” or by philosophical arguments about the rarity of intelligence, we should invest funds in building better observatories and searching for a wide variety of artificial signals in the sky. Civilizations at our technological level might produce mostly weak signals. For example, a nuclear war on the nearest planet outside the solar system would not be visible even with our largest telescopes.

    But very advanced civilizations could potentially be detectable out to the edge of the observable universe through their most powerful beacons. The evidence for an alien civilization might not be in the traditional form of radio communication signals. Rather, it could involve detecting artifacts on planets via the spectral edge from solar cells, industrial pollution of atmospheres, artificial lights or bursts of radiation from artificial beams sweeping across the sky.

    Finding the answer to the important question: “Are we alone?” will change our perspective on our place in the universe and will open new interdisciplinary fields of research, such as astrolinguistics (how to communicate with aliens), astropolitics (how to negotiate with them for information), astrosociology (how to interpret their collective behavior), astroeconomics (how to trade space-based resources) and so on. We could shortcut our own progress by learning from civilizations that benefited from a head start of billions of years.

    There is no doubt that noticing the big picture taught my young daughters modesty. Similarly, the Kepler space telescope survey of nearby stars allowed astronomers to infer there are probably more habitable Earth-mass planets in the observable volume of the universe than there are grains of sand on all beaches on Earth. Emperors or kings who boasted after conquering a piece of land on Earth resemble an ant that hugs with great pride a single grain of sand on the landscape of a huge beach.

    Just over the past year, astronomers discovered a potentially habitable planet, Proxima b, around the nearest star, Proxima Centauri as well as three potentially habitable planets out of seven around another nearby star TRAPPIST-1.

    ESO Pale Red Dot project

    ESO Red Dots Campaign

    Centauris Alpha Beta Proxima 27, February 2012. Skatebiker

    The TRAPPIST-1 star, an ultracool dwarf, is orbited by seven Earth-size planets (NASA).

    ESO Belgian robotic Trappist National Telescope at Cerro La Silla, Chile interior

    ESO Belgian robotic Trappist-South National Telescope at Cerro La Silla, Chile

    (And if life formed on one of the three, it was likely transferred to the others.) These dwarf stars, whose masses are 12 percent and 8 percent the sun’s mass, respectively, will live for up to 10 trillion years, about a thousand times longer than the sun. Hence, they provide excellent prospects for life in the distant future, long after the sun will die and turn into a cool white dwarf.

    I therefore advise my wealthy friends to buy real estate on Proxima b, because its value will likely go up dramatically in the future. But this also raises an important scientific question: “Is life most likely to emerge at the present cosmic time near a star like the sun?” By surveying the habitability of the universe throughout cosmic history from the birth of the first stars 30 million years after the big bang to the death of the last stars in 10 trillion years, one reaches the conclusion that unless habitability around low-mass stars is suppressed, life is most likely to exist near red dwarf stars like Proxima Centauri or TRAPPIST-1 trillions of years from now.

    The chemistry of “life as we know it” requires liquid water, but being at the right distance from the host star for achieving a comfortable temperature on the planet’s surface is not a sufficient condition for life. The planet also needs to have an atmosphere. In the absence of an external atmospheric pressure, warming by starlight would transform water ice directly into gas rather than a liquid phase.

    The warning sign can be found next door: Mars has a tenth of Earth’s mass and lost its atmosphere. Does Proxima b have an atmosphere? If so, the atmosphere and any surface ocean it sustains will moderate the temperature contrast between its permanent day and night sides. The James Webb Space Telescope, scheduled for launch in October 2018, will be able to distinguish between the temperature contrast expected if Proxima b is bare rock compared with the case where its climate is moderated by an atmosphere, possibly along with an ocean.

    A cosmic perspective about our origins would also contribute to a balanced worldview. The heavy elements that assembled to make Earth were produced in the heart of a nearby massive star that exploded. A speck of this material takes form as our body during our life but then goes back to Earth (with one exception, namely the ashes of Clyde Tombaugh, the discoverer of Pluto, which were put on the New Horizons spacecraft and are making their way back to space).

    What are we then, if not just a transient shape that a speck of material takes for a brief moment in cosmic history on the surface of one planet out of so many? Despite all of this, life is still the most precious phenomenon we treasure on Earth. It would be amazing if we find evidence for “life as we know it” on the surface of another planet, and even more remarkable if our telescopes will trace evidence for an advanced technology on an alien spacecraft roaming through interstellar space.

    References, some with links, some without links.

    Lingam, M. & Loeb, A. 2017, ApJ 837, L23-L28.

    Lingam, M. & Loeb, A. 2017, MNRAS (in the press); preprint available at https://arxiv.org/abs/1702.05500

    Lin, H., Gonzalez, G. A. & Loeb, A., 2014, ApJ 792, L7-L11.

    Loeb, A. & Turner, E. L. 2012, Astrobiology 12, 290-290.

    Guillochon, J. & Loeb, A. ApJ 811, L20-L26.

    Anglada-Escude’, G. et al. 2016, Nature 536, 437-440.

    Gillon, M. et al. 2016, Nature 542, 456-460.

    Lingam, M. & Loeb, A. 2017, PNAS (in the press); preprint available at https://arxiv.org/abs/1703.00878

    Loeb, A., Batista, R. A., & Sloan, D. 2016, JCAP 8, 40-52.

    Kreidberg, L. & Loeb, A. 2016, ApJ, 832, L12-L18.

    See the full article here .

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  • richardmitnick 2:27 pm on August 25, 2016 Permalink | Reply
    Tags: , , , , ESO Pale Red Dot Project,   

    From Don Lincoln via CNN: “A new planet in our neighborhood — how likely is life?” 

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    CNN

    August 24, 2016

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    Dr. Don Lincoln is a senior physicist at Fermilab and does research using the Large Hadron Collider. He has written numerous books and produces a series of science education videos. He is the author of Alien Universe: Extraterrestrial Life in Our Minds and in the Cosmos. Follow him on Facebook. The opinions expressed in this commentary are solely those of the author.

    Space. The final frontier.

    These words inspired many young people to enter science (including me), but I’ll bet that’s especially true for the team who announced Wednesday that they had found evidence of an Earth-like planet orbiting Proxima Centauri, our closest star. This planet is tentatively called Proxima b.

    Pale Red Dot
    Pale Red Dot project at ESO

    Scientists working at the European Southern Observatory (ESO), using the La Silla telescope, claim to have discovered the closest exoplanet to Earth.

    ESO 3.6m telescope & HARPS at LaSilla
    ESO 3.6m telescope & HARPS at LaSilla, Chile

    Exoplanet, of course, means planets orbiting stars other than the Sun. Over 3,000 exoplanets have been discovered by facilities like the ESO and the Kepler orbiting observatory. Most of them are huge planets orbiting very near their star — Jupiter-like planets heated to temperatures guaranteed to sterilize them of life as we know it.

    In recent years, instrumentation has improved to the point that not only can individual planets be found, but even complete solar systems, consisting of many planets. This has been a heady time for planet hunters.

    The goal of those inspired by Star Trek’s opening words has not been to find planets, but to find planets that are like Earth — meaning at a temperature on which liquid water could be present and which could theoretically support some form of life. This is what astronomers call “the habitable zone.” In addition, we’d like to find a planet that is nearby.

    After all, space is huge and human spacecraft using current technology would take tens of thousands of years to get to even this, our closest celestial neighbor. To give a sense of scale, that’s longer than human civilization has existed. There are plans under discussion that might reduce travel time to a more manageable duration, even less than a single human lifespan.

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    Related article: Proxima b: Closest rocky planet to our solar system found

    Centauris Alpha Beta Proxima 27, February 2012. Skatebiker
    Centauris Alpha Beta Proxima 27, February 2012. Skatebiker

    So what might this newly discovered planet look like? Well, even though its temperature is thought to be such that liquid water could exist, you shouldn’t imagine a lush and verdant world, with lovely blue waters, sandy beaches, lush and green plants, with an excited alien fish occasionally breaching the waters. There are lots of reasons why these are unreasonable expectations.

    Setting aside the possibility of life for a moment, Proxima Centauri is a red dwarf, which is the most common type of star in the galaxy. Red dwarfs are much smaller than our Sun. For instance, Proxima Centauri is only about 1.5 times larger than Jupiter. Red dwarfs are very dim. For instance, in the visible spectrum that we use to see, Proxima Centauri gives off 0.0056% as much as light as the Sun.

    Most of the light given off by Proxima Centauri is in the infrared region, but even if you compare all of the light emitted by Proxima Centauri in all wavelengths to the amount emitted by the Sun, Proxima Centauri still emits only 0.17% as much light as our own life-giving stellar companion. The star also emits as much x-rays as our own Sun, but Proxima b is much closer to its stellar parent, so the surface receives far more x-rays than Earth.

    In addition to being a very dim star, Proxima Centauri is known to be a “flare star,” which means the star periodically gives off far more light than usual. During these flares, the x-ray emission can go up tenfold.

    Because of the star’s small size, a planet in the habitable zone will have to be in a very small orbit, taking under two weeks to complete a single orbit. Any planet that close to a star will be “tidally locked,” which means that one face of the planet will constantly face the star. This is just like the Earth and Moon, where we see only one side of the Moon throughout the course of the Month. Proxima Centauri’s planetary companion will likely have one side in perpetual daylight, while the other is in perpetual night.

    So what about life? Are there any chances that an alien lizard might bask in Proxima Centauri’s light or try to find shade under an alien tree? Well, given the instability of the light emitted by the parent star, the answer is likely no, although the real answer to that question is obviously something for observations to answer.

    Given the very dim light output of the star, it is likely that any hypothetical plants would have to be black, as black is the most light-absorbent color. “Sunlight” would be precious and evolution would drive alien plants to find ways to collect every bit of energy that falls on them.

    Realistically, the prospect of life is improbable. This planet is unlikely to be a haven for people trying to escape the ecological issues of Earth, so we should not view this discovery as a way to ignore our own ecosystem.

    Still, the question of extraterrestrial life is a fascinating one, so astronomers are devising techniques to look at the planet’s atmosphere. Certain chemicals, like oxygen or methane, cannot exist long in a planet’s atmosphere without being constantly replenished by living organisms. Observing them would be strong evidence for life.

    So, what’s the bottom line? First, the discovery, if confirmed is extremely exciting. The existence of a nearby planet in the habitable zone will perhaps increase the interest in efforts like Project Starshot, which aims to send microprobes to Proxima Centauri with a transit time of about twenty years. It may well be that this discovery will excite an entirely new generation of the prospect “to boldly go where no one has gone before.”

    See the full article here .

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  • richardmitnick 1:16 pm on August 24, 2016 Permalink | Reply
    Tags: , ESO Pale Red Dot Project, ESOCast 87 video   

    From ESO: “ESOcast 87: Pale Red Dot Results” Video 

    ESO 50 Large

    European Southern Observatory

    Aug 24, 2016


    Watch, enjoy, learn.

    This is the ESOcast that no viewer will want to miss. We discuss the result of the quest to find a planet around the closest star to the Solar System.

    The Pale Red Dot campaign aimed to find a planet orbiting our nearest stellar neighbour, Proxima Centauri. Incredibly, the quest succeeded and the team did indeed find a planet. Even more excitingly, the planet, Proxima b, falls within the habitable zone of its host star. The newly discovered Proxima b is by far the closest potential abode for alien life.

    In this ESOcast, the results of this groundbreaking research are explained in detail, providing insights into the following points:

    • The extensive verification process the team went through to ensure this result was accurate.
    • The factors for and against the possibility of life on Proxima b.
    • The nature of a “habitable zone” around a star.

    The discovery of Proxima b is a major science result, making this ESOcast a must for those of you curious about one of the most intriguing questions in astronomy — “are we alone?”

    More information and download options: http://www.eso.org/public/videos/eso1…

    Subscribe to ESOcast in iTunes! https://itunes.apple.com/podcast/esoc…

    Receive future episodes on YouTube by pressing the Subscribe button above or follow us on Vimeo: https://vimeo.com/esoastronomy

    Watch more ESOcast episodes: http://www.eso.org/public/videos/arch…

    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”.

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  • richardmitnick 12:21 pm on February 16, 2016 Permalink | Reply
    Tags: , , ESO Pale Red Dot Project, Star's magnetic fields   

    From PALE RED DOT: “Cool Stars with a Magnetic Personality” 

    Pale Red Dot

    Pale Red Dot

    February 10, 2016
    Élodie Hébrard (York University)
    Rakesh Yadav (Harvard-Smithonian CfA).

    There is an invisible force active on the Sun which is due to its magnetic field. You may know that magnetic fields can be produced by electrical currents. The Sun’s plasma is a highly charged fluid. Due to the combined effect of large-scale ordered motions induced by the Sun’s rotation and the chaotic boiling of the plasma, there is an ample supply of electrical currents on the Sun to sustain the magnetic fields. This process of field generation by fluid motions is known as the Dynamo mechanism.

    Magnetic fields are responsible for producing very violent events called X-ray flares on the Sun. The energy which is stored in the magnetic field as tension gets released in the form of energetic electromagnetic radiation (ultra violet and X-rays). These flares also accelerate the plasma in the nearby region, which is ejected with very high velocities away from the Sun. These are known as Coronal Mass Ejections (CMEs).

    Solar eruption 2012 by NASA's Solar Dynamic Observatory SDO
    CME NASA Solar Dynamics Observatory [SDO]

    NASA SDO
    NASA SDO

    The energetic radiation and the CMEs form a dangerous partnership as they can gradually erode away the atmosphere (crucial for developing life) of a closely orbiting planet. You can learn more about X-ray flares in this short video.


    Download mp4 video here .

    Lets move away from our solar system and discuss the Pale Red Dot. Stars which are substantially cooler than the Sun are usually referred to as “red dwarfs” or “low-mass stars”. Proxima Centauri is one such star. But do not be fooled by their “coolness”! Astronomers have been looking at such stars for decades now—it turns out these stars are very active. In fact, they generate many more X-ray flares and CMEs than the Sun. Due to the high levels of violent events on these stars, the planets orbiting around them might encounter much more hostile environments than the planets in our own solar system. Such high activity is due to the presence of a magnetic field which is much stronger than what our Sun can produce. The high activity also makes it rather tricky to find Earth-like planets around these stars. Hey, wait a minute, how do we know that these stars have strong magnetic fields?

    The best way to measure the magnetic field of a star is to use the subtle effects it induces on the light it emits. Indeed, if a star has a magnetic field, its spectrum is affected: the different spectral lines split into several components, and each component has its own polarisation (it means that the magnetic field changes the vibrational properties of the light). This splitting effect is called the Zeeman effect. Measuring polarisation in spectral lines allows a reliable measurement of the stellar magnetic field, as explained in the short video below.


    Download mp4 video here .

    So now we know how we are able to measure a magnetic field, the next natural step is to reconstruct the map of the stellar magnetic field in order to know what it looks like: a dipolar field? a toroidal field?… To do that, we use the stellar rotation! More specifically, analysing the circular polarisation in spectral lines at different times as the star rotates, we get step by step a full 2D image of the magnetic field at the surface of the star. To carry out this exercise, astronomers use a method called Zeeman-Doppler Imaging (ZDI)—based on techniques developed for medical imaging! The following animations summarise the principles behind ZDI.

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    As the star rotates, an Earth-based observer sees the magnetic spot under different viewing angles, and moving at different projected velocities (upper panel). The level of circular polarisation measured in a spectral line evolves consequently (lower panel). The case of a radially oriented field (as depicted by the red arrows) is depicted here. Credit: J.-F. Donati.

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    Same as the previous figure, but here with the case of an azimuthally oriented field (as depicted by the red arrows) depicted. As opposed to the radial field situation the circular polarisation signature flips sign. This allows ZDI to disentangle between field orientations. Credit: J.-F. Donati.

    Dark starspots (similar to sunspots) are a visible consequence of the magnetic field activity of a star. As presented in Xavier Dumusque’s article, these spots induce distortions in the spectral line profiles (because of the Doppler effect), that induce radial velocity (RV) shift. Moreover, as the star rotates and the spot is carried across the visible disc, this distortion travels through the line profile (see figure below). Therefore, collecting data at different rotation phases allows us to unveil how the bright features are distributed on the stellar surface, exactly as for the magnetic field. In this case the method is simply called Doppler-Imaging.

    Instruments developed to gather simultaneously both the spectrum and its polarisation are called spectropolarimeters. The most used are ESPaDOnS atop the Mauna Kea in Hawaii, NARVAL atop the Pic-du-Midi in France, and HARPS-pol at La Silla observatory in Chile.

    CFHT ESPaDOns preferred
    ESPaDOnS

    ESO 3.6m telescope & HARPS at LaSilla
    ESO HARPS
    ESO HARPS

    CFHT
    ESO 3.6m telescope & HARPS at LaSilla
    Pic-du-midi Observatory France
    The telescopes hosting the three high-resolution spectropolarimeters designed for studies of stellar magnetic fields. Top Canada-France-Hawaii Telescope, Maunakea, Hawaii, USA; Middle ESO 3.6m Telescope, La Silla Observatory, Chile; Bottom Télescope Bernard Lyot, Pic-du-midi Observatory, France. Credits: J-C Cuillandre/E Hébrard/OMP.

    What can we do with these measurements? First, as stellar spots plague the planet detection from radial velocity measurements, we can use the map of the spot distribution to infer the induced RV. Although new, this method holds tremendous promise in being able to filter out the stellar signal, and thus to regain the power of diagnosing the potential presence of orbiting planets. Second, if our final goal is to detect a habitable Earth-like planet around cool stars, characterising the planetary environment is of prime importance. Indeed, the reduced temperatures of cool stars move their habitable zone closer in than around Sun-like stars. Earth-like planets orbiting such stars would experience a stronger stellar magnetic pressure, exposing the planet’s atmosphere to erosion by the stellar wind and CMEs. Therefore there is an interest for estimating the stellar magnetic environment surrounding these planets. From the reconstruction of large-scale magnetic field topologies with ZDI, one can extrapolate the field outwards (see V374 Peg figure below) and ultimately it will allow a more thorough characterisation of detected planets, and a better assessment of the suitability of a planet for hosting life. Finally, the observed large-scale magnetic properties can be useful to better understand the stellar interior and the magnetic field generation.

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    Magnetic field lines of the active red dwarf V374 Peg, extending in space above the surface of the star. The surface magnetic field has been mapped with ZDI, serving as a basis for the extrapolation to the whole magnetosphere. The simple dipole, magnet-like structure of the field is very obvious. Field lines forming loops above the surface are shown in white, while field lines open to the interstellar medium are shown in blue. Credit: MM Jardine & J-F Donati.

    So far we have discussed what we know about red dwarf stars observationally. Let’s go into some details about the latest theoretical models which try to explain why these stars have such strong magnetic fields. We will now discuss a recent supercomputer simulation which tried to mimic what happens in red dwarf stars.

    In computer simulations a star is considered to be a perfect sphere of hot plasma which rotates around an axis. To model the plasma flows, we assume that it follows the Navier-Stokes equation—which basically tells us that the change in the momentum of a tiny fluid packet is proportional to the sum of various forces acting on it. The behaviour of the magnetic field is governed by Maxwell’s equations (under the so-called MHD approximation). Furthermore, there are other equations of importance which describe the energy conservation and the thermodynamical state of the fluid (temperature, pressure, etc). These equations are then solved using sophisticated numerical algorithms (codes with 10s of thousands of lines) which are run on some of the world’s largest supercomputers.

    HYDRA supercomputer at the Max Planck Computing and Data Facility in Garching bei München, Germany
    The HYDRA supercomputer at the Max Planck Computing and Data Facility in Garching bei München, Germany. In total there are ~83,000 cores with a main memory of 280 TB and a peak performance of about 1.7 PetaFlop/s. Credit: Max Planck Society.

    If we model conditions, which are similar to those found in red dwarf stars, the simulation produces many properties similar to what we actually observe. The magnetic field resulting from this simulation is depicted in the figure below. The field lines are coming out of the visible north pole of the “star”. This is due to a large region of magnetic field with one polarity (shown with yellow shades). A similar behaviour occurs in the south pole which is not visible in the image. Along with large regions with similar polarity, there are smaller regions containing both polarities of the magnetic field (close-by yellow and blue shades), scattered almost all over the surface. These “bipolar” regions are necessary to generate twisted and stretched field lines which lead to X-ray flares and CMEs. In fact, the bipolar “active” regions on this “star” are much more numerous than what we see on the Sun. By extension, this model then predicts that the red dwarf stars should generate many more X-ray flares. The strength of the magnetic field in the image is also typically about several kiloGauss, at least ten times stronger than the Sun’s typical magnetic field.

    Numerical simulation aimed at studying magnetic field generation in a red dwarf star
    Numerical simulation aimed at studying magnetic field generation in a red dwarf star. The two magnetic polarities are depicted in yellow and blue. The cyan-color pipe shows the rotation axis. Credit: Rakesh Yadav.

    To sum up, this “star in a computer” is able to self-consistently produce a very strong magnetic field and predicts that these stars should be much more active than the Sun. We have made some progress in the sense that this simulated star satisfies some observational constraints. The next step is to use the predictions from this simulation and test them using more detailed observations. The Pale Red Dot project is one such step.

    About the authors

    Élodie Hébrard graduated her PhD in astrophysics in 2015 at the Institut de Recherches en Astrophysique et Planétologie of the University of Toulouse (France). She studies the use of the Zeeman-Doppler Imaging technique to characterise stellar activity and magnetic fields, ultimately designing new approaches to filter out the activity-induced radial velocity signals that mimic those due to planets. Élodie is now a postdoctoral fellow at the Department of Physics and Astronomy of the University of York (Canada).

    Rakesh Yadav is a theoretical astrophysicist who uses supercomputers to understand how planets and stars produce their magnetic fields. He finished his BSc and MSc (physics) in 2011 at the Indian Institute of Technology Kanpur, India. He moved to Germany in 2012 to pursue a PhD in computational astrophysics at the Max Planck Institut für Sonnensystemforschung and the University of Göttingen. After finishing his PhD in 2015 he joined the Harvard-Smithsonian Center for Astrophysics as a Post Doctoral scientist.

    See the full article here.

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    What is PALE RED DOT?

    It is an outreach project to show to the public how scientists are working to address a major question that could affect us all, namely are there Earth-like planets around the nearest stars?

    Why we call it PALE RED DOT?

    In 1990, Voyager 1, on its trek towards interstellar space, sent back a picture of the Inner Solar System on which the Earth occupied less than a pixel. This image of Earth was called Pale Blue Dot, and inspired the late Carl Sagan’s essay ‘Pale Blue Dot : A vision of the human future in Space’, which in turn has been the source of inspiration for a generation of exoplanet hunters. Given that Proxima Centauri — or just Proxima — is a red dwarf star, such a planet would show reddish tints. Even if successful, we will only obtain information about its orbital period and mass — even less than Voyager 1’s pale blue pixel… at least for now!

    What is special about the project?

    Proxima Centauri is the nearest star to the Sun. The discovery of a planet with some characteristics like Earth in our immediate vicinity would be momentous. After years of data acquisition by many researchers and teams, a signal has been identified which may indicate the presence of an Earth-like planet. The Pale Red Dot project will carry out further detailed observations with the aim to confirm or refute the presence of the planet. By broadcasting the progress and results of the observations through all media channels available e.g. press, website, and social media, the Pale Red Dot project aims to promote Science Technology Engineering and Mathematics (STEM) in the broader society, inform the public and hopefully inspire a new generation of scientists.

    How such a scientific program is organized?

    The planned observation campaign is based on a proposal submitted by the involved scientists to ESO, LCOGT and BOOTES observatories. The proposals, in turn, are based on the analysis of data accumulated and obtained over the years by ourselves or by other researchers abroad. Observatories and other advanced research facilities are mostly supported by public resources, large international consortia and private foundations.

    How the results will be reported?

    As in any professional scientific work, final results need to be reviewed by the community before being announced. After the campaign is finished by April 1st, the really tough process of analyzing the data, drawing conclusions and presenting them in a credible manner will begin. After that, the analysis will be summarized in an article and submitted to a scientific journal. At that point, one or more scientists NOT involved in the project will critically revise the work, suggest modifications and even reject its publication if fundamental flaws are spotted. This last step of peer-review can take any time between a few months to a year or two. Hopefully, the data will prove to be high quality and the observations will have a straightforward interpretation, but that is just a hope. A few key milestones of the peer-review process will also be reported on the website, which might remain active at a lower activity level after the observing campaign has finished.

     
  • richardmitnick 9:36 am on February 9, 2016 Permalink | Reply
    Tags: , , ESO Pale Red Dot Project,   

    From PALE RED DOT: “Living in Twilight: An Overview of our Closest and Smallest Stellar Neighbors” 

    Pale Red Dot

    Pale Red Dot

    February 2, 2016
    Sergio Dieterich, Carnegie Institution for Science

    When members of our research group go observing at [NOAO] Cerro Tololo Inter-American Observatory in the Chilean Andes we spend most of our time in a cozy heated control room.

    CTIO large
    NOAO CTIO

    Modern astronomical observing is done mostly by monitoring computer screens and entering commands to tell the telescope where to point next. If we have to put on our winter jackets and climb the flight of stairs to where the telescope is—under the open dome—it is because something went wrong and we are frantically trying to fix the problem and minimize the loss of precious telescope time. There is one exception. Our group’s tradition dictates that when we are training a new student, and the season and time of night is just right, we will go up to the dome and have our new colleague look through the telescope’s eyepiece. Photography does not do justice to the sight that emerges: a bright ruby red speck of light floats seemingly in front of a vast ocean of fainter and whiter stars. That red speck is Proxima Centauri, the closest star to us other than the Sun, the subject of the Pale Red Dot project, and a typical low mass star. Stars like Proxima Centauri, or just Proxima for short, are amongst the smallest but also the most common types of stars in the Galaxy. Let’s take a few minutes to understand our smallest and closest stellar neighbors a little better.

    Imagine for a moment that we drop a large ceramic dinner plate on a hard kitchen floor. The plate shatters into many, many, pieces, of all different sizes. We then look down and examine the results of our carelessness. Our attention is first drawn to the handful of large fragments. After a more careful look we see that for every one of those large ceramic fragments there are dozens, if not hundreds, of much smaller pieces. Further, we soon realize that if we have any hope of reconstructing the original plate or figuring out what happened we cannot simply ignore those smaller pieces and sweep them under the rug. This unfortunate kitchen accident is a rough analogy to the stellar formation process, and it sheds some light on how the Milky Way Galaxy ended up with the stellar population we observe today. Stars are formed when clouds of interstellar gas and dust, called giant molecular clouds, are somehow perturbed—causing the cloud to start collapsing under its own gravitational pull. Several points in the collapsing cloud achieve higher and higher density, and therefore exert an even greater gravitational force. Over the course of hundreds of thousands of years these high density regions consume enough gas and become compact enough to form stellar embryos, or protostars. When the protostar’s core becomes hot enough to ignite and sustain nuclear fusion, a star is born. In a manner similar to what happens with our shattering plate, but for different physical reasons, the result of this cloud collapse mechanism heavily favors the production of stars whose masses are anywhere from about 60% to about only 8% of our Sun’s mass. When fully formed and contracted these are tiny stars, with the majority having radii between 20% and only 10% our Sun’s radius. The smallest are very close in size (but not in mass or density!) to the planet Jupiter. What these small stars lack in terms of size they make up for in their sheer numbers. Indeed, out of the 366 stars whose accurately measured distances place them within 32.6 light-years (or 10 parsecs, in astronomical lingo) of our Solar System, 275 belong to this type. These objects are commonly known as red dwarfs, or M dwarfs, in the stellar classification system used by professional astronomers. Using the fair assumption that our solar neighborhood is typical of much of the Milky Way Galaxy, that means that about 75% of the stars in our galaxy are M dwarfs. The M dwarf class is sometimes subdivided, with stars having about 20% or less the mass of our Sun being called Very Low Mass, or VLM stars. Proxima is in the upper mass range of the VLM stars.

    What are red dwarfs like as stars, and how does their energy output compare to our Sun’s? These stars are incredibly faint, and not even Proxima can be seen with the naked eye despite its proximity of only 4.25 light-years. To put this distance in context, the best estimates for the diameter of the Milky Way Galaxy place it at anywhere between 100,000 to 180,000 light-years; if our galaxy were a city 10 km across Proxima would be so close to us as to be knocking on our front door! And yet stars that are intrinsically more luminous can be seen with the naked eye from distances almost one fifth of the way across the galaxy. If a representative sample of red dwarfs were all placed at the same distance to us as the Sun the brightest ones would shine only about 7 percent as bright as the Sun. Recent research by our group indicates that the faintest of the VLM stars would shine with only about 0.016 percent, or about 1/6,000th , the brightness of our Sun. Proxima has a total energy output about 0.2% that of our Sun.

    Red dwarfs are not only faint, but the little light they do emit is also very different from the warm sunlight we enjoy on a Caribbean beach on Earth. The surface of our Sun shines at a temperature of approximately 5,500 degrees Celsius (10,000 F). At that temperature most of the light is emitted in the yellow-green region of the visible light spectrum. It therefore makes sense that the human eye has evolved to be the most sensitive to the yellow-green light that most strongly bathes our planet. Low mass stars have significantly cooler surface temperatures: about 3,500 C (6,400 F) for the hottest red dwarfs and approximately 1,800 C (3,300 F) for the smallest and faintest VLM stars. At these temperatures not only does the star emit considerably less light overall, but the light emitted is also shifted to longer wavelengths, which we perceive as redder colors. The color spectrum of the hottest red dwarfs has its peak at a deep red color that is just at the limit of the detection range of the human eye. For the faintest VLM stars the color spectrum peaks in the near infrared range of the electromagnetic spectrum, well beyond the detection capabilities of the human eye. In both cases the human eye’s enhanced sensitivity to yellow-green light will shift the perceived colors to shorter wavelengths than the peak color emission. A future interstellar voyager who sees a hot red dwarf up close will likely perceive a distinctive orange hue, whereas one of the cooler red dwarfs may appear to be a lively red (Figure 2ab). To make these faintest of faint stars even more unusual, there is evidence to suggest that they have strong surface magnetic fields. These magnetic fields would cause dark spots analogous to sunspots, but they may be more numerous and larger—perhaps covering a substantial portion of the star’s surface.

    2cc73-reddwarfstar
    2cc73 Red Dwarf

    Astronomers currently think that as many as 1/3 of red dwarfs may harbor rocky planets with compositions similar to Earth’s. Could life evolve on these planets, and what would life around a red dwarf be like? The idea of life evolving on planets around red dwarfs is extremely exciting. If for no other reason, their sheer numbers means that the question of red dwarf habitability has tremendous implications in determining whether we live in a Universe teeming with life or whether life is a sparse occurrence. Despite this huge potential, the notion of life on low mass star systems is not without its challenges.

    Because of their lower mass and consequentially weaker gravitational pull, red dwarfs take a very long time to settle into their fully contracted configuration, once they stop accreting material from their parent star forming cloud. Similarly, the comparatively slow rate of nuclear reactions in a low mass star’s core causes these stars to have extremely long lives when compared to more massive stars. Their slow evolution and long lives are both a blessing and a curse for the possibility of life. Once fully formed and contracted, red dwarfs change very little for hundreds of billions of years. The oldest red dwarfs may therefore have provided a stable environment for life for as long as they have existed, roughly 10 billion years based on current estimates for the age of the Galaxy. Compare that with only 4.1 billion years of biological evolution on Earth. Even if evolution around a planet hosting red dwarf happened slower and hit a few dead ends, the final result might still mean a complex and diverse ecosystem. However, the prospect of a prolonged period of stability suitable for biological evolution is only exciting if we assume that the right conditions for life were present to begin with, and that is where a red dwarf’s life in the slow lane becomes a problem. Liquid water is essential for life as we know it on Earth, and liquid water can only exist if the temperature on a planet’s surface allows it. A planet’s temperature is governed primarily by the planet’s orbital distance from its parent star and the star’s intrinsic luminosity. Astronomers call the range of orbital radii allowing the existence of liquid water the ‘habitable zone’ around a star. All stars are significantly brighter during their initial contraction phase, when most of the star’s energy comes from its gravitational collapse and not from nuclear fusion. For red dwarfs this initial period of increased luminosity may last up to 3 billion years, which is well beyond the formation time for planets. Any planet that forms in what will eventually become the star’s habitable zone will be subject to scorching heat during its early life. Calculations suggest that this fiery youth may cause all water to evaporate away, thus effectively sterilizing the planet. A possible way out of this scenario involves the retention of water in minerals called chondrites. If chondrites are present in sufficient amounts in the rocky material that coalesces to form planets, the fully formed planets could have substantial water reserves in their interiors. The water could then be released from the planet’s interior by volcanic activity at later times when the surface temperature is right for liquid water. Whether or not this scenario is likely is an area of active research.

    Another interesting aspect of the idea of life in planets orbiting red dwarfs has to do with the extreme proximity of the star’s habitable zone to the star itself. These stars are so faint that planets in their habitable zones would have orbits smaller than the orbit of Mercury in our Solar System. At such small distances the slight difference in the star’s gravitational pull from the planet’s side facing the star to the planet’s far side causes a phenomenon called tidal locking. In a tidally locked planet the same side of the planet always faces the star, causing it to be much hotter than the side that is perpetually facing away from the star. The Earth-Moon system is a good example of a tidally locked satellite. The habitable conditions in a tidally locked planet may be confined to a narrow ring shaped region where the illuminated side meets the dark side of the planet. This habitable region would be in perpetual twilight, with the star shining low in the horizon. Such low illumination conditions may seem rather depressing to us humans, but low light levels peaking at redder wavelengths are the norm around red dwarfs, and it is quite possible that any existing life form in these otherworldly environments may have evolved to use infrared light in much the same way we utilize the bright yellow-green light of our parent star. Perhaps venturing too close to the planet’s illuminated side would cause these creatures to get a “star burn” from red light in much the same way we get can get a sunburn from the small portion of our Sun’s energy that is emitted as ultraviolet light.

    Finally, a treatment of low mass stars would not be complete without making a connection to their lower mass cousins, the substellar brown dwarfs.

    Brown dwarf
    Artist’s concept of a T-type brown dwarf

    Looking back to our shattered plate analogy of star formation, the cloud collapse process that produces stars with a wide range of different masses can also produce objects whose mass is too small to create the conditions necessary for sustainable core nuclear fusion. These objects are called brown dwarfs. Brown dwarfs look much like their VLM star counterparts in their youth because during that phase gravitational contraction releases a large amount of energy for both stars and brown dwarfs. However, once brown dwarfs are fully contracted they keep cooling down over the course of billions of years. For much of the red dwarf range of temperatures and colors it is difficult to tell whether a given object is a young brown dwarf or a VLM star of any age. Recent research by my collaborators and I indicates that the stellar sequence comes to an end when we reach objects with surface temperatures of about 1,800 C (3,300 F) and luminosities of roughly 1/6,000th that of our Sun (interested in the technical details? read the paper here). We came to this conclusion by performing the observations necessary to estimate the radius of a sample of 63 objects thought to lie close to the end of the stellar sequence. We then noted that for temperatures higher than 1,800 C the objects cover a wide range of radii, including the radii expected for old and fully contracted stars. At cooler temperatures we encountered larger radii that can only be explained if the objects in question are young brown dwarfs that are not yet fully contracted.

    The temperature we obtained for the end of the stellar sequence is substantially higher than that predicted by theoretical models, and we are now trying to pinpoint the root causes of this discrepancy. As a part of this research we have found what we believe to be the smallest known star to date and also a representative of the smallest possible stars. This star is called 2MASS J0523-1403, and shines faintly in the constellation Lepus the hare, under the feet of Orion the hunter. 2MASS J0523-1403 has a radius of only [?] percent the radius of our Sun. That radius makes 2MASS J0523-1403 about 15 percent smaller than the planet Jupiter. Indeed, perhaps coincidentally, the size we calculate for 2MASS J05234-1403 is within 1 percent of the size of the planet Saturn. Therefore while we can say that VLM stars in general have sizes comparable to Jupiter, we can go one step further and say that the smallest stars are Saturn sized. In making these comparisons we must be careful not to confuse volume and mass. While these stars have the volume of giant planets their mass is theoretically predicted to be anywhere from 70 to 80 times the mass of Jupiter, making them incredibly dense. In fact, it is the quantum mechanical limit on the allowed upper density that causes brown dwarfs to stop contracting before nuclear fusion ignites.

    Over the last few decades our knowledge of red dwarfs has gone from simply knowing that they exist, to realizing just how numerous they are, and finally to being able to characterize them and assess their suitability as hosts for habitable planets. This progress is in part due to advances in observational astronomy, such as the substitution of blue sensitive photographic film to red sensitive digital CCD detectors and infrared detectors. Those advances in sensitivity and data management were then utilized to conduct large all-sky surveys that revealed a multitude of new red dwarfs and gave astronomers the unprecedented ability to study them not only as individual objects but also as a population. We now have a good understanding of how red dwarfs contribute to the overall stellar population of the Galaxy and are gaining greater understanding of their promises and challenges as hosts of livable planets. The history of astronomy has taught us that we cannot predict what the next discovery will be and how it will change our understanding of things. It could well be that after thorough study we may realize that the roughly 75 percent of the stars in the Galaxy that we call red dwarfs are not suitable as hosts of living planets. That alone would let us know that life in the Universe might be a bit more special than previously thought and how fortunate we are to have a home on planet Earth. On the opposing view, we know from our experience on Earth that evolution usually finds a way to make life flourish in the most extreme and odd environments. If life forming mechanisms are able to overcome the challenges we discussed here, plus many others that we have not yet even imagined, it is quite possible that our solar neighborhood abounds with beings of unimaginable forms thriving under the soft red twilight of their tiny parent star.

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    What is PALE RED DOT?

    It is an outreach project to show to the public how scientists are working to address a major question that could affect us all, namely are there Earth-like planets around the nearest stars?

    Why we call it PALE RED DOT?

    In 1990, Voyager 1, on its trek towards interstellar space, sent back a picture of the Inner Solar System on which the Earth occupied less than a pixel. This image of Earth was called Pale Blue Dot, and inspired the late Carl Sagan’s essay ‘Pale Blue Dot : A vision of the human future in Space’, which in turn has been the source of inspiration for a generation of exoplanet hunters. Given that Proxima Centauri — or just Proxima — is a red dwarf star, such a planet would show reddish tints. Even if successful, we will only obtain information about its orbital period and mass — even less than Voyager 1’s pale blue pixel… at least for now!

    What is special about the project?

    Proxima Centauri is the nearest star to the Sun. The discovery of a planet with some characteristics like Earth in our immediate vicinity would be momentous. After years of data acquisition by many researchers and teams, a signal has been identified which may indicate the presence of an Earth-like planet. The Pale Red Dot project will carry out further detailed observations with the aim to confirm or refute the presence of the planet. By broadcasting the progress and results of the observations through all media channels available e.g. press, website, and social media, the Pale Red Dot project aims to promote Science Technology Engineering and Mathematics (STEM) in the broader society, inform the public and hopefully inspire a new generation of scientists.

    How such a scientific program is organized?

    The planned observation campaign is based on a proposal submitted by the involved scientists to ESO, LCOGT and BOOTES observatories. The proposals, in turn, are based on the analysis of data accumulated and obtained over the years by ourselves or by other researchers abroad. Observatories and other advanced research facilities are mostly supported by public resources, large international consortia and private foundations.

    How the results will be reported?

    As in any professional scientific work, final results need to be reviewed by the community before being announced. After the campaign is finished by April 1st, the really tough process of analyzing the data, drawing conclusions and presenting them in a credible manner will begin. After that, the analysis will be summarized in an article and submitted to a scientific journal. At that point, one or more scientists NOT involved in the project will critically revise the work, suggest modifications and even reject its publication if fundamental flaws are spotted. This last step of peer-review can take any time between a few months to a year or two. Hopefully, the data will prove to be high quality and the observations will have a straightforward interpretation, but that is just a hope. A few key milestones of the peer-review process will also be reported on the website, which might remain active at a lower activity level after the observing campaign has finished.

     
  • richardmitnick 2:44 pm on January 16, 2016 Permalink | Reply
    Tags: , , ESO Pale Red Dot Project,   

    From ESO: ESOCast 80 Pale Red Dot – Follow a Live Planet Hunt 


    European Southern Observatory

    Published on Jan 15, 2016

    A unique new project will now allow members of the public to go behind the scenes and follow a planet hunt as it happens!

    Pale Red Dot planet search

    Temp 1

    Pale Red Dot is an international search for an Earth-like exoplanet around the closest star to us, Proxima Centauri. It will use HARPS, attached to ESO’s 3.6-metre telescope at La Silla Observatory, as well as the Las Cumbres Observatory Global Telescope Network (LCOGT) and the Burst Optical Observer and Transient Exploring System (BOOTES).

    ESO HARPS
    ESO 3.6m telescope & HARPS at LaSilla
    ESO Harps

    ESO 3.6 Meter Telescpe
    ESO 3.6 meter telescope interior
    3.6 meter telescope at La Silla

    LCOGT Las Cumbres Observatory Global Telescope Network
    Las Cumbres Observatory Global Telescope Network (LCOGT)

    BOOTES1
    BOOTES2
    BOOTES3
    BOOTES

    It will be one of the few outreach campaigns allowing the general public to witness the scientific process of data acquisition in modern observatories. The public will see how teams of astronomers with different specialities work together to collect, analyse and interpret data, which may or may not be able to confirm the presence of an Earth-like planet orbiting our nearest neighbour . The outreach campaign consists of blog posts and social media updates on the Pale Red Dot Twitter account and using the hashtag #PaleRedDot. For more information visit the Pale Red Dot website: http://www.palereddot.org

    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
    LaSilla

    ESO VLT Interferometer
    VLT

    ESO Vista Telescope
    VISTA

    ESO NTT
    NTT

    ESO VLT Survey telescope
    VLT Survey Telescope

    ALMA Array
    ALMA

    ESO E-ELT
    E-ELT

    ESO APEX
    Atacama Pathfinder Experiment (APEX) Telescope

     
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