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  • richardmitnick 2:09 pm on May 4, 2015 Permalink | Reply
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    From ESO: “A Hole in the Sky” 


    European Southern Observatory

    4 May 2015
    No Writer Credit

    1

    Rather than showing spectacular objects, some of the most surprising images of the Universe instead focus on emptiness. This new image from the 2.2-metre MPG/ESO telescope shows dark tentacles swirling outwards from a dark, blank spot of space in the centre of the frame, particularly conspicuous against the dense peppering of bright gold and red stars across the rest of the image.

    ESO 2.2 meter telescope
    ESO 2.2 meter telescope interior
    2.2-metre MPG/ESO telescope

    ESO WFI LaSilla
    WFI

    This region is not a hole in the cosmos, or an empty patch of sky. The dark lanes are actually made up of thick, opaque dust lying between us and the packed star field behind it. This obscuring dust forms part of a dark molecular cloud, cold and dense areas where large quantities of dust and molecular gas mingle and block the visible light emitted by more distant stars.

    It is still unclear how these clouds form, but they are thought to be the very early stages of new star formation — in the future, the subject of this image may well collapse inwards on itself to form a new star system.

    Although the cloud in this image is a fairly anonymous resident of the nearby Universe — catalogued as LDN1774 — one of the most famous examples of a molecular cloud is the very similar Barnard 68, which lies some 500 light-years away from us.

    2
    This image shows a colour composite of visible and near-infrared images of the dark cloud Barnard 68 . It was obtained with the 8.2-m VLT ANTU telescope and the multimode FORS1 instrument in March 1999. At these wavelengths, the small cloud is completely opaque because of the obscuring effect of dust particles in its interior.

    ESO VLT
    VLT

    ESO FORS1
    FORS

    Barnard 68 has been observed extensively using ESO telescopes, both in visible (eso9924a) and infrared light (eso9934, eso0102a). As shown in these different images, it is possible to probe through dark cosmic dust using infrared light, but visible-light observations such as those shown in this VLT image cannot see beyond the smokescreen.

    This image was taken by the Wide Field Imager, an instrument mounted on ESO’s 2.2-metre MPG/ESO telescope at La Silla, Chile.

    See the full article http://www.eso.org/public/images/potw1518a/.

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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 6:29 am on April 22, 2015 Permalink | Reply
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    From ESO: “First Exoplanet Visible Light Spectrum” 


    European Southern Observatory

    22 April 2015
    Jorge Martins
    Instituto de Astrofísica e Ciências do Espaço/Universidade do Porto
    Porto, Portugal
    Tel: +56 2 2463 3087
    Email: Jorge.Martins@iastro.pt

    Nuno Santos
    Instituto de Astrofísica e Ciências do Espaço/Universidade do Porto
    Porto, Portugal
    Tel: +351 226 089 893
    Email: Nuno.Santos@iastro.pt

    Stéphane Udry
    Observatoire de l’Université de Genève
    Geneva, Switzerland
    Tel: +41 22 379 24 67
    Email: stephane.udry@unige.ch

    Isabelle Boisse
    Aix Marseille Université
    Marseille, France
    Email: Isabelle.Boisse@lam.fr

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

    Temp 1

    Astronomers using the HARPS planet-hunting machine at ESO’s La Silla Observatory in Chile have made the first-ever direct detection of the spectrum of visible light reflected off an exoplanet. These observations also revealed new properties of this famous object, the first exoplanet ever discovered around a normal star: 51 Pegasi b. The result promises an exciting future for this technique, particularly with the advent of next generation instruments, such as ESPRESSO, on the VLT, and future telescopes, such as the E-ELT.

    The exoplanet 51 Pegasi b [1] lies some 50 light-years from Earth in the constellation of Pegasus. It was discovered in 1995 and will forever be remembered as the first confirmed exoplanet to be found orbiting an ordinary star like the Sun [2]. It is also regarded as the archetypal hot Jupiter — a class of planets now known to be relatively commonplace, which are similar in size and mass to Jupiter, but orbit much closer to their parent stars.

    Since that landmark discovery, more than 1900 exoplanets in 1200 planetary systems have been confirmed, but, in the year of the twentieth anniversary of its discovery, 51 Pegasi b returns to the ring once more to provide another advance in exoplanet studies.

    The team that made this new detection was led by Jorge Martins from the Instituto de Astrofísica e Ciências do Espaço (IA) and the Universidade do Porto, Portugal, who is currently a PhD student at ESO in Chile. They used the HARPS instrument on the ESO 3.6-metre telescope at the La Silla Observatory in Chile.

    ESO HARPS
    HARPS

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

    ESO LaSilla Long View
    LaSilla

    Currently, the most widely used method to examine an exoplanet’s atmosphere is to observe the host star’s spectrum as it is filtered through the planet’s atmosphere during transit — a technique known as transmission spectroscopy. An alternative approach is to observe the system when the star passes in front of the planet, which primarily provides information about the exoplanet’s temperature.

    The new technique does not depend on finding a planetary transit, and so can potentially be used to study many more exoplanets. It allows the planetary spectrum to be directly detected in visible light, which means that different characteristics of the planet that are inaccessible to other techniques can be inferred.

    The host star’s spectrum is used as a template to guide a search for a similar signature of light that is expected to be reflected off the planet as it describes its orbit. This is an exceedingly difficult task as planets are incredibly dim in comparison to their dazzling parent stars.

    The signal from the planet is also easily swamped by other tiny effects and sources of noise [3]. In the face of such adversity, the success of the technique when applied to the HARPS data collected on 51 Pegasi b provides an extremely valuable proof of concept.

    Jorge Martins explains: “This type of detection technique is of great scientific importance, as it allows us to measure the planet’s real mass and orbital inclination, which is essential to more fully understand the system. It also allows us to estimate the planet’s reflectivity, or albedo, which can be used to infer the composition of both the planet’s surface and atmosphere.”

    51 Pegasi b was found to have a mass about half that of Jupiter’s and an orbit with an inclination of about nine degrees to the direction to the Earth [4]. The planet also seems to be larger than Jupiter in diameter and to be highly reflective. These are typical properties for a hot Jupiter that is very close to its parent star and exposed to intense starlight.

    HARPS was essential to the team’s work, but the fact that the result was obtained using the ESO 3.6-metre telescope, which has a limited range of application with this technique, is exciting news for astronomers. Existing equipment like this will be surpassed by much more advanced instruments on larger telescopes, such as ESO’s Very Large Telescope and the future European Extremely Large Telescope [5].

    ESO VLT
    VLT

    ESO E-ELT
    E-ELT

    “We are now eagerly awaiting first light of the ESPRESSO spectrograph on the VLT so that we can do more detailed studies of this and other planetary systems,” concludes Nuno Santos, of the IA and Universidade do Porto, who is a co-author of the new paper.

    ESO Espresso
    Espresso instrument of the future

    Notes

    [1] Both 51 Pegasi b and its host star 51 Pegasi are among the objects available for public naming in the IAU’s NameExoWorlds contest.

    [2] Two earlier planetary objects were detected orbiting in the extreme environment of a pulsar.

    [3] The challenge is similar to trying to study the faint glimmer reflected off a tiny insect flying around a distant and brilliant light.

    [4] This means that the planet’s orbit is close to being edge on as seen from Earth, although this is not close enough for transits to take place.

    [5] ESPRESSO on the VLT, and later even more powerful instruments on much larger telescopes such as the E-ELT, will allow for a significant increase in precision and collecting power, aiding the detection of smaller exoplanets, while providing an increase in detail in the data for planets similar to 51 Pegasi b.
    More information

    This research was presented in a paper “Evidence for a spectroscopic direct detection of reflected light from 51 Peg b”, by J. Martins et al., to appear in the journal Astronomy & Astrophysics on 22 April 2015.

    The team is composed of J. H. C. Martins (IA and Universidade do Porto, Porto, Portugal; ESO, Santiago, Chile), N. C. Santos (IA and Universidade do Porto), P. Figueira (IA and Universidade do Porto), J. P. Faria (IA and Universidade do Porto), M. Montalto (IA and Universidade do Porto), I. Boisse (Aix Marseille Université, Marseille, France), D. Ehrenreich (Observatoire de Genève, Geneva, Switzerland), C. Lovis (Observatoire de Genève), M. Mayor (Observatoire de Genève), C. Melo (ESO, Santiago, Chile), F. Pepe (Observatoire de Genève), S. G. Sousa (IA and Universidade do Porto), S. Udry (Observatoire de Genève) and D. Cunha (IA and Universidade do Porto).

    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 7:23 pm on January 25, 2015 Permalink | Reply
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    From ESO: All the Telescopes at LaSilla Annotated. Nice shot 


    European Southern Observatory

    1
    This image places La Silla beneath a clear blue sky along the horizon of the Atacama Desert. Annotations identify the individual telescopes, of which three three were built and are operated by the ESO. Several telescopes are located at the site and are partly maintained by ESO, making it one of the largest observatories in the Southern Hemisphere.

    Credit: ESO/José Francisco Salgado (josefrancisco.org)

    See the full article here.

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  • richardmitnick 7:34 am on January 7, 2015 Permalink | Reply
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    From ESO: “Where Did All the Stars Go?” 


    European Southern Observatory

    7 January 2015
    Richard Hook
    ESO education and Public Outreach Department
    Garching bei München, Germany

    Tel: +49 89 3200 6655
    Email: rhook@eso.org

    Some of the stars appear to be missing in this intriguing new ESO image. But the black gap in this glitteringly beautiful starfield is not really a gap, but rather a region of space clogged with gas and dust. This dark cloud is called LDN 483 — for Lynds Dark Nebula 483. Such clouds are the birthplaces of future stars. The Wide Field Imager, an instrument mounted on the MPG/ESO 2.2-metre telescope at ESO’s La Silla Observatory in Chile, captured this image of LDN 483 and its surroundings.

    ESO Wide Field Imager 2.2m LaSilla
    WFI

    ESO MPG 2.2 meter telescope
    MPG/ESO 2.2-metre telescope

    ESO LaSilla Long View
    ESO LaSilla

    l

    LDN 483 [1] is located about 700 light-years away in the constellation of Serpens (The Serpent). The cloud contains enough dusty material to completely block the visible light from background stars. Particularly dense molecular clouds, like LDN 483, qualify as dark nebulae because of this obscuring property. The starless nature of LDN 483 and its ilk would suggest that they are sites where stars cannot take root and grow. But in fact the opposite is true: dark nebulae offer the most fertile environments for eventual star formation.

    Astronomers studying star formation in LDN 483 have discovered some of the youngest observable kinds of baby stars buried in LDN 483’s shrouded interior. These gestating stars can be thought of as still being in the womb, having not yet been born as complete, albeit immature, stars.

    In this first stage of stellar development, the star-to-be is just a ball of gas and dust contracting under the force of gravity within the surrounding molecular cloud. The protostar is still quite cool — about –250 degrees Celsius — and shines only in long-wavelength submillimetre light [2]. Yet temperature and pressure are beginning to increase in the fledgling star’s core.

    This earliest period of star growth lasts a mere thousands of years, an astonishingly short amount of time in astronomical terms, given that stars typically live for millions or billions of years. In the following stages, over the course of several million years, the protostar will grow warmer and denser. Its emission will increase in energy along the way, graduating from mainly cold, far-infrared light to near-infrared and finally to visible light. The once-dim protostar will have then become a fully luminous star.

    As more and more stars emerge from the inky depths of LDN 483, the dark nebula will disperse further and lose its opacity. The missing background stars that are currently hidden will then come into view — but only after the passage of millions of years, and they will be outshone by the bright young-born stars in the cloud [3].
    Notes

    [1] The Lynds Dark Nebula catalogue was compiled by the American astronomer Beverly Turner Lynds, and published in 1962. These dark nebulae were found from visual inspection of the Palomar Sky Survey photographic plates.

    [2] The Atacama Large Millimeter/submillimeter Array (ALMA), operated in part by ESO, observes in submillimetre and millimetre light and is ideal for the study of such very young stars in molecular clouds.

    [3] Such a young open star cluster can be seen here, and a more mature one here.

    See the full article here.

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  • richardmitnick 6:00 am on December 30, 2014 Permalink | Reply
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    From ESO: “Reflected Glory” 2011 


    European Southern Observatory

    16 February 2011

    Richard Hook
    ESO, La Silla, Paranal, E-ELT and Survey Telescopes Public Information Officer
    Garching bei München, Germany
    Tel: +49 89 3200 6655
    Cell: +49 151 1537 3591
    Email: rhook@eso.org

    The nebula Messier 78 takes centre stage in this image taken with the Wide Field Imager on the MPG/ESO 2.2-metre telescope at the La Silla Observatory in Chile, while the stars powering the bright display take a backseat. The brilliant starlight ricochets off dust particles in the nebula, illuminating it with scattered blue light. Igor Chekalin was the overall winner of ESO’s Hidden Treasures 2010 astrophotography competition with his image of this stunning object.

    n

    ESO WFI LaSilla
    ESO WFI

    ESO 2.2 meter telescope
    ESO 2.2 meter telescope interior
    MPG/ESO 2.2-metre telescope

    ESO LaSilla Long View
    ESO at LaSilla

    Messier 78 is a fine example of a reflection nebula. The ultraviolet radiation from the stars that illuminate it is not intense enough to ionise the gas to make it glow — its dust particles simply reflect the starlight that falls on them. Despite this, Messier 78 can easily be observed with a small telescope, being one of the brightest reflection nebulae in the sky. It lies about 1350 light-years away in the constellation of Orion (The Hunter) and can be found northeast of the easternmost star of Orion’s belt.

    This new image of Messier 78 from the MPG/ESO 2.2-metre telescope at the La Silla Observatory is based on data selected by Igor Chekalin in his winning entry to the Hidden Treasures competition [1].

    The pale blue tint seen in the nebula in this picture is an accurate representation of its dominant colour. Blue hues are commonly seen in reflection nebulae because of the way the starlight is scattered by the tiny dust particles that they contain: the shorter wavelength of blue light is scattered more efficiently than the longer wavelength red light.

    This image contains many other striking features apart from the glowing nebula. A thick band of obscuring dust stretches across the image from the upper left to the lower right, blocking the light from background stars. In the bottom right corner, many curious pink structures are also visible, which are created by jets of material being ejected from stars that have recently formed and are still buried deep in dust clouds.

    Two bright stars, HD 38563A and HD 38563B, are the main powerhouses behind Messier 78. However, the nebula is home to many more stars, including a collection of about 45 low mass, young stars (less than 10 million years old) in which the cores are still too cool for hydrogen fusion to start, known as T Tauri stars. Studying T Tauri stars is important for understanding the early stages of star formation and how planetary systems are created.

    Remarkably, this complex of nebulae has also changed significantly in the last ten years. In February 2004 the experienced amateur observer Jay McNeil took an image of this region with a 75 mm telescope and was surprised to see a bright nebula — the prominent fan shaped feature near the bottom of this picture — where nothing was seen on most earlier images. This object is now known as McNeil’s Nebula and it appears to be a highly variable reflection nebula around a young star.

    This colour picture was created from many monochrome exposures taken through blue, yellow/green and red filters, supplemented by exposures through an H-alpha filter that shows light from glowing hydrogen gas. The total exposure times were 9, 9, 17.5 and 15.5 minutes per filter, respectively.
    Notes

    [1] Igor Chekalin from Russia uncovered the raw data for this image of Messier 78 in ESO’s archives in the competition Hidden Treasures (eso1102). He processed the raw data with great skill, claiming first prize in the contest for his final image (Flickr link). ESO’s team of in-house image processing experts then independently processed the raw data at full resolution to produce the image shown here.

    See the full article here.

    Seethe recent short here.

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  • richardmitnick 7:57 am on December 17, 2014 Permalink | Reply
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    From ESO: “The Hot Blue Stars of Messier 47″ 


    European Southern Observatory

    17 December 2014
    Richard Hook
    ESO Public Information Officer
    Garching bei München, Germany
    Tel: +49 89 3200 6655
    Email: rhook@eso.org

    This spectacular image of the star cluster Messier 47 was taken using the Wide Field Imager camera, installed on the MPG/ESO 2.2-metre telescope at ESO’s La Silla Observatory in Chile. This young open cluster is dominated by a sprinkling of brilliant blue stars but also contains a few contrasting red giant stars.

    s

    ESO WFI LaSilla
    WFI

    ESO 2.2 meter telescope
    MPG/ESO 2.2-metre telescope

    ESO LaSilla Long View
    LaSilla

    Messier 47 is located approximately 1600 light-years from Earth, in the constellation of Puppis (the poop deck of the mythological ship Argo). It was first noticed some time before 1654 by Italian astronomer Giovanni Battista Hodierna and was later independently discovered by Charles Messier himself, who apparently had no knowledge of Hodierna’s earlier observation.

    Although it is bright and easy to see, Messier 47 is one of the least densely populated open clusters. Only around 50 stars are visible in a region about 12 light-years across, compared to other similar objects which can contain thousands of stars.

    Messier 47 has not always been so easy to identify. In fact, for years it was considered missing, as Messier had recorded the coordinates incorrectly. The cluster was later rediscovered and given another catalogue designation — NGC 2422. The nature of Messier’s mistake, and the firm conclusion that Messier 47 and NGC 2422 are indeed the same object, was only established in 1959 by Canadian astronomer T. F. Morris.

    The bright blue–white colours of these stars are an indication of their temperature, with hotter stars appearing bluer and cooler stars appearing redder. This relationship between colour, brightness and temperature can be visualised by use of the Planck curve. But the more detailed study of the colours of stars using spectroscopy also tells astronomers a lot more — including how fast the stars are spinning and their chemical compositions. There are also a few bright red stars in the picture — these are red giant stars that are further through their short life cycles than the less massive and longer-lived blue stars [1].

    p
    Planck curve

    By chance Messier 47 appears close in the sky to another contrasting star cluster — Messier 46. Messier 47 is relatively close, at around 1600 light-years, but Messier 46 is located around 5500 light-years away and contains a lot more stars, with at least 500 stars present. Despite containing more stars, it appears significantly fainter due to its greater distance.

    Messier 46 could be considered to be the older sister of Messier 47, with the former being approximately 300 million years old compared to the latter’s 78 million years. Consequently, many of the most massive and brilliant of the stars in Messier 46 have already run through their short lives and are no longer visible, so most stars within this older cluster appear redder and cooler.

    This image of Messier 47 was produced as part of the ESO Cosmic Gems programme [2].

    Notes

    [1] The lifetime of a star depends primarily on its mass. Massive stars, containing many times as much material as the Sun, have short lives measured in millions of years. On the other hand much less massive stars can continue to shine for many billions of years. In a cluster, the stars all have about the same age and same initial chemical composition. So the brilliant massive stars evolve quickest, become red giants sooner, and end their lives first, leaving the less massive and cooler ones to long outlive them.

    [2] 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.

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

     
  • richardmitnick 6:35 pm on December 14, 2014 Permalink | Reply
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    From Daily Galaxy: “The Messier 67 Mystery’ –Is Our Solar System an Orphan from a Distant Star Cluster?” 

    Daily Galaxy
    The Daily Galaxy

    December 14, 2014
    via ESO

    Astronomers over the decades have been searching for star clusters that could have shared our original region of the galaxy that come close to matching the composition and age of our Sun. The prime suspect so far One is a collective known as Messier 67, some 2,700 light-years distant that contains more than a hundred stars that bear a striking resemblance to the Sun. This cluster lies about 2500 light-years away in the constellation of Cancer (The Crab) and contains about 500 stars. Many of the cluster stars are fainter than those normally targeted for exoplanet searches and trying to detect the weak signal from possible planets pushed HARPS to the limit.

    1
    M67

    ESO HARPS
    ESO HARPS

    This past January, astronomers used the ESO’s HARPS planet hunter in Chile, along with other telescopes around the world, to discover three planets orbiting stars in Messier 67. Although more than one thousand planets outside the Solar System are now confirmed, only a handful have been found in star clusters. Remarkably one of these new exoplanets is orbiting a star that is a rare solar twin — a star that is almost identical to the Sun in all respects.

    Up to now, very few planets have been found inside star clusters. This is particularly odd as it is known that most stars are born in such clusters. Astronomers have wondered if there might be something different about planet formation in star clusters to explain this strange paucity.

    Star clusters come in two main types. Open clusters are groups of stars that have formed together from a single cloud of gas and dust in the recent past. They are mostly found in the spiral arms of a galaxy like the Milky Way. On the other hand globular clusters are much bigger spherical collections of much older stars that orbit around the centre of a galaxy. Despite careful searches, no planets have been found in a globular cluster and less than six in open clusters. Exoplanets have also been found in the past two years in the clusters NGC 6811 and Messier 44, and even more recently one has also been detected in the bright and nearby Hyades cluster.

    Anna Brucalassi (Max Planck Institute for Extraterrestrial Physics, Garching, Germany), lead author of the new study, and her team wanted to find out more. “In the Messier 67 star cluster the stars are all about the same age and composition as the Sun. This makes it a perfect laboratory to study how many planets form in such a crowded environment, and whether they form mostly around more massive or less massive stars.”

    The team used the HARPS planet-finding instrument on ESO’s 3.6-metre telescope at the La Silla Observatory. These results were supplemented with observations from several other observatories around the world. They carefully monitored 88 selected stars in Messier 67 over a period of six years to look for the tiny telltale motions of the stars towards and away from Earth that reveal the presence of orbiting planets.

    ESO 3.6m telescope & HARPS at LaSilla
    ESO/3.6 Meter Telescope and HARPS

    ESO LaSilla Long View
    ESO La Silla

    Three planets were discovered, two orbiting stars similar to the Sun and one orbiting a more massive and evolved red giant star. The first two planets both have about one third the mass of Jupiter and orbit their host stars in seven and five days respectively. The third planet takes 122 days to orbit its host and is more massive than Jupiter.

    The first of these planets proved to be orbiting a remarkable star — it is one of the most similar solar twins identified so far and is almost identical to the Sun (eso1337 – http://www.eso.org/public/news/eso1337/) . It is the first solar twin in a cluster that has been found to have a planet. Solar twins, solar analogues and solar-type stars are categories of stars according to their similarity to the Sun. Solar twins are the most similar to the Sun, as they have very similar masses, temperatures, and chemical abundances. Solar twins are very rare, but the other classes, where the similarity is less precise, are much more common.

    Two of the three planets are “hot Jupiters” — planets comparable to Jupiter in size, but much closer to their parent stars and hence much hotter. All three are closer to their host stars than the habitable zone where liquid water could exist.

    “These new results show that planets in open star clusters are about as common as they are around isolated stars — but they are not easy to detect,” adds Luca Pasquini (ESO, Garching, Germany), co-author of the new paper. “The new results are in contrast to earlier work that failed to find cluster planets, but agrees with some other more recent observations. We are continuing to observe this cluster to find how stars with and without planets differ in mass and chemical makeup.

    But is our Sun actually an orphan, ejected billions of years ago from Messier 67? Recent computer simulations of the motions of stars in the cluster and have projected the path that our solar system would have had to take if it were ejected and concluded that it doesn’t seem highly probable. It would require a very rare alignment of no less than two or three massive stars in Messier 67 to provide the gravitational slingshot to throw our solar system out to where we are today, not to mention that the gravitational forces would likely have torn our infant solar system to shreds.

    The scientific community is still in hot debate over our galactic origins, but there is little doubt that, one way or the other, we have been orphaned from somewhere in the outer regions of the Milky Way.

    See the full article here.

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  • richardmitnick 9:12 am on November 26, 2014 Permalink | Reply
    Tags: , , , , ESO La Silla   

    From ESO: “A Colourful Gathering of Middle-aged Stars” 


    European Southern Observatory

    26 November 2014
    Richard Hook
    ESO, Public Information Officer
    Garching bei München, Germany
    Tel: +49 89 3200 6655
    Cell: +49 151 1537 3591
    Email: rhook@eso.org

    The MPG/ESO 2.2-metre telescope at ESO’s La Silla Observatory in Chile has captured a richly colourful view of the bright star cluster NGC 3532. Some of the stars still shine with a hot bluish colour, but many of the more massive ones have become red giants and glow with a rich orange hue.

    f

    ESO 2.2 meter telescope
    ESO 2.2 meter telescope interior
    ESO 2.2 Meter Telescope at LaSilla

    ESO LaSilla Long View
    ESO/LaSilla

    NGC 3532 is a bright open cluster located some 1300 light-years away in the constellation of Carina (The Keel of the ship Argo). It is informally known as the Wishing Well Cluster, as it resembles scattered silver coins which have been dropped into a well. It is also referred to as the Football Cluster, although how appropriate this is depends on which side of the Atlantic you live. It acquired the name because of its oval shape, which citizens of rugby-playing nations might see as resembling a rugby ball.

    This very bright star cluster is easily seen with the naked eye from the southern hemisphere. It was discovered by French astronomer Nicolas Louis de Lacaille whilst observing from South Africa in 1752 and was catalogued three years later in 1755. It is one of the most spectacular open star clusters in the whole sky.

    NGC 3532 covers an area of the sky that is almost twice the size of the full Moon. It was described as a binary-rich cluster by John Herschel who observed “several elegant double stars” here during his stay in southern Africa in the 1830s. Of additional, much more recent, historical relevance, NGC 3532 was the first target to be observed by the NASA/ESA Hubble Space Telescope, on 20 May 1990.

    NASA Hubble Telescope
    NASA Hubble schematic
    NASA/ESA Hubble

    This grouping of stars is about 300 million years old. This makes it middle-aged by open star cluster standards [1]. The cluster stars that started off with moderate masses are still shining brightly with blue-white colours, but the more massive ones have already exhausted their supplies of hydrogen fuel and have become red giant stars. As a result the cluster appears rich in both blue and orange stars. The most massive stars in the original cluster will have already run through their brief but brilliant lives and exploded as supernovae long ago. There are also numerous less conspicuous fainter stars of lower mass that have longer lives and shine with yellow or red hues. NGC 3532 consists of around 400 stars in total.

    The background sky here in a rich part of the Milky Way is very crowded with stars. Some glowing red gas is also apparent, as well as subtle lanes of dust that block the view of more distant stars. These are probably not connected to the cluster itself, which is old enough to have cleared away any material in its surroundings long ago.

    This image of NGC 3532 was captured by the Wide Field Imager instrument at ESO’s La Silla Observatory in February 2013.

    ESO Wide Field Imager 2.2m LaSilla
    WFI at LaSilla

    Notes

    [1] Stars with masses many times greater than the Sun have lives of just a few million years, the Sun is expected to live for about ten billion years and low-mass stars have expected lives of hundreds of billions of years — much greater than the current age of the Universe.

    See the full article here.

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  • richardmitnick 10:33 am on November 19, 2014 Permalink | Reply
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    From SPACE.com: “Asteroid Found with Rings! First-of-Its-Kind Discovery Stuns Astronomers (Video, Images)” 

    space-dot-com logo

    SPACE.com

    March 26, 2014
    Nola Taylor Redd

    Scientists have made a stunning discovery in the outer realm of the solar system — an asteroid with its own set of rings that orbits the sun between Saturn and Uranus. The space rock is the first non-planetary object ever found to have its own ring system, researchers say.

    The pair of space rock rings encircle the asteroid Chariklo. They were most likely formed after a collision scattered debris around the asteroid, according to a new study unveiled today (March 27). The asteroid rings also suggests the presence of a still-undiscovered moon around Chariklo that’s keeping them stable, researchers said.

    “We weren’t looking for a ring and didn’t think small bodies like Chariklo had them at all, so the discovery — and the amazing amount of detail we saw in the system — came as a complete surprise!” study leader Felipe Braga-Ribas, of the National Observatory in Brazil said in a statement today.

    Astronomers used seven telescopes, but just one revealed the pair of rings orbiting the rocky Chariklo. The asteroid’s 155-mile diameter (250 kilometers) is dwarfed by the giant gas planets, the only other bodies known to have rings.

    “This discovery shows that size is not important in order to have — or not have — rings,” Felipe Braga-Ribas, of the National Observatory in Brazil, told Space.com by email.

    An asteroid among giants

    On June 3, 2013, Braga-Ribas led a team of astronomers in observing Chariklo as it passed in front of a distant star — a process known as an occultation. As the asteroid traveled, it blocked light from the star, enabling scientists to learn more about it.

    The astronomers were surprised to discover that a few seconds before and after the main occultation, the light dimmed slightly, indicating that something circled the rocky asteroid. By comparing the data gathered from seven different telescopes, the team was able to identify the shape, size and orientation of the rings.

    The system consists of a dense, 4-mile-wide (7 km) ring near the planet, and a smaller 2-mile-wide (3 km) ring farther out.

    From the surface of the asteroid, “they would be two spectacular sharp and really bright rings, crossing all the sky,” Braga-Ribas said. “They would be noticeably close, as they are at about 1/1,000 of the moon’s distance from us,” he added.

    He went on to say that the larger, inner ring would block the view of the outer ring from the ground. The rings are similar to those around Saturn, in that both are very dense, bright and possibly formed by rock and water ice. But their scales are quite different.

    “The whole Chariklo system would fit about 12 times in the Cassini Division,” Braga-Ribas said, referring to the largest gap in Saturn’s rings.

    Particles orbiting Chariklo also travel more slowly — only tens of meters per second, compared with tens of kilometers per second in the rings of Saturn.

    While Saturn is the most well-known ringed body in the solar system, Jupiter, Neptune and Uranus also have their own, fainter rings. These gas giants significantly dwarf the smaller asteroid.

    Astronomers utilized seven telescopes, most of which were located in South America. Of them, only the European Southern Observatory’s La Silla telescope in Chile was able to capture the small gap between the rings.

    ESO LaSilla Long View
    ESO/LaSilla

    “This was possible due to the use of the ‘Lucky Imager,’ a fast and sensible camera that obtained a sequence of images like a video at a rate of 10 images per second,” Braga-Ribas said. “As the stellar occultation by both rings lasted for 0.6 seconds in total, it was able to ‘see’ the rings in detail.”

    The other telescopes had exposure times greater than 0.7 seconds, so they were only able to observe a single gap in the light.

    What’s so special about this asteroid to make it have rings?
    “Chariklo seems to be nothing special, otherwise,” Joseph Burns, of Cornell University, told Space.com by email. Burns was not a member of Braga-Ribas’ team, but he studies planetary rings and the small bodies of the solar system. He authored a perspective article that appeared alongside the new findings.

    Chariklo may not be the only nonplanetary body to have rings, Braga-Ribas said. “Rings may be a much more common property than we thought,” he said.

    The research and Burns’ accompanying article were published online today (March 26) in the journal Nature.

    Chariklo’s ‘toy ring’

    Chariklo is the largest of the centaurs, several bodies in the outer solar system whose orbits cross — and are changed by — the outer planets. The centaurs share characteristics with both asteroids and comets, and are thought to come from the Kuiper Belt region beyond Pluto. Rocky Chariklo appears to be more asteroid than comet in composition, according to the paper.

    kb
    Kuiper Belt

    This placement may help to explain the presence of Chariklo’s rings and their absence in the asteroid belt that lies between Mars and Jupiter. The rocky inner planets and the asteroid belt lie closer to the sun, and experience stronger forces from the solar wind, which can more efficiently blow small particles away from objects they might otherwise orbit, Braga-Ribas said.

    Collisions in the fast-moving asteroid belt are also violent processes due to their faster orbital speeds. Crashes between the nearby rocky bodies may wind up hurling any potential ring material away too quickly. The collision that likely created Chariklo’s rings would have had to have been a slow-moving impact. The asteroid’s small size means it has very little gravity, allowing fast-moving objects to easily escape from its orbit; the asteroid would only have been able to hold on to slower-traveling objects.

    The presence of a ring system answers questions about why the asteroid has brightened since observations in 2008. Originally viewed edge-on, the rings have become visible over the last five years as their inclination changed.

    Twice in its 29-year orbit, Saturn’s rings act the same way, appearing as a thin line to observers on Earth, Burns said. “This behavior confounded Galileo, as viewed through his crude telescope, on his discovery of Saturn’s rings,” Burns said. “It took many more observers and nearly 50 years before the rings’ nature was understood by Christiaan Huygens.”

    The age of the rings remains another mystery. Over the course of a few million years, the small pieces of a ring system should spread out. Because they are still contained as a ring, the authors concluded that either the system is very young, or the asteroid hosts a small moon that shepherds and confines the particles in their orbit. The moon would be about as massive as both rings combined, and would easily escape detection given Chariklo’s great distance.

    “Shepherds are the preferred — and basically only — explanation,” Burns said. “But Saturn’s and Uranus’ rings have many gaps where we should see shepherds and we don’t. Something is missing in our understanding. Maybe studying Chariklo’s toy rings will bring us ideas.”

    If a missing moon circles the asteroid, keeping the rings in line, then the system could have lasted since the dawn of the solar system, Braga-Ribas said, adding that the disturbance of the gas giant that moved Chariklo to its present-day orbit would require a very close pass to disturb the ring system, indicating that they could have survived the migration.

    Studying the stability of Chariklo’s rings can tell astronomers about the environment required to form and maintain them — a process that can be used to understand the dynamics of the early stages of the solar system.

    On a wider scale, the tiny ringed asteroid can also help scientists to understand more about how galaxies form.

    “The shepherd mechanism seems to be universal from the giant planets to the small minor planet,” Braga-Ribas said. “This mechanism may be acting in other kinds of debris discs, such as proto-planetary nebulae and galaxies.”

    See the full article, with other material, here.

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  • richardmitnick 1:30 pm on October 22, 2014 Permalink | Reply
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    From ESO: “Two Families of Comets Found Around Nearby Star” 


    European Southern Observatory

    22 October 2014
    Contacts

    Alain Lecavelier des Etangs
    Institut d’astrophysique de Paris (IAP)/CNRS/UPMC
    France
    Tel: +33-1-44-32-80-77
    Cell: +33 6 21 75 12 03
    Email: lecaveli@iap.fr

    Flavien Kiefer
    Institut d’astrophysique de Paris (IAP)/CNRS/UPMC and School of Physics and Astronomy, Tel Aviv University
    France / Israel
    Tel: +972-502-838-163
    Email: kiefer@iap.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

    The HARPS instrument at ESO’s La Silla Observatory in Chile has been used to make the most complete census of comets around another star ever created. A French team of astronomers has studied nearly 500 individual comets orbiting the star Beta Pictoris and has discovered that they belong to two distinct families of exocomets: old exocomets that have made multiple passages near the star, and younger exocomets that probably came from the recent breakup of one or more larger objects. The new results will appear in the journal Nature on 23 October 2014.

    ESO HARPS
    ESO HARPS at La Silla

    ESO LaSilla Long View
    La Silla

    comets

    Beta Pictoris is a young star located about 63 light-years from the Sun. It is only about 20 million years old and is surrounded by a huge disc of material — a very active young planetary system where gas and dust are produced by the evaporation of comets and the collisions of asteroids.

    Flavien Kiefer (IAP/CNRS/UPMC), lead author of the new study sets the scene: “Beta Pictoris is a very exciting target! The detailed observations of its exocomets give us clues to help understand what processes occur in this kind of young planetary system.”

    For almost 30 years astronomers have seen subtle changes in the light from Beta Pictoris that were thought to be caused by the passage of comets in front of the star itself. Comets are small bodies of a few kilometres in size, but they are rich in ices, which evaporate when they approach their star, producing gigantic tails of gas and dust that can absorb some of the light passing through them. The dim light from the exocomets is swamped by the light of the brilliant star so they cannot be imaged directly from Earth.

    To study the Beta Pictoris exocomets, the team analysed more than 1000 observations obtained between 2003 and 2011 with the HARPS instrument on the ESO 3.6-metre telescope at the La Silla Observatory in Chile.

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

    The researchers selected a sample of 493 different exocomets. Some exocomets were observed several times and for a few hours. Careful analysis provided measurements of the speed and the size of the gas clouds. Some of the orbital properties of each of these exocomets, such as the shape and the orientation of the orbit and the distance to the star, could also be deduced.

    This analysis of several hundreds of exocomets in a single exo-planetary system is unique. It revealed the presence of two distinct families of exocomets: one family of old exocomets whose orbits are controlled by a massive planet [1], and another family, probably arising from the recent breakdown of one or a few bigger objects. Different families of comets also exist in the Solar System.

    The exocomets of the first family have a variety of orbits and show a rather weak activity with low production rates of gas and dust. This suggests that these comets have exhausted their supplies of ices during their multiple passages close to Beta Pictoris [2].

    The exocomets of the second family are much more active and are also on nearly identical orbits [3]. This suggests that the members of the second family all arise from the same origin: probably the breakdown of a larger object whose fragments are on an orbit grazing the star Beta Pictoris.

    Flavien Kiefer concludes: “For the first time a statistical study has determined the physics and orbits for a large number of exocomets. This work provides a remarkable look at the mechanisms that were at work in the Solar System just after its formation 4.5 billion years ago.”
    Notes

    [1] A giant planet, Beta Pictoris b, has also been discovered in orbit at about a billion kilometres from the star and studied using high resolution images obtained with adaptive optics.

    [2] Moreover, the orbits of these comets (eccentricity and orientation) are exactly as predicted for comets trapped in orbital resonance with a massive planet. The properties of the comets of the first family show that this planet in resonance must be at about 700 million kilometres from the star — close to where the planet Beta Pictoris b was discovered.

    [3] This makes them similar to the comets of the Kreutz family in the Solar System, or the fragments of Comet Shoemaker-Levy 9, which impacted Jupiter in July 1994.
    More information

    This research was presented in a paper entitled Two families of exocomets in the Beta Pictoris system which will be published in the journal Nature on 23 October 2014.

    The team is composed of F. Kiefer (Institut d’astrophysique de Paris [IAP], CNRS, Université Pierre & Marie Curie-Paris 6, Paris, France), A. Lecavelier des Etangs (IAP), J. Boissier (Institut de radioastronomie millimétrique, Saint Martin d’Hères, France), A. Vidal-Madjar (IAP), H. Beust (Institut de planétologie et d’astrophysique de Grenoble [IPAG], CNRS, Université Joseph Fourier-Grenoble 1, Grenoble, France), A.-M. Lagrange (IPAG), G. Hébrard (IAP) and R. Ferlet (IAP).

    See the full article here.

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