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  • richardmitnick 3:58 pm on December 15, 2015 Permalink | Reply
    Tags: , , ESO VLT,   

    From ESO: “Mind the Gap” 

    [I picked this up from 2008 because it relates to an ALMA release due out on 12.16.15.]


    European Southern Observatory

    8 September 2008
    Klaus Pontoppidan
    California Institute of Technology
    Pasadena, USA
    Tel: +1 626 395 4900
    Cell: +1 626 679 5793
    Email: pontoppi@gps.caltech.edu

    Ewine van Dishoeck
    Leiden University
    Leiden, Netherlands
    Tel: +31 71 527 58 14
    Email: ewine@strw.leidenuniv.nl

    VLT instrument hints at the presence of planets in young gas discs

    1

    Astronomers have been able to study planet-forming discs around young Sun-like stars in unsurpassed detail, clearly revealing the motion and distribution of the gas in the inner parts of the disc. This result, which possibly implies the presence of giant planets, was made possible by the combination of a very clever method enabled by ESO’s Very Large Telescope.

    Planets could be home to other forms of life, so the study of exoplanets ranks very high in contemporary astronomy. More than 300 planets are already known to orbit stars other than the Sun, and these new worlds show an amazing diversity in their characteristics. But astronomers don’t just look at systems where planets have already formed – they can also get great insights by studying the discs around young stars where planets may currently be forming. “This is like going 4.6 billion years back in time to watch how the planets of our own Solar System formed,” says Klaus Pontoppidan from Caltech, who led the research.

    Pontoppidan and colleagues have analysed three young analogues of our Sun that are each surrounded by a disc of gas and dust from which planets could form. These three discs are just a few million years old and were known to have gaps or holes in them, indicating regions where the dust has been cleared and the possible presence of young planets.

    The new results not only confirm that gas is present in the gaps in the dust, but also enable astronomers to measure how the gas is distributed in the disc and how the disc is oriented. In regions where the dust appears to have been cleared out, molecular gas is still highly abundant. This can either mean that the dust has clumped together to form planetary embryos, or that a planet has already formed and is in the process of clearing the gas in the disc.

    For one of the stars, SR 21, a likely explanation is the presence of a massive giant planet orbiting at less than 3.5 times the distance between the Earth and the Sun, while for the second star, HD 135344B, a possible planet could be orbiting at 10 to 20 times the Earth-Sun distance. The observations of the third star, TW Hydrae, may also require the presence of one or two planets.

    “Our observations with the CRIRES instrument on ESO’s Very Large Telescope clearly reveal that the discs around these three young, Sun-like stars are all very different and will most likely result in very different planetary systems,” concludes Pontoppidan.

    ESO CRIRES
    CRIRES

    “Nature certainly does not like to repeat herself” [1].

    “These kinds of observations complement the future work of the ALMA observatory, which will be imaging these discs in great detail and on a larger scale,” adds Ewine van Dishoeck, from Leiden Observatory, who works with Pontoppidan.

    To study the gaps in dust discs that are the size of the Solar System around stars that are located up to 400 light-years away is a daunting challenge that requires a clever solution and the best possible instruments [2].

    “Traditional imaging cannot hope to see details on the scale of planetary distances for objects located so far away,” explains van Dishoeck. “Interferometry can do better but won’t allow us to follow the motion of the gas.”

    Astronomers used a technique known as spectro-astrometric imaging to give them a window into the inner regions of the discs where Earth-like planets may be forming. They were able not only to measure distances as small as one-tenth the Earth-Sun distance, but to measure the velocity of the gas at the same time [3].

    “The particular configuration of the instrument and the use of adaptive optics allows astronomers to carry out observations with this technique in a very user-friendly way: as a consequence, spectro-astrometric imaging with CRIRES can now be routinely performed,” says team member Alain Smette, from ESO [4].

    Notes

    Pontoppidan, K. M. et. al. 2008, Spectro-Astrometric Imaging of Molecular Gas Within Protoplanetary Disk Gaps, Astrophysical Journal, 684, 1323, 10 September 2008. Team members are Klaus M. Pontoppidan, Geoffrey A. Blake, and Michael J. Ireland (California Institute of Technology, Pasadena, USA), Ewine F. van Dishoeck (Leiden Observatory, The Netherlands, and Max-Planck-Institute for Extraterrestrial Physics, Garching, Germany – MPE), Alain Smette (ESO, Chile), and Joanna Brown (MPE).

    [1] The discs are about an hundred astronomical units (AU – the mean distance between the Earth and the Sun, or 149.6 million kilometres) across, but the stars are more than 200 light-years away (one light-year is 200 000 AU). To resolve structures on 1 AU scales in these systems corresponds to reading the license plate on a car at a distance of 2000 km – roughly the distance from Stockholm to Lisbon.

    [2] CRIRES, the near-infrared spectrograph attached to ESO’s Very Large Telescope, is fed from the telescope through an adaptive optics module which corrects for the blurring effect of the atmosphere and so makes it possible to have a very narrow slit with a high spectral dispersion: the slit width is 0.2 arcsecond and the spectral resolution is 100 000. Using spectro-astrometry, an ultimate spatial resolution of better than 1 milli-arcsecond is achieved.

    [3] The core of the spectro-astrometry imaging technique relies on the ability of CRIRES to be positioned very precisely on the sky, while retaining the ability to spread the light into a spectrum so that wavelength differences of 1 part in 100 000 can be detected. More precisely, the astronomers measure the centroid in the spatial direction of a spectrally resolved emission line: effectively, astronomers take a sharp emission line – a clear fingerprint of a molecule in the gas – and use data from several slit positions to locate the sources of particular emission lines, and hence to map the distribution of the gas with much greater precision than can be achieved by straightforward imaging. The astronomers have obtained spectra of the discs centred at wavelengths of 4.715 microns at 6 different position angles.

    [4] Alain Smette is the CRIRES Instrument Scientist.

    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 NTT
    NTT

    ESO VLT Survey telescope
    VLT Survey Telescope

    ALMA Array
    ALMA

    ESO E-ELT
    E-ELT

    ESO APEX
    Atacama Pathfinder Experiment (APEX) Telescope

     
  • richardmitnick 10:16 am on December 9, 2015 Permalink | Reply
    Tags: , , ESO VLT, NGC 5291   

    From ESO: “VLT Revisits a Curious Cosmic Collision” 


    European Southern Observatory

    9 December 2015
    Jérémy Fensch
    Laboratoire AIM Paris-Saclay, CEA/IRFU/SAp, Universite Paris Diderot
    Gif-sur-Yvette, France
    Email: jeremy.fensch@gmail.com

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

    1

    The spectacular aftermath of a 360 million year old cosmic collision is revealed in great detail in new images from ESO’s Very Large Telescope at the Paranal Observatory. Among the debris is a rare and mysterious young dwarf galaxy. This galaxy is providing astronomers with an excellent opportunity to learn more about similar galaxies that are expected to be common in the early Universe, but are normally too faint and distant to be observed by current telescopes.

    NGC 5291, the hazy, golden oval dominating the centre of this image, is an elliptical galaxy located nearly 200 million light-years away in the constellation of Centaurus (The Centaur). Over 360 million years ago, NGC 5291 was involved in a dramatic and violent collision as another galaxy travelling at immense speeds barrelled into its core. The cosmic crash ejected huge streams of gas into nearby space, which later coalesced into a ring formation around NGC 5291 [1].

    Over time, material in this ring gathered and collapsed into dozens of star-forming regions and several dwarf galaxies, revealed as pale blue and white regions scattered around NGC 5291 in this new image from the FORS instrument, mounted on the VLT.

    ESO FORS1
    FORS

    The most massive and luminous clump of material, to the right of NGC 5291, is one of these dwarf galaxies and is known as NGC 5291N.

    The Milky Way, like all large galaxies, is believed to have formed through the build-up of smaller dwarf galaxies in the early years of the Universe. These small galaxies, if they have survived on their own up to the present day, now normally contain many extremely old stars.

    Yet NGC 5291N appears to contain no old stars. Detailed observations with the MUSE spectrograph [2] also found that the outer parts of the galaxy had properties typically associated with the formation of new stars, but what was observed is not predicted by current theoretical models. Astronomers suspect that these unusual aspects may be the result of massive collisions of gas in the region.

    ESO MUSE
    MUSE

    NGC 5291N doesn’t look like a typical dwarf galaxy, but instead it shares a striking number of similarities with the clumpy structures present within many of the star-forming galaxies in the distant Universe. This makes it a unique system in our local Universe and an important laboratory for the study of early gas-rich galaxies, which are normally much too distant to be observed in detail by current telescopes.

    This unusual system has previously been observed by a wide range of ground-based facilities, including ESO’s 3.6-metre telescope at the La Silla Observatory [3].

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

    However, the capabilities of MUSE, FORS and the Very Large Telescope have only now allowed some of the history and properties of NGC 5291N to be determined.

    Future observations, including those by ESO’s European Extremely Large Telescope (E-ELT), may allow astronomers to further unravel this dwarf galaxy’s remaining mysteries.

    ESO E-ELT
    Future E-ELT

    Notes

    [1] NGC 5291 is currently also interacting more gently with MCG-05-33-005 — or the Seashell Galaxy — the unusual comma-shaped galaxy appearing to leech off NGC 5291’s luminous core.

    3
    Seashell Galaxy

    [2] NGC 5291N was observed using integral field spectrography during MUSE’s first Science Verification run. Integral field spectrography collects a spectrum at every point on the sky, providing a powerful three-dimensional view of the target. The MUSE observations revealed unexpected oxygen and hydrogen emission lines in the outskirts of NGC 5291N.

    [3] NGC 5291 was studied by astronomers using ESO’s 3.6-metre telescope at the La Silla Observatory back in 1978. These observations revealed large amounts of material in the intergalactic space around the galaxy, which we now know to be the star-forming regions and several dwarf galaxies created from the collapse of the galaxy’s gaseous ring.

    More information

    This research was presented in a paper entitled “Ionization processes in a local analogue of distant clumpy galaxies: VLT MUSE IFU spectroscopy and FORS deep images of the TDG NGC 5291N”, by J. Fensch et al., to appear in the journal Astronomy & Astrophysics.

    The team is composed of J. Fensch (Laboratoire AIM Paris-Saclay, CEA/IRFU/SAp, Universite Paris Diderot, Gif-sur-Yvette, France [CEA]), P.-A. Duc (CEA) , P. M. Weilbacher (Leibniz-Institut für Astrophysik, Potsdam, Germany), M. Boquien (University of Cambridge, United Kingdom; Universidad de Antofagasta, Antofagasta, Chile) and E. Zackrisson (Uppsala University, Uppsala, Sweden).

    Research paper

    Another view of NGC 5291
    2
    A image of en:NGC 5291 by the Spitzer Space Telescope

    NASA Spitzer Telescope
    NASA/Spitzer

    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 VLT Survey telescope
    VLT Survey Telescope

    ALMA Array
    ALMA

    ESO E-ELT
    E-ELT

    ESO APEX
    Atacama Pathfinder Experiment (APEX) Telescope

     
  • richardmitnick 9:52 am on December 7, 2015 Permalink | Reply
    Tags: , , ESO VLT,   

    From Hubble: “Hubblecast 88 Mysterious Ripples Found Racing Through Planet-forming Disc” 

    NASA Hubble Telescope

    Hubble

    Using images from the NASA/ESA Hubble Space Telescope and ESO’s Very Large Telescope, astronomers have discovered unique and totally unexpected structures within the dusty disc around the star AU Microscopii.


    download mp4 video here.

    ESO VLT Interferometer
    ESO VLT

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

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    The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA’s Goddard Space Flight Center manages the telescope. The Space Telescope Science Institute (STScI), is a free-standing science center, located on the campus of The Johns Hopkins University and operated by the Association of Universities for Research in Astronomy (AURA) for NASA, conducts Hubble science operations.

    ESA50 Logo large

    AURA Icon

     
  • richardmitnick 12:13 pm on November 27, 2015 Permalink | Reply
    Tags: , , , ESO VLT   

    From ESO: “Laser Guide Star Units Accepted and Shipped to Chile” 


    European Southern Observatory

    27 November 2015
    Domenico Bonaccini Calia
    ESO
    Garching bei München, Germany
    Tel: +49 89 3200 6567
    Email: dbonacci@eso.org

    Wolfgang Hackenberg
    ESO
    Garching bei München, Germany
    Tel: +49 89 3200 6782
    Email: whackenb@eso.org

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

    1
    One of the units of the Four Laser Guide Star Facility for the VLT

    All four laser guide star units that form the Four Laser Guide Star Facility — a core part of the Adaptive Optics Facility (AOF) for ESO’s Very Large Telescope — have now been accepted and are being shipped to Chile. This is a major step towards establishing VLT Unit Telescope 4 as a fully adaptive telescope with much enhanced image quality.

    ESO 4LGSF Adaptive Optics Facility (AOF)
    The 4LGSF is to be installed as a subsystem of the Adaptive Optics Facility (AOF) on UT4 of the VLT, to provide the AO systems GALACSI/MUSE and GRAAL/HAWK-I with four sodium laser guide stars (LGSs), as artificial reference sources for the high-order AO corrections.

    The 4LGSF will deploy four modular LGS Units (see below) at the UT4 Centrepiece, as shown in Figure 1. Each LGS Unit consists of the Launch Telescope System incl. 20W Laser Head and two close-by cabinets, one hosting the Laser Unit electronics (incl. the pump fibre laser unit) and the other containing the local control electronics. Two additional 4LGSF cabinets are installed on a new 4LGSF Platform underneath the Nasmyth B platform and contain the computers for independently controlling the four LGS Units. The 4LGSF Platform also hosts the heat exchanger for the laser cooling system.

    An adaptive optics system uses sensors to analyse the atmospheric turbulence and a deformable mirror integrated in the telescope to correct for the image distortions caused by the atmosphere. But a bright point-like star very close in the sky to the object being studied is essential, so that the turbulence can be accurately characterised.

    Finding a natural star in the right place for this role is unlikely. So, to make the correction of the atmospheric turbulence possible everywhere in the sky, for all possible science targets, an artificial star is needed. Such stars can be created by projecting a powerful laser beam into the sky onto the sodium layer, where it creates a bright glow that appears star-like from the ground.

    By measuring the atmospherically induced motions and distortions of this artificial star, and making tiny adjustments to the deformable secondary mirror one thousand times per second, the telescope can produce images with much greater sharpness than is possible without adaptive optics.

    The first Adaptive Optics Facility laser guide star unit was installed on the VLT and successfully tested in situ earlier this year. These tests have confirmed the sound design implemented by ESO, in collaboration with European industry and scientific institutes [1]. Tests on VLT Unit Telescope 4 in Chile showed high optical quality, providing an almost perfect artificial star image, and high efficiency of the sodium layer excitation. These successes mean that the team can proceed with preliminary tests with GRAAL, the adaptive optics module feeding HAWK-I, the wide-field imager on Unit Telescope 4; all further steps towards the full commissioning of the Adaptive Optics Facility at Paranal.

    ESO Graal
    GRAAL

    ESO HAWK-I
    Hawk-I

    The Adaptive Optics Facility will use four lasers simultaneously, which will allow better characterisation of the atmosphere’s properties — and hence a larger field of view where the image is corrected — than is possible with just one laser.

    When fully installed, the Adaptive Optics Facility will feed light into two instruments, HAWK-I (in conjunction with GRAAL) and the integral field spectrograph, MUSE, (in conjunction with GALACSI).

    ESO MUSE
    MUSE

    ESO GALACSI
    GALACSI

    Notes

    [1] The companies involved include: TOPTICA, Germany; TNO, The Netherlands; MPB Communications, Canada; Optec, Italy; Astrel, Italy; and Laseroptik, Germany. In addition INAF–Osservatorio di Roma, Italy has made significant contributions to the project.

    Links

    More information about the laser
    More information about the deformable secondary mirror
    More information about the laser launch telescope

    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 VLT Survey telescope
    VLT Survey Telescope

    ALMA Array
    ALMA

    ESO E-ELT
    E-ELT

    ESO APEX
    Atacama Pathfinder Experiment (APEX) Telescope

     
  • richardmitnick 4:55 pm on November 25, 2015 Permalink | Reply
    Tags: , , , ESO VLT   

    From ESO: “MUSE Observations Enable Prediction of Once-in-a-lifetime Supernova Replay” 


    European Southern Observatory

    25 November 2015
    Claudio Grillo
    Dark Cosmology Centre, Niels Bohr Institute
    University of Copenhagen, Denmark
    Email: grillo@dark-cosmology.dk

    Piero Rosati
    Department of Physics and Earth Science
    University of Ferrara
    Email: rosati@fe.infn.it

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

    1

    Astronomers have used the Multi Unit Spectroscopic Explorer (MUSE), attached to ESO’s Very Large Telescope (VLT) at the Paranal Observatory, to take advantage of a once-in-a-lifetime opportunity to test their understanding of massive clusters of galaxies. They are making the first ever prediction of an observational event in the distant Universe before it actually becomes visible.

    Images of the galaxy cluster MACS J1149+2223, taken by the NASA/ESA Hubble Space Telescope in November 2014, revealed a distant exploding star — a supernova — like no other ever seen. Nicknamed Refsdal [1], it is the first supernova to be split into four separate images through the process of gravitational lensing, forming an almost perfect Einstein Cross around one of the cluster’s galaxies.

    ESO MUSE
    MUSE

    2
    The European Space Agency’s Faint Object Camera on board NASA’s Hubble Space Telescope has provided astronomers with the most detailed image ever taken of the gravitational lens G2237 + 0305 — sometimes referred to as the Einstein Cross. The photograph shows four images of a very distant quasar which has been multiple-imaged by a relatively nearby galaxy acting as a gravitational lens. The angular separation between the upper and lower images is 1.6 arcseconds.
    Date 13 September 1990

    Gravitational lensing is a consequence of [Albert] Einstein’s theory of general relativity. The paper stating the equations of this fundamental change in our understanding of gravity was published on 25 November 1915, exactly one century ago.

    Critical observations of the precise distances to galaxies in the region of MACS J1149+2223 were made using MUSE in early 2015. They have enabled astronomers to model the matter distribution inside the behemoth galaxy cluster more precisely than ever before. This has led to several predictions of when and where another image of the distant supernova — an instant replay on the biggest screen imaginable — will appear.

    Because the light that forms the multiple images of the supernova takes paths to the Earth with different lengths, they appear at different times as well as at different points on the sky.

    Using all the available MUSE data, in combination with Hubble observations, a team of astronomers led by Claudio Grillo (Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Denmark) have predicted that a further replay will peak in brightness between March and June 2016, with a possible first detection before the end of 2015. They can also anticipate not only where and when the supernova is expected to become visible again, but also approximately how bright it will appear.

    Hubble is now being periodically pointed at the cluster in hopes of catching the once-in-a-lifetime event, putting the astronomers’ models to the ultimate test in the process.

    These observations highlight the vital role that MUSE and the VLT play in the exploration of the distant Universe, as well as the synergy between Hubble and ground-based observatories.

    Notes

    [1] It is named after the late Norwegian astronomer Sjur Refsdal, who was a pioneer of the study of gravitational lenses.

    Links

    Science paper (Grillo et al)
    Related science paper (Jauzac et al)
    Related science paper (Treu et al)
    Related science paper (Karman et al)
    Related announcement from Hubble

    See the full article here .

    Please help promote STEM in your local schools.
    STEM Icon

    Stem Education Coalition
    Visit ESO in Social Media-

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    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 VLT Survey telescope
    VLT Survey Telescope

    ALMA Array
    ALMA

    ESO E-ELT
    E-ELT

    ESO APEX
    Atacama Pathfinder Experiment (APEX) Telescope

     
  • richardmitnick 9:09 am on November 25, 2015 Permalink | Reply
    Tags: Aging Star’s Weight Loss Secret Revealed, , , ESO VLT   

    From ESO: “Aging Star’s Weight Loss Secret Revealed” 


    European Southern Observatory

    25 November 2015
    Peter Scicluna
    Academia Sinica Institute for Astronomy and Astrophysics
    Taiwan
    Tel: +886 (02) 2366 5420
    Email: peterscicluna@asiaa.sinica.edu.tw

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

    Giant star caught in the act of slimming down

    1

    A team of astronomers using ESO’s Very Large Telescope (VLT) has captured the most detailed images ever of the hypergiant star VY Canis Majoris. These observations show how the unexpectedly large size of the particles of dust surrounding the star enable it to lose an enormous amount of mass as it begins to die. This process, understood now for the first time, is necessary to prepare such gigantic stars to meet explosive demises as supernovae.

    VY Canis Majoris is a stellar goliath, a red hypergiant, one of the largest known stars in the Milky Way. It is 30–40 times the mass of the Sun and 300 000 times more luminous. In its current state, the star would encompass the orbit of Jupiter, having expanded tremendously as it enters the final stages of its life.

    The new observations of the star used the SPHERE instrument on the VLT.

    ESO SPHERE
    SPHERE

    The adaptive optics system of this instrument corrects images to a higher degree than earlier adaptive optics systems. This allows features very close to bright sources of light to be seen in great detail [1]. SPHERE clearly revealed how the brilliant light of VY Canis Majoris was lighting up clouds of material surrounding it.

    And by using the ZIMPOL mode of SPHERE, the team could not only peer deeper into the heart of this cloud of gas and dust around the star, but they could also see how the starlight was scattered and polarised by the surrounding material. These measurements were key to discovering the elusive properties of the dust.

    Careful analysis of the polarisation results revealed these grains of dust to be comparatively large particles, 0.5 micrometres across, which may seem small, but grains of this size are about 50 times larger than the dust normally found in interstellar space.

    Throughout their expansion, massive stars shed large amounts of material — every year, VY Canis Majoris sees 30 times the mass of the Earth expelled from its surface in the form of dust and gas. This cloud of material is pushed outwards before the star explodes, at which point some of the dust is destroyed, and the rest cast out into interstellar space. This material is then used, along with the heavier elements created during the supernova explosion, by the next generation of stars, which may make use of the material for planets.

    Until now, it had remained mysterious how the material in these giant stars’ upper atmospheres is pushed away into space before the host explodes. The most likely driver has always seemed to be radiation pressure, the force that starlight exerts. As this pressure is very weak, the process relies on large grains of dust, to ensure a broad enough surface area to have an appreciable effect [2].

    “Massive stars live short lives,” says lead author of the paper, Peter Scicluna, of the Academia Sinica Institute for Astronomy and Astrophysics, Taiwan. “When they near their final days, they lose a lot of mass. In the past, we could only theorise about how this happened. But now, with the new SPHERE data, we have found large grains of dust around this hypergiant. These are big enough to be pushed away by the star’s intense radiation pressure, which explains the star’s rapid mass loss.”

    The large grains of dust observed so close to the star mean that the cloud can effectively scatter the star’s visible light and be pushed by the radiation pressure from the star. The size of the dust grains also means much of it is likely to survive the radiation produced by VY Canis Majoris’ inevitable dramatic demise as a supernova [3]. This dust then contributes to the surrounding interstellar medium, feeding future generations of stars and encouraging them to form planets.
    Notes

    [1] SPHERE/ZIMPOL uses extreme adaptive optics to create diffraction-limited images, which come a lot closer than previous adaptive optics instruments to achieving the theoretical limit of the telescope if there were no atmosphere. Extreme adaptive optics also allows much fainter objects to be seen very close to a bright star.

    The images in the new study are also taken in visible light — shorter wavelengths than the near-infrared regime, where most earlier adaptive optics imaging was performed. These two factors result in significantly sharper images than earlier VLT images. Even higher spatial resolution has been achieved with the VLTI, but the interferometer does not create images directly.

    [2] The dust particles must be large enough to ensure the starlight can push it, but not so large that it simply sinks. Too small and the starlight would effectively pass through the dust; too large and the dust would be too heavy to push. The dust the team observed about VY Canis Majoris was precisely the right size to be most effectively propelled outwards by the starlight.

    [3] The explosion will be soon by astronomical standards, but there is no cause for alarm, as this dramatic event is not likely for hundreds of thousands of years. It will be spectacular as seen from Earth — perhaps as bright as the Moon — but not a hazard to life here.
    More information

    This research was presented in a paper entitled Large dust grains in the wind of VY Canis Majoris, by P. Scicluna et al., to appear in the journal Astronomy & Astrophysics.

    The team is composed of P. Scicluna (Academia Sinica Institute for Astronomy and Astrophysics, Taiwan), R. Siebenmorgen (ESO, Garching, Germany), J. Blommaert (Vrije Universiteit, Brussels, Belgium), M. Kasper (ESO, Garching, Germany), N.V. Voshchinnikov (St. Petersburg University, St. Petersburg, Russia), R. Wesson (ESO, Santiago, Chile) and S. Wolf (Kiel University, Kiel, Germany).

    Research paper


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  • richardmitnick 10:23 am on November 15, 2015 Permalink | Reply
    Tags: , , ESO VLT,   

    From Hubble: “Mysterious Ripples Found Racing Through Planet-forming Disk” 

    NASA Hubble Telescope

    Hubble

    Oct. 7, 2015

    Ray Villard
    Space Telescope Science Institute, Baltimore, Maryland
    410-338-4514
    villard@stsci.edu

    Felicia Chou
    NASA Headquarters, Washington, D.C.
    202-358-0257
    felicia.chou@nasa.gov

    Mathias Jäger
    ESA/Hubble, Garching, Germany
    011-49-176-6239-7500
    mjaeger@partner.eso.org

    Anthony Boccaletti
    Paris Observatory, CNRS, Paris, France
    011-33-1-4507-7721
    anthony.boccaletti@obspm.fr

    Glenn Schneider
    Steward Observatory, University of Arizona, Tucson, Arizona
    520-621-5865
    gschneider@as.arizona.edu

    Astronomers using NASA’s Hubble Space Telescope and the European Southern Observatory’s (ESO) Very Large Telescope in Chile have discovered never-before-seen moving features within the dusty disk surrounding the young, nearby star AU Microscopii (AU Mic). The fast-moving, wave-like structures are unlike anything ever observed in a circumstellar disk, said researchers of a new analysis. This new, unexplained phenomenon may provide valuable clues about how planets form inside these star-surrounding disks.

    ESO VLT Interferometer
    ESO/VLT

    1

    AU Mic is located 32 light-years away in the southern constellation Microscopium. It is an optimal star to observe because its circumstellar disk is tilted edge on to our view from Earth. This allows for certain details in the disk to be better seen.

    Astronomers have been searching AU Mic’s disk for any signs of clumpy or warped features that might offer evidence for planet formation. They discovered some very unusual, apparently outward-moving features near the star by using ESO’s SPHERE (Spectro-Polarimetric High-contrast Exoplanet Research) instrument, mounted on the Very Large Telescope.

    ESO SPHERE
    ESO/SPHERE

    “The images from SPHERE show a set of unexplained features in the disk, which have an arc-like, or wave-like structure, unlike anything that has ever been observed before,” said Anthony Boccaletti of the Paris Observatory, the paper’s lead author.

    The images reveal a train of wave-like arches, resembling ripples in water. After spotting the features in the SPHERE data the team turned to earlier Hubble images of the disk, taken in 2010 and 2011. The wave-like nature of some of these features were not recognized in the initial Hubble observations. But once astronomers reprocessed the Hubble images they not only identified the features but realized that they had changed over time. The researchers report that these ripples are moving — and they are moving very fast.

    “We ended up with enough information to track the movement of these strange features over a 3- to 4-year period,” explained team member Christian Thalmann of the Swiss Federal Institute of Technology in Zurich, Switzerland. “By doing this, we found that the arches are racing away from the star at speeds of up to 10 kilometers per second (22,000 miles per hour)!” Co-investigator Carol Grady of Eureka Scientific in Oakland, California, added, “Because nothing like this has been observed or predicted in theory we can only hypothesize when it comes to what we are seeing and how it came about.”

    The ripples farther away from the star seem to be moving faster than those closer to it. At least three of the features are moving so fast that they are likely escaping from the gravitational attraction of the star. Such high speeds rule out the possibility that these features are caused by objects, like planets, gravitationally disturbing material in the disk. The team has also ruled out a series of phenomena as explanations, including the collision of two massive and rare asteroid-like objects releasing large quantities of dust and spiral waves triggered by instabilities in the system’s gravity.

    “One explanation for the strange structure links them to the star’s flares. AU Mic is a star with high flaring activity. This is typical for such young, relatively cool, low-mass stars. AU Mic often lets off huge and sudden bursts of energy from on or near its surface,” said co-author and leader of the Hubble team Glenn Schneider of Steward Observatory in Tucson, Arizona. “One of these flares could perhaps have triggered something on one of the planets — if there are planets — like a violent stripping of material, which could now be propagating through the disk, propelled by the flare’s force.”

    The team plans to continue to observe the AU Mic system to try to understand what is happening. But, for now, these curious features remain an unsolved mystery.

    The results will be published Oct. 8 in the British science journal Nature.
    The international team of astronomers in this study consists of A. Boccaletti (Paris Observatory, CNRS, France), C. Thalmann (ETH Zürich, Switzerland), A.-M. Lagrange (University of Grenoble Alpes, France; CNRS, IPAG, France), M. Janson (Stockholm University; Max Planck Institute for Astronomy), J.-C. Augereau (University of Grenoble Alpes, France; CNRS, IPAG, France), G. Schneider (Steward Observatory, University of Arizona), J. Milli (ESO, Chile; CNRS, IPAG, France), C. Grady (Eureka Scientific), J. Debes (STScI), M. Langlois (CNRS/ENS-L, France), D. Mouillet (University of Grenoble Alpes; CNRS, IPAG, France), T. Henning (Max Planck Institute for Astronomy), C. Dominik (University of Amsterdam), A.-L. Maire (INAF-Observatory of Astronomy, Padova, Italy), J.-L. Beuzit (University of Grenoble Alpes; CNRS, IPAG, France), J. Carson (College of Charleston), K. Dohlen (CNRS, LAM, France), M. Feldt (Max Planck Institute for Astronomy), T. Fusco (ONERA, France; CNRS, LAM, France), C. Ginski (Sterrewacht Leiden, Netherlands), J. Girard (ESO, Chile; CNRS, IPAG, France), D. Hines (STScI), M. Kasper (ESO, Germany; CNRS, IPAG, France), D. Mawet (ESO, Chile), F. Ménard (University of Chile), M. Meyer (ETH Zürich, Switzerland), C. Moutou (CNRS, LAM, France), J. Olofsson (Max Planck Institute for Astronomy), T. Rodigas (Carnegie Institution of Washington), J.-F. Sauvage (ONERA, France; CNRS, LAM, France), J. Schlieder (NASA Ames Research Center; Max Planck Institute for Astronomy), H.M. Schmid (ETH Zürich, Switzerland), M. Turatto (INAF-Observatory of Astronomy, Padova, Italy), S. Udry (Geneva Observatory, Switzerland), F. Vakili (University of Nice-Sophia Antipolis, CNRS, France), A. Vigan (CNRS, LAM, France; ESO, Chile), Z. Wahhaj (ESO, Chile; CNRS, LAM, France) and J. Wisniewski (University of Oklahoma, Norman).

    See the full article here .

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    The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA’s Goddard Space Flight Center manages the telescope. The Space Telescope Science Institute (STScI), is a free-standing science center, located on the campus of The Johns Hopkins University and operated by the Association of Universities for Research in Astronomy (AURA) for NASA, conducts Hubble science operations.

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  • richardmitnick 9:15 am on November 11, 2015 Permalink | Reply
    Tags: , , ESO VLT   

    From ESO: “The Glowing Halo of a Zombie Star” 


    European Southern Observatory

    11 November 2015
    Christopher Manser
    University of Warwick
    United Kingdom
    Email: C.Manser@warwick.ac.uk

    Boris Gänsicke
    University of Warwick
    United Kingdom
    Tel: +44 (0)2476574741
    Email: Boris.Gaensicke@warwick.ac.uk

    Tom Frew
    International Press Officer, University of Warwick
    United Kingdom
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    Cell: +44 (0)7785 433 155
    Email: a.t.frew@warwick.ac.uk

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

    1

    The remains of a fatal interaction between a dead star and its asteroid supper have been studied in detail for the first time by an international team of astronomers using the Very Large Telescope at ESO’s Paranal Observatory in Chile. This gives a glimpse of the far-future fate of the Solar System.

    Led by Christopher Manser, a PhD student at the University of Warwick in the United Kingdom, the team used data from ESO’s Very Large Telescope (VLT) and other observatories to study the shattered remains of an asteroid around a stellar remnant — a white dwarf called SDSS J1228+1040 [1].

    Using several instruments, including the Ultraviolet and Visual Echelle Spectrograph (UVES) and X-shooter, both attached to the VLT, the team obtained detailed observations of the light coming from the white dwarf and its surrounding material over an unprecedented period of twelve years between 2003 and 2015. Observations over periods of years were needed to probe the system from multiple viewpoints [2].

    ESO VLT UVES
    UVES

    ESO X-shooter
    X-shooter

    “The image we get from the processed data shows us that these systems are truly disc-like, and reveals many structures that we cannot detect in a single snapshot,” explained lead author Christopher Manser.

    The team used a technique called Doppler tomography — similar in principle to medical tomographic scans of the human body — which allowed them to map out in detail the structure of the glowing gaseous remains of the dead star’s meal orbiting J1228+1040 for the first time.

    While large stars — those more massive than around ten times the mass of the Sun — suffer a spectacularly violent climax as a supernova explosion at the ends of their lives, smaller stars are spared such dramatic fates. When stars like the Sun come to the ends of their lives they exhaust their fuel, expand as red giants and later expel their outer layers into space. The hot and very dense core of the former star — a white dwarf — is all that remains.

    But would the planets, asteroids and other bodies in such a system survive this trial by fire? What would be left? The new observations help to answer these questions.

    It is rare for white dwarfs to be surrounded by orbiting discs of gaseous material — only seven have ever been found. The team concluded that an asteroid had strayed dangerously close to the dead star and been ripped apart by the immense tidal forces it experienced to form the disc of material that is now visible.

    The orbiting disc was formed in similar ways to the photogenic rings seen around planets closer to home, such as Saturn. However, while J1228+1040 is more than seven times smaller in diameter than the ringed planet, it has a mass over 2500 times greater. The team learned that the distance between the white dwarf and its disc is also quite different — Saturn and its rings could comfortably sit in the gap between them [3].

    The new long-term study with the VLT has now allowed the team to watch the disc precess under the influence of the very strong gravitational field of the white dwarf. They also find that the disc is somewhat lopsided and has not yet become circular.

    “When we discovered this debris disc orbiting the white dwarf back in 2006, we could not have imagined the exquisite details that are now visible in this image, constructed from twelve years of data — it was definitely worth the wait,” added Boris Gänsicke, a co-author of the study.

    Remnants such as J1228+1040 can provide key clues to understanding the environments that exist as stars reach the ends of their lives. This can help astronomers to understand the processes that occur in exoplanetary systems and even forecast the fate of the Solar System when the Sun meets its demise in about seven billion years.

    Notes

    [1] The white dwarf’s full designation is SDSS J122859.93+104032.9.

    [2] The team identified the unmistakable trident-like spectral signature from ionised calcium, called the calcium (Ca II) triplet. The difference between the observed and known wavelengths of these three lines can determine the velocity of the gas with considerable precision.

    [3] Although the disc around this white dwarf is much bigger than Saturn’s ring system in the Solar System, it is tiny compared to the debris discs that form planets around young stars.

    More information

    This research was presented in a paper entitled Doppler-imaging of the planetary debris disc at the white dwarf SDSS J122859.93+104032.9, by C. Manser et al., to appear in the Monthly Notices of the Royal Astronomical Society.

    The team is composed of Christopher Manser (University of Warwick, UK), Boris Gaensicke (University of Warwick), Tom Marsh (University of Warwick), Dimitri Veras (University of Warwick, UK), Detlev Koester (University of Kiel, Germany), Elmé Breedt (University of Warwick), Anna Pala (University of Warwick), Steven Parsons (Universidad de Valparaiso, Chile) and John Southworth (Keele University, UK).

    Link to research paper.
    Photos of the VLT.

    See the full article here .

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  • richardmitnick 5:35 am on October 21, 2015 Permalink | Reply
    Tags: , , ESO VLT, Two stars in collision   

    From ESO: “Final Kiss of Two Stars Heading for Catastrophe” 


    European Southern Observatory

    21 October 2015
    Leonardo Almeida
    Instituto de Astronomia, Geofísica e Ciências Atmosféricas (IAG/USP)
    São Paulo, Brazil
    Tel: +55 011 3091 2818
    Email: leonardodealmeida.andrade@gmail.com

    Hugues Sana
    University of Leuven
    Leuven, Belgium
    Tel: +32 (0) 16 32 19 36
    Email: hugues.sana@kuleuven.be

    Selma de Mink
    University of Amsterdam
    Amsterdam, The Netherlands
    Tel: +31 (0) 6 11 12 15 13
    Email: S.E.deMink@uva.nl

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

    1
    VLT finds hottest and most massive touching double star

    Using ESO’s Very Large Telescope, an international team of astronomers have found the hottest and most massive double star with components so close that they touch each other. The two stars in the extreme system VFTS 352 could be heading for a dramatic end, during which the two stars either coalesce to create a single giant star, or form a binary black hole.

    The double star system VFTS 352 is located about 160 000 light-years away in the Tarantula Nebula [1].

    2
    This first light image of the TRAPPIST national telescope at La Silla shows the Tarantula Nebula, located in the Large Magellanic Cloud (LMC) — one of the galaxies closest to us. Also known as 30 Doradus or NGC 2070, the nebula owes its name to the arrangement of bright patches that somewhat resembles the legs of a tarantula. Taking the name of one of the biggest spiders on Earth is very fitting in view of the gigantic proportions of this celestial nebula — it measures nearly 1000 light-years across! Its proximity, the favourable inclination of the LMC, and the absence of intervening dust make this nebula one of the best laboratories to help understand the formation of massive stars better. The image was made from data obtained through three filters (B, V and R) and the field of view is about 20 arcminutes across.
    Date 8 June 2010
    Source http://www.eso.org/public/images/eso1023a/ (direct link)
    Author TRAPPIST/E. Jehin/ESO

    ESO TRAPPIST telescope
    TRAPPIST national telescope at La Silla

    4
    The Large Magellanic Cloud

    This remarkable region is the most active nursery of new stars in the nearby Universe and new observations from ESO’s VLT [2] have revealed that this pair of young stars is among the most extreme and strangest yet found.

    VFTS 352 is composed of two very hot, bright and massive stars that orbit each other in little more than a day. The centres of the stars are separated by just 12 million kilometres [3]. In fact, the stars are so close that their surfaces overlap and a bridge has formed between them. VFTS 352 is not only the most massive known in this tiny class of overcontact binaries — it has a combined mass of about 57 times that of the Sun — but it also contains the hottest components — with surface temperatures above 40 000 degrees Celsius.

    Extreme stars like the two components of VFTS 352, play a key role in the evolution of galaxies and are thought to be the main producers of elements such as oxygen. Such double stars are also linked to exotic behaviour such as that shown by vampire stars, where a smaller companion star sucks matter from the surface of its larger neighbour (eso1230).

    In the case of VFTS 352, however, both stars in the system are of almost identical size. Material is, therefore, not sucked from one to another, but instead may be shared [4]. The component stars of VFTS 352 are estimated to be sharing about 30 per cent of their material.

    Such a system is very rare because this phase in the life of the stars is short, making it difficult to catch them in the act. Because the stars are so close together, astronomers think that strong tidal forces lead to enhanced mixing of the material in the stellar interiors.

    “The VFTS 352 is the best case yet found for a hot and massive double star that may show this kind of internal mixing,” explains lead author Leonardo A. Almeida of the University of São Paulo, Brazil. “As such it’s a fascinating and important discovery.”

    Astronomers predict that VFTS 352 will face a cataclysmic fate in one of two ways. The first potential outcome is the merging of the two stars, which would likely produce a rapidly rotating, and possibly magnetic, gigantic single star. “If it keeps spinning rapidly it might end its life in one of the most energetic explosions in the Universe, known as a long-duration gamma-ray burst, says the lead scientist of the project, Hugues Sana, of the University of Leuven in Belgium [5].

    The second possibility is explained by the lead theoretical astrophysicist in the team, Selma de Mink of University of Amsterdam: “If the stars are mixed well enough, they both remain compact and the VFTS 352 system may avoid merging. This would lead the objects down a new evolutionary path that is completely different from classic stellar evolution predictions. In the case of VFTS 352, the components would likely end their lives in supernova explosions, forming a close binary system of black holes. Such a remarkable object would be an intense source of gravitational waves.”

    Proving the existence of this second evolutionary path [6] would be an observational breakthrough in the field of stellar astrophysics. But, regardless of how VFTS 352 meets its demise, this system has already provided astronomers with valuable new insights into the poorly understood evolutionary processes of massive overcontact binary star systems.
    Notes

    [1] This star’s name indicates that it was observed as part of the VLT FLAMES Tarantula Survey, which utilised the FLAMES and GIRAFFE instruments on ESO’s Very Large Telescope (VLT) to study over 900 stars in the 30 Doradus region of the Large Magellanic Cloud (LMC). The survey has already led to many exciting and important findings including the fastest rotating star (eso1147), and an extremely massive solitary runaway star (eso1117). It is helping to answer many fundamental questions concerning how massive stars are affected by rotation, binarity and the dynamics in dense star clusters.

    ESO VLT FLAMES
    FLAMES

    ESO VLT GIRAFFE spectrograph
    GIRAFFE

    [2] This study also used brightness measurements of VFTS 352 over a period of twelve years made as part of the OGLE survey.

    [3] Both components are classed as O-type stars. Such stars are typically between 15 and 80 times more massive than the Sun and can be up to a million times brighter. They are so hot that they shine with a brilliant blue-white light and have surface temperatures over 30 000 degrees Celsius.

    [4] These regions around the stars are known as Roche lobes. In an overcontact binary such as VFTS 352 both stars overfill their Roche lobes.

    [5] Gamma-ray Bursts (GRBs) are bursts of highly energetic gamma rays that are detected by orbiting satellites. They come in two types — short duration (shorter than a few seconds), and long duration (longer than a few seconds). Long-duration GRBs are more common and are thought to mark the deaths of massive stars and be associated with a class of very energetic supernova explosions.

    [6] Predicted by [Albert] Einstein’s theory of general relativity, gravitational waves are ripples in the fabric of space and time. Significant gravitational waves are generated whenever there are extreme variations of strong gravitational fields with time, such as during the merger of two black holes.
    More information

    This research was presented in a paper in entitled Discovery of the massive overcontact binary VFTS 352: Evidence for enhanced internal mixing, by L. Almeida et al., in The Astrophysical Journal.

    The team is composed of L.A. Almeida (Johns Hopkins University, Baltimore, Maryland, USA; Instituto de Astronomia, Geofísica e Ciências Atmosféricas, Universidade de São Paulo, Brazil), H. Sana (STScI, Baltimore, Maryland, USA; KU Leuven, Belgium), S.E. de Mink (University of Amsterdam, Netherlands), F. Tramper (University of Amsterdam, Netherlands), I. Soszynski (Warsaw University Observatory, Poland), N. Langer (Universität Bonn, Germany), R.H. Barba (Universidad de La Serena, Chile), M. Cantiello (University of California, Santa Barbara, USA), A. Damineli (Universidade de São Paulo, Brazil), A. de Koter (University of Amsterdam, Netherlands; Universiteit Leuven, Belgium), M. Garcia (Centro de Astrobiologa (INTA-CSIC), Spain), G. Gräfener (Armagh Observatory, UK), A. Herrero (Instituto de Astrofísica de Canarias, Spain; Universidad de La Laguna, Spain), I. Howarth (University College London, UK), J. Maz Apellaniz (Centro de Astrobiologa (INTA-CSIC), Spain), C. Norman (Johns Hopkins University, USA), O.H. Ramrez-Agudelo (University of Amsterdam, Netherlands) and J.S. Vink (Armagh Observatory, UK).

    Links

    Research paper published in The Astrophysical Journal
    Freely accessible preprint of the research paper
    Photos of the VLT [fantastic. Do not miss these.]

    See the full article here .

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  • richardmitnick 6:08 am on October 13, 2015 Permalink | Reply
    Tags: , , , ESO VLT,   

    From AAS NOVA: “A Galaxy Plunges Into a Cluster Core” 

    AASNOVA

    Amercan Astronomical Society

    12 October 2015
    Susanna Kohler

    1

    The galaxy that takes up most of the frame in this stunning image (click for in the full article for the full view!) is NGC 1427A. This is a dwarf irregular galaxy (unlike the fortuitously-located background spiral galaxy in the lower right corner of the image), and it’s currently in the process of plunging into the center of the Fornax https://en.wikipedia.org/wiki/Galaxy_cluster”>galaxy cluster. Marcelo Mora (Pontifical Catholic University, Chile) and collaborators have analyzed observations of this galaxy made by both the [ESO]Very Large Telescope in Chile and the NASA/ESA Hubble Hubble Advanced Camera for Surveys [ACS], which produced the image shown here as a color composite in three channels.

    ESO VLT Interferometer

    NASA Hubble ACS
    ACS on Hubble

    The team worked to characterize the clusters of star formation within NGC 1427A — identifiable in the image as bright knots within the galaxy — and determine how the interactions of this galaxy with its cluster environment affect the star formation within it. For more information and the original image, see the paper below.
    Citation:

    Marcelo D. Mora et al 2015 AJ 150 93. doi:10.1088/0004-6256/150/3/93

    See the full article here.

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