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  • richardmitnick 12:12 pm on December 22, 2015 Permalink | Reply
    Tags: , , , Royal Astronomical Society   

    From RAS: “Giant comets could pose danger to life on Earth” 

    Royal Astronomical Society

    Royal Astronomical Society

    22 December 2015
    Media contacts
    Robert Massey
    Royal Astronomical Society
    Tel: +44 (0)7802 877 699
    rm@ras.org.uk

    Diana Blamires
    University of Buckingham
    diana.blamires@buckingham.ac.uk

    Science contacts
    Dr David Asher
    dja@arm.ac.uk
    Professor Mark Bailey
    meb@arm.ac.uk
    Armagh Observatory
    Northern Ireland
    Tel: +44 (0)28 3752 2928
    http://star.arm.ac.uk

    Professor Bill Napier
    University of Buckingham
    Tel (Ireland): +353 87361 8376
    bill_napier121@hotmail.com

    Professor Duncan Steel
    University of Buckingham
    Tel (New Zealand): +64 4889 0241
    tma1@duncansteel.com

    1
    Because they are so distant from the Earth, Centaurs appear as pinpricks of light in even the largest telescopes. Saturn’s 200-km moon Phoebe, depicted in this image, seems likely to be a Centaur that was captured by that planet’s gravity at some time in the past. Until spacecraft are sent to visit other Centaurs, our best idea of what they look like comes from images like this one, obtained by the Cassini space probe orbiting Saturn. NASA’s New Horizons spacecraft, having flown past Pluto six months ago, has been targeted to conduct an approach to a 45-km wide trans-Neptunian object at the end of 2018. Credit: NASA/JPL-Caltech/Space Science Institute.

    NASA Cassini Spacecraft
    NASA/Cassini

    2
    The outer solar system as we now recognise it. At the centre of the map is the Sun, and close to it the tiny orbits of the terrestrial planets (Mercury, Venus, Earth and Mars). Moving outwards and shown in bright blue are the near-circular paths of the giant planets: Jupiter, Saturn, Uranus and Neptune. The orbit of Pluto is shown in white. Staying perpetually beyond Neptune are the trans-Neptunian objects (TNOs), in yellow: seventeen TNO orbits are shown here, with the total discovered population at present being over 1,500. Shown in red are the orbits of 22 Centaurs (out of about 400 known objects), and these are essentially giant comets (most are 50-100 km in size, but some are several hundred km in diameter). Because the Centaurs cross the paths of the major planets, their orbits are unstable: some will eventually be ejected from the solar system, but others will be thrown onto trajectories bringing them inwards, therefore posing a danger to civilisation and life on Earth. Credit: Duncan Steel.

    A team of astronomers from Armagh Observatory and the University of Buckingham report that the discovery of hundreds of giant comets in the outer planetary system over the last two decades means that these objects pose a much greater hazard to life than asteroids. The team, made up of Professors Bill Napier and Duncan Steel of the University of Buckingham, Professor Mark Bailey of Armagh Observatory, and Dr David Asher, also at Armagh, publish their review of recent research in the December issue of Astronomy & Geophysics (A&G), the journal of the Royal Astronomical Society.

    The giant comets, termed centaurs, move on unstable orbits crossing the paths of the massive outer planets Jupiter, Saturn, Uranus and Neptune. The planetary gravitational fields can occasionally deflect these objects in towards the Earth.

    Centaurs are typically 50 to 100 kilometres across, or larger, and a single such body contains more mass than the entire population of Earth-crossing asteroids found to date. Calculations of the rate at which centaurs enter the inner solar system indicate that one will be deflected onto a path crossing the Earth’s orbit about once every 40,000 to 100,000 years. Whilst in near-Earth space they are expected to disintegrate into dust and larger fragments, flooding the inner solar system with cometary debris and making impacts on our planet inevitable.

    Known severe upsets of the terrestrial environment and interruptions in the progress of ancient civilisations, together with our growing knowledge of interplanetary matter in near-Earth space, indicate the arrival of a centaur around 30,000 years ago. This giant comet would have strewn the inner planetary system with debris ranging in size from dust all the way up to lumps several kilometres across.

    Specific episodes of environmental upheaval around 10,800 BCE and 2,300 BCE, identified by geologists and palaeontologists, are also consistent with this new understanding of cometary populations. Some of the greatest mass extinctions in the distant past, for example the death of the dinosaurs 65 million years ago, may similarly be associated with this giant comet hypothesis.

    Professor Napier comments: “In the last three decades we have invested a lot of effort in tracking and analysing the risk of a collision between the Earth and an asteroid. Our work suggests we need to look beyond our immediate neighbourhood too, and look out beyond the orbit of Jupiter to find centaurs. If we are right, then these distant comets could be a serious hazard, and it’s time to understand them better.”

    The researchers have also uncovered evidence from disparate fields of science in support of their model. For example, the ages of the sub-millimetre craters identified in lunar rocks returned in the Apollo program are almost all younger than 30,000 years, indicating a vast enhancement in the amount of dust in the inner Solar system since then.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    The Royal Astronomical Society (RAS), founded in 1820, encourages and promotes the study of astronomy, solar-system science, geophysics and closely related branches of science.

     
  • richardmitnick 9:59 pm on December 3, 2015 Permalink | Reply
    Tags: , , CW Leo, Royal Astronomical Society   

    From RAS: “Curious “Inkblot” star outed for trolling the astronomers” 

    Royal Astronomical Society

    Royal Astronomical Society

    03 December 2015
    Media contacts
    Vivienne Reiner
    University of Sydney Media and PR Adviser
    Tel: + 61 2 9351 2390
    Mob: +61 438 021 390
    vivienne.reiner@sydney.edu.au

    Robert Massey
    Royal Astronomical Society
    Tel: +44 (0)20 7734 3307
    Mob: +44 (0)7802 877 699
    rm@ras.org.uk

    Science contacts
    Paul Stewart
    The University of Sydney
    p.stewart@physics.usyd.edu.au

    Prof Peter Tuthill
    The University of Sydney
    Tel: +61 2 9351 3679
    p.tuthill@physics.usyd.edu.au

    1
    Animation showing the changes in the dying star CW Leo as it expels tremendous volumes of thick dust into the surrounding nebula over the course of almost a decade. The bright knot in the lower left has long been believed to be the star itself, however we see that over a short space of time it appears to move over 4 billion kilometers from this initial stable position, something a star simply cannot do. Instead what we see is hot spots in the clouds of stardust, whilst the star itself must be completely buried inside the turbulent nebula. Credit: Paul Stewart

    New images of an intriguing red giant star, known as CW Leo, have turned the usual astronomy narrative on its head, with scrutiny focussed not only on the stars but also on the astronomers who study them. In just a couple of years, the 400 light year distant CW Leo has changed its appearance completely, meaning a whole set of carefully constructed models have been abandoned. The researchers, led by Paul Stewart of the University of Sydney, publish their results today in Monthly Notices of the Royal Astronomical Society.

    Stars like our Sun become red giants near the end of their lives, after most of their available hydrogen fuel has been consumed. These huge objects – tens of times the size of our star – will eventually eject most of their atmosphere into space and create a planetary nebula, leaving behind a hot core that cools down over billions of years. CW Leo is nearing the end of its red giant stage and starting to throw out large amounts of matter.

    “Although it is invisible to our eyes, to astronomers CW Leo is one of the most famous stars in the sky.” explains Stewart. “If we could see infrared light, it would be by far the brightest star in the sky. However the real excitement here is the extreme physics – it is a swollen luminous giant poised at the most self-destructive phase of its existence. It is literally tearing itself apart under its own glare, hurling dense clouds of dust and gas out into the galaxy; dying amidst its own glorious final fireworks display.”

    2
    A panel of images showing the turbulent clouds of stardust enveloping and concealing CW Leo. In the space of a few years these tore apart a seemingly stable configuration to reveal an entirely new face. Reconstructed from interferometric observations obtained at observatories with some of the largest telescopes in the world including Keck and the VLT, as well as from stellar occultations by the rings of Saturn observed with the Cassini spacecraft. Credit: Paul Stewart.

    The team of astronomers used images from the Keck and VLT telescopes, and the Cassini space probe, to study CW Leo over more than a decade.

    Keck Observatory
    Keck

    ESO VLT Interferometer
    ESO/VLT

    NASA Cassini Spacecraft
    NASA/Cassini

    As might be expected from such a roiling cauldron of heat and dust, the star’s appearance evolves, but in the past this has been quite a stately affair. However the new images catch something more dramatic – in the last couple of years, it completely shedded its familiar identity and adopted an entirely new visage. Such behaviour is a serious problem for the astronomers who have spent the decades studying this unique system.

    “This is one of those humble moments when nature reminds us all who is boss.” reflects Prof Peter Tuthill, co-author on the work. “For the last 20 years many astronomers – and I count as one – have tried to put a skeleton underneath the clumpy images we see. I have seen complex models mathematically carving the nebula around the star up into cavities, plumes, and disks and halos. However, all along the star had decidedly other ideas.”

    “The big problem with all the models is the scaffolding that they tried to impose onto the system” explains Stewart. “When all the structures we thought we knew can completely melt away to be quickly replaced by new ones, then what are we left with?”

    “It is pretty clear that the new images tell us is that CW Leo has just been ejecting clumps and plumes of hot dust at random all this time.” agrees Tuthill. “It is like a celestial version of the famous Rorschach Ink Blot Test in psychology. In trying to find underlying structure to the clumps and blobs, we have seen little more than our own preconceptions reflected back at us. Seeing rabbits or elephants in the clouds is okay for my 4-year old boy, but it seems that this time a dusty star in Leo has caught all the astronomers out daydreaming at their work.”

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    The Royal Astronomical Society (RAS), founded in 1820, encourages and promotes the study of astronomy, solar-system science, geophysics and closely related branches of science.

     
  • richardmitnick 2:37 pm on October 10, 2015 Permalink | Reply
    Tags: , , Royal Astronomical Society,   

    From RAS: “Universe’s hidden supermassive black holes revealed” From July but Well Worth Your Time 

    Royal Astronomical Society

    Royal Astronomical Society

    09 July 2015
    Dr Robert Massey
    Royal Astronomical Society
    Mob: +44 (0)794 124 8035
    rm@ras.org.uk

    Ms Anita Heward
    Royal Astronomical Society
    Mob: +44 (0)7756 034 243
    anitaheward@btinternet.com

    Dr Sam Lindsay
    Royal Astronomical Society
    Mob: +44 (0)7957 566 861
    sl@ras.org.uk

    Durham University Marketing and Communications Office
    Tel: +44 (0)191 334 6075
    communications.team@durham.ac.uk

    Astronomers have found evidence for a large population of hidden supermassive black holes in the Universe. Using NASA’s Nuclear Spectroscopic Telescope Array (NuSTAR) satellite observatory, the team of international scientists detected the high-energy x-rays from five supermassive black holes previously clouded from direct view by dust and gas. The findings were presented today at the Royal Astronomical Society’s National Astronomy Meeting, at Venue Cymru, in Llandudno, Wales (Monday 6 July).

    1
    NASA/Nu-STAR Credit: NASA/JPL-Caltech.

    The research, led by astronomers at Durham University, UK, supports the theory that potentially millions more supermassive black holes exist in the Universe, but are hidden from view.

    The scientists pointed NuSTAR at nine candidate hidden supermassive black holes that were thought to be extremely active at the centre of galaxies, but where the full extent of this activity was potentially obscured from view.

    High-energy x-rays found for five of the black holes confirmed that they had been hidden by dust and gas. The five were much brighter and more active than previously thought as they rapidly feasted on surrounding material and emitted large amounts of radiation.

    3
    A Hubble Space Telescope colour image of one of the nine galaxies targeted by NuSTAR. The high energy X-rays detected by NuSTAR revealed the presence of an extremely active supermassive black hole at the galaxy centre, deeply buried under a blanket of gas and dust. Credit: Hubble Legacy Archive, NASA, ESA.

    NASA Hubble Telescope
    NASA/ESA Hubble

    Such observations were not possible before NuSTAR, which launched in 2012 and is able to detect much higher energy x-rays than previous satellite observatories.

    Lead author George Lansbury, a postgraduate student in the Centre for Extragalactic Astronomy, at Durham University, said: “For a long time we have known about supermassive black holes that are not obscured by dust and gas, but we suspected that many more were hidden from our view.

    “Thanks to NuSTAR for the first time we have been able to clearly see these hidden monsters that are predicted to be there, but have previously been elusive because of their ‘buried’ state.

    “Although we have only detected five of these hidden supermassive black holes, when we extrapolate our results across the whole Universe then the predicted numbers are huge and in agreement with what we would expect to see.”

    Daniel Stern, the project scientist for NuSTAR at NASA’s Jet Propulsion Laboratory in Pasadena, California, added: “High-energy X-rays are more penetrating than low-energy X-rays, so we can see deeper into the gas burying the black holes. NuSTAR allows us to see how big the hidden monsters are and is helping us learn why only some black holes appear obscured.”

    The research was funded by the Science and Technology Facilities Council (STFC) and has been accepted for publication in The Astrophysical Journal.

    4
    An artist’s illustration of a supermassive black hole, actively feasting on its surroundings. The central black hole is hidden from direct view by a thick layer of encircling gas and dust.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    The Royal Astronomical Society (RAS), founded in 1820, encourages and promotes the study of astronomy, solar-system science, geophysics and closely related branches of science.

     
  • richardmitnick 8:44 am on September 14, 2015 Permalink | Reply
    Tags: , , , Royal Astronomical Society   

    From RAS: “Astronomers peer into the ‘amniotic sac’ of a planet-hosting star” 

    Royal Astronomical Society

    Royal Astronomical Society

    14 September 2015
    Media contact
    Sarah Reed
    University of Leeds
    Tel: +44 (0)113 343 4196
    s.j.reed@leeds.ac.uk

    Science contacts
    Dr Ignacio Mendigutía
    University of Leeds
    Tel: +44(0)113 34 33871
    I.Mendigutia@leeds.ac.uk

    Professor Rene Oudmaijer
    University of Leeds
    Tel: +44 (0)113 34 33886
    roud@ast.leeds.ac.uk

    1
    This image from the NASA/ESA Hubble Space Telescope shows a visible light view of the outer dust around the young star HD 100546. The position of the newly discovered protoplanet is marked with an orange spot. The inner part of this picture is dominated by artifacts from the brilliant central star, which has been digitally subtracted, and the black blobs are not real.
    Date 28 February 2013, 16:00:00
    Source http://www.eso.org/public/images/eso1310d/
    Author ESO/NASA/ESA/Ardila et al.

    NASA Hubble Telescope
    NASA/ESA Hubble

    Astronomers have successfully peered through the ‘amniotic sac’ of a star that is still forming to observe the innermost region of a burgeoning solar system for the first time.

    In a research paper published today in the journal Monthly Notices of the Royal Astronomical Society, an international team of astronomers describe surprising findings in their observations of the parent star, which is called HD 100546.

    Lead author Dr Ignacio Mendigutía, from the School of Physics and Astronomy at the University of Leeds, said: “Nobody has ever been able to probe this close to a star that is still forming and which also has at least one planet so close in.

    “We have been able to detect for the first time emission from the innermost part of the disk of gas that surrounds the central star. Unexpectedly, this emission is similar to that of ‘barren’ young stars that do not show any signs of active planet formation.”

    To observe this distant system, the astronomers used the [ESO] Very Large Telescope Interferometer (VLTI), which is based in an observatory in Chile. The VLTI combines the observing power of four 8.2m-wide telescopes and can make images as sharp as that of a single telescope that is 130m in diameter.

    ESOVLTI
    ESO VLTI MIDI
    ESO VLTI

    Professor Rene Oudmaijer, a co-author of the study, also from the University’s School of Physics and Astronomy, said: “Considering the large distance that separates us from the star (325 light-years), the challenge was similar to trying to observe something the size of a pinhead from 100km away.”

    HD 100546 is a young star (only a thousandth of the age of the Sun) surrounded by a disk-shaped structure of gas and dust, called a ‘proto-planetary disk‘, in which planets can form. Such disks are common around young stars, but the one around HD 100546 is very peculiar: if the star were placed at the centre of our Solar System, the outer part of the disk would extend up to around ten times the orbit of Pluto.

    Dr Mendigutía said: “More interestingly, the disk exhibits a gap that is devoid of material. This gap is very large, about 10 times the size of the space that separates the Sun from the Earth. The inner disk of gas could only survive for a few years before being trapped by the central star, so it must be continuously replenished somehow.

    “We suggest that the gravitational influence of the still-forming planet – or possibly planets – in the gap could be boosting a transfer of material from the gas-rich outer part of the disk to the inner regions.”

    Systems such as HD 100546 which are known to have both a planet and a gap in the proto-planetary disk are extremely rare. The only other example that has been reported is of a system in which the gap in the disk is ten times further out from the parent star than the one in the new study.

    “With our observations of the inner disk of gas in the HD 100546 system, we are beginning to understand the earliest life of planet-hosting stars on a scale that is comparable to our Solar System,” concludes Professor Oudmaijer.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    The Royal Astronomical Society (RAS), founded in 1820, encourages and promotes the study of astronomy, solar-system science, geophysics and closely related branches of science.

     
  • richardmitnick 11:26 am on August 26, 2015 Permalink | Reply
    Tags: , , Royal Astronomical Society   

    From RAS: “Celestial firework marks nearest galaxy collision” 

    Royal Astronomical Society

    Royal Astronomical Society

    14 August 2015
    Media contacts
    Dr Sam Lindsay
    Royal Astronomical Society
    Tel: +44 (0)2077 344 582
    sl@ras.org.uk

    Dr Morgan Hollis
    Royal Astronomical Society
    Tel: +44 (0)2077 344 582
    mh@ras.org.uk

    Dr Sheila Kanani
    Royal Astronomical Society
    Mob: +44 (0)7802 877 698
    sk@ras.org.uk

    Science contacts
    Prof Quentin Parker
    University of Hong Kong
    Hong Kong
    Tel: +27 (0)791 900 475
    quentinp@hku.hk

    Prof Albert Zijlstra
    University of Manchester
    UK
    Tel: +44 (0)7780 747 869
    a.zijlstra@manchester.ac.uk

    1
    Colour image of the collision, made by combining the CTIO H-alpha image with red and blue images. Credit: Ivan Bojicic / the scientific team.

    CTIO Victor M Blanco 4m Telescope
    CTIO Victor M Blanco 4m Telescope interior
    http://www.ctio.noao.edu/noao/content/Victor-Blanco-4-m-Telescope

    2
    Residual image of the collision, made by subtracting the red image from the CTIO H-alpha image, which mostly cancels the contributions from normal stars and is effective in highlighting just the areas of active star formation. Credit: Quentin Parker / the scientific team.

      A spectacular galaxy collision has been discovered lurking behind the Milky Way. The closest such system ever found, the discovery was announced today by a team of astronomers led by Prof. Quentin Parker at the University of Hong-Kong and Prof. Albert Zijlstra at the University of Manchester. The scientists publish their results in Monthly Notices of the Royal Astronomical Society.

      The galaxy is 30 million light years away, which means that it is relatively close by. It has been dubbed “Kathryn’s Wheel” both after the famous firework that it resembles, but also after the wife of the paper’s second author.

      Such systems are very rare and arise from “bulls-eye” collisions between two galaxies of similar mass. Shockwaves from the collision compress reservoirs of gas in each galaxy and trigger the formation of new stars. This creates a spectacular ring of intense emission, and lights up the system like a Catherine wheel firework on bonfire night.

      Galaxies grow through collisions but it is rare to catch one in the process, and extremely rare to see a bull’s-eye collision in progress. Fewer than 20 systems with complete rings are known.

      Kathryn’s Wheel was discovered during a special wide field survey of the Southern Milky Way undertaken with the UK Schmidt Telescope in Australia.

      UK Schmidt Telescope Exterior
      UK Schmidt Telescope Interior
      UK Schmidt telescope

      It used a narrow wavelength optical region centred on the so-called red “H-alpha” emission line of gaseous hydrogen. This rare jewel was uncovered during a search of the survey images for the remnants of dying stars in our Milky Way. The authors were very surprised to also find this spectacular cosmic ring, sitting remotely behind the dust and gas of the Milky Way in the constellation of Ara (the Altar).

      The newly discovered ring galaxy is seven times closer than anything similar found before, and forty times closer than the famous ‘Cartwheel’ galaxy.

      3
      This image shows the Cartwheel Galaxy as seen from Hubble Space Telescope.

      NASA Hubble Telescope
      NASA/ESA Hubble

      The ring is located behind a dense star field and close to a very bright foreground star, which is why it had not been noted before. There are very few other galaxies in its neighbourhood; the odds of a collision in such an empty region of space are very low.

      Professor Parker said “Not only is this system visually stunning, but it’s close enough to be an ideal target for detailed study. The ring is also quite low in mass – a few thousand million Suns, or less than 1% of the Milky Way – so our discovery shows that collision rings can form around much smaller galaxies than we thought.”

      Professor Zijlstra added “It is not often that you get to name any objects in the sky. But I think Kathryn’s Wheel is particularly fitting, resembling as it does a firework and continuing the tradition of naming objects after loved ones.”

      Smaller galaxies are more common than large ones, implying that collisional rings could be ten times as common as previously thought. The authors intend to carry out more detailed studies on larger telescopes since the discovered galaxy is currently the only one of its kind close enough to permit study in such exquisite detail.

      See the full article here.

      Please help promote STEM in your local schools.

      STEM Icon

      Stem Education Coalition

      The Royal Astronomical Society (RAS), founded in 1820, encourages and promotes the study of astronomy, solar-system science, geophysics and closely related branches of science.

     
    • richardmitnick 10:37 am on August 27, 2015 Permalink | Reply

      While CTIO was referenced in the captions to graphics, the CTIO instrument used was not credited. I emailed the witer to complain. He came back and told me it was the Victor M Blanco 4 meter telescope. I modiifed the post to include the telescope.

      Like

  • richardmitnick 4:47 pm on August 17, 2015 Permalink | Reply
    Tags: , , Royal Astronomical Society   

    From RAS: “Celestial firework marks nearest galaxy collision” 

    Royal Astronomical Society

    Royal Astronomical Society

    16 August 2015
    Media contacts
    Dr Sam Lindsay
    Royal Astronomical Society
    Tel: +44 (0)2077 344 582
    sl@ras.org.uk
    Dr Morgan Hollis
    Royal Astronomical Society
    Tel: +44 (0)2077 344 582
    mh@ras.org.uk
    Dr Sheila Kanani
    Royal Astronomical Society
    Mob: +44 (0)7802 877 698
    sk@ras.org.uk

    Science contacts
    Prof Quentin Parker
    University of Hong Kong
    Hong Kong
    Tel: +27 (0)791 900 475
    quentinp@hku.hk
    Prof Albert Zijlstra
    University of Manchester
    UK
    Tel: +44 (0)7780 747 869
    a.zijlstra@manchester.ac.uk

    1
    Researchers created this image highlighting areas of active star formation in the newly-discovered collisional ring galaxy called “Kathryn’s Wheel.”
    Quentin Parker/the scientific team

    2
    PHOTO: Researchers captured an image of a newly-discovered collisional ring galaxy called “Kathryn’s Wheel” using the CTIO telescope* in Chile.

    Above two images from ABC News, USA

    A spectacular galaxy collision has been discovered lurking behind the Milky Way. The closest such system ever found, the discovery was announced today by a team of astronomers led by Prof. Quentin Parker at the University of Hong-Kong and Prof. Albert Zijlstra at the University of Manchester. The scientists publish their results in Monthly Notices of the Royal Astronomical Society.

    The galaxy is 30 million light years away, which means that it is relatively close by. It has been dubbed “Kathryn’s Wheel” both after the famous firework that it resembles, but also after the wife of the paper’s second author.

    Such systems are very rare and arise from “bulls-eye” collisions between two galaxies of similar mass. Shockwaves from the collision compress reservoirs of gas in each galaxy and trigger the formation of new stars. This creates a spectacular ring of intense emission, and lights up the system like a Catherine wheel firework on bonfire night.

    Galaxies grow through collisions but it is rare to catch one in the process, and extremely rare to see a bull’s-eye collision in progress. Fewer than 20 systems with complete rings are known.

    Kathryn’s Wheel was discovered during a special wide field survey of the Southern Milky Way undertaken with the UK Schmidt Telescope in Australia.

    UK Schmidt Telescope Exterior
    UK Schmidt Telescope Interior
    UK Schmidt Telescope

    It used a narrow wavelength optical region centred on the so-called red “H-alpha” emission line of gaseous hydrogen. This rare jewel was uncovered during a search of the survey images for the remnants of dying stars in our Milky Way. The authors were very surprised to also find this spectacular cosmic ring, sitting remotely behind the dust and gas of the Milky Way in the constellation of Ara (the Altar).

    The newly discovered ring galaxy is seven times closer than anything similar found before, and forty times closer than the famous ‘Cartwheel’ galaxy. The ring is located behind a dense star field and close to a very bright foreground star, which is why it had not been noted before. There are very few other galaxies in its neighbourhood; the odds of a collision in such an empty region of space are very low.

    Professor Parker said “Not only is this system visually stunning, but it’s close enough to be an ideal target for detailed study. The ring is also quite low in mass – a few thousand million Suns, or less than 1% of the Milky Way – so our discovery shows that collision rings can form around much smaller galaxies than we thought.”

    Professor Zijlstra added “It is not often that you get to name any objects in the sky. But I think Kathryn’s Wheel is particularly fitting, resembling as it does a firework and continuing the tradition of naming objects after loved ones.”

    Smaller galaxies are more common than large ones, implying that collisional rings could be ten times as common as previously thought. The authors intend to carry out more detailed studies on larger telescopes since the discovered galaxy is currently the only one of its kind close enough to permit study in such exquisite detail.

    • Which telescope among the many is not told to us.

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    The Royal Astronomical Society (RAS), founded in 1820, encourages and promotes the study of astronomy, solar-system science, geophysics and closely related branches of science.

     
  • richardmitnick 8:14 pm on August 4, 2015 Permalink | Reply
    Tags: , , , Royal Astronomical Society   

    From RAS: “5 billion light years across: the largest feature in the universe” 

    Royal Astronomical Society

    Royal Astronomical Society

    04 August 2015

    Media contact
    Dr Robert Massey
    Royal Astronomical Society
    Tel: +44 (0)20 7734 3307
    Mob: +44 (0)794 124 8035
    rm@ras.org.uk

    Science contact
    rof Lajos Balazs
    Konkoly Observatory
    Budapest
    Hungary
    Tel: +36 1 3919354
    lgbalazs@gmail.com

    1
    An image of the distribution of GRBs on the sky at a distance of 7 billion light years, centred on the newly discovered ring. The positions of the GRBs are marked by blue dots and the Milky Way is indicated for reference, running from left to right across the image. Credit: L. Balazs.

    A Hungarian-US team of astronomers have found what appears to be the largest feature in the observable universe: a ring of nine gamma ray bursts [GRB’S] – and hence galaxies – 5 billion light years across. The scientists, led by Prof Lajos Balazs of Konkoly Observatory in Budapest, report their work in a paper in Monthly Notices of the Royal Astronomical Society.

    Gamma-ray bursts (GRBs) are the most luminous events in the universe, releasing as much energy in a few seconds as the Sun does over its 10 billion year lifetime. They are thought to be the result of massive stars collapsing into black holes. Their huge luminosity helps astronomers to map out the location of distant galaxies, something the team exploited.

    The GRBs that make up the newly discovered ring were observed using a variety of space- and ground-based observatories (the sample is listed in the Gamma Ray Burst Online Index). They appear to be at very similar distances from us – around 7 billion light years – in a circle 36° across on the sky, or more than 70 times the diameter of the Full Moon. This implies that the ring is more than 5 billion light years across, and according to Prof Balazs there is only a 1 in 20,000 probability of the GRBs being in this distribution by chance.

    Most current models indicate that the structure of the cosmos is uniform on the largest scales. This ‘Cosmological Principle’ is backed up by observations of the early universe and its microwave background signature, seen by the WMAP and Planck satellites.

    Cosmic Microwave Background WMAP
    CMB per NASA/WMAP

    NASA WMAP
    NASA/WMAP

    Cosmic Background Radiation Planck
    CMB per ESA/Planck

    ESA Planck
    ESA/Planck

    Other recent results and this new discovery challenge the principle, which sets a theoretical limit of 1.2 billion light years for the largest structures. The newly discovered ring is almost five times as large.

    “If the ring represents a real spatial structure, then it has to be seen nearly face-on because of the small variations of GRB distances around the object’s centre. The ring could though instead be a projection of a sphere, where the GRBs all occurred within a 250 million year period, a short timescale compared with the age of the universe.”

    A spheroidal ring projection would mirror the strings of clusters of galaxies seen to surround voids in the universe; voids and string-like formations are seen and predicted by many models of the cosmos. The newly discovered ring is however at least ten times larger than known voids.

    Prof Balazs comments: “If we are right, this structure contradicts the current models of the universe. It was a huge surprise to find something this big – and we still don’t quite understand how it came to exist at all.”

    The team now want to find out more about the ring, and establish whether the known processes for galaxy formation and large scale structure could have led to its creation, or if astronomers need to radically revise their theories of the evolution of the cosmos.

    Further information

    The new work appears in A giant ring-like structure at 0.78 < z < 0.86 displayed by GRBs, Monthly Notices of the Royal Astronomical Society, L. G. Balazs, Z. Bagoly, J. E. Hakkila I. Horvath, J. Kobori, I. R ́acz and L. V. T ́oth, Oxford University Press.

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

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    The Royal Astronomical Society (RAS), founded in 1820, encourages and promotes the study of astronomy, solar-system science, geophysics and closely related branches of science.

     
  • richardmitnick 8:07 am on July 23, 2015 Permalink | Reply
    Tags: , , , Royal Astronomical Society   

    From RAS: “Treasure hunting in archive data reveals clues about black holes’ diet” 

    Royal Astronomical Society

    Royal Astronomical Society

    23 July 2015

    Media contact
    Dr Hannelore Hämmerle
    Pressesprecherin
    Max-Planck-Institut für extraterrestrische Physik
    Garching
    Germany
    Tel: +49 (0)89 30000 3980
    pr@mpe.mpg.de

    Science contact
    Dr Andrea Merloni
    Max-Planck-Institut für extraterrestrische Physik
    Garching
    Germany
    Tel: +49 (0)89 30000-3893
    am@mpe.mpg.de

    1
    A snapshot image from a computer simulation of a star disrupted by a supermassive black hole. The red-orange plumes show the debris of the star after its passage near the black hole (located close to the bottom left corner of the image). About half of the disrupted star moves in elliptical orbits around the black hole and forms an accretion disc which eventually shines brightly in optical and X-ray wavelengths. Credit: J. Guillochon (Harvard University) and E. Ramirez-Ruiz (University of California).

    Using archival data from the Sloan Digital Sky Survey [SDSS], and the XMM-Newton and Chandra X-ray telescopes, a team of astronomers have discovered a gigantic black hole, which is probably destroying and devouring a massive star in its vicinity.

    Sloan Digital Sky Survey Telescope
    SDSS telescope at Apache Point, NM, USA

    ESA XMM Newton
    ESA/XMM-Newton

    NASA Chandra Telescope
    NASA/Chandra

    With a mass of 100 million times more than our Sun, this is the largest black hole caught in this act so far. The results of this study are published in a paper in the journal Monthly Notices of the Royal Astronomical Society.

    Andrea Merloni and members of his team, from the Max-Planck Institute for Extraterrestrial Physics (MPE) in Garching, near Munich, were exploring the huge archive of the Sloan Digital Sky Survey (SDSS) in preparation for a future X-ray satellite mission. The SDSS has been observing a large fraction of the night sky with its optical telescope. In addition, spectra (where light is dispersed across wavelengths, allowing astronomers to deduce properties like composition and temperature) have been taken of distant galaxies and black holes.

    2
    These plots show two SDSS spectra of the object; the different luminosities as a function of wavelength between the two epochs are clearly visible. In particular, the red dashed vertical lines show the hydrogen Balmer lines which dramatically change their shape: in the red spectrum they are much broader, which provides a “fingerprint” signature of the accretion onto a central black hole. Credit: © SDSS/MPE.

    For a variety of reasons, the spectra of some objects were taken more than once. And when the team was looking at one of the objects with multiple spectra, they were struck by an extraordinary change in one of the objects under study, with the catalogue number SDSS J0159+0033, a galaxy in the constellation of Cetus. The huge distance to the galaxy means that we see it as it was 3.5 billion years ago.

    “Usually distant galaxies do not change significantly over an astronomer’s lifetime, i.e. on a timescale of years or decades,” explains Andrea Merloni, “but this one showed a dramatic variation of its spectrum, as if the central black hole had switched on and off.”

    This happened between 1998 and 2005, but nobody had noticed the odd behaviour of this galaxy until late last year, when two groups of scientists preparing the next (fourth) generation of SDSS surveys independently stumbled across these data.

    Luckily enough, the two flagship X-ray observatories, the ESA-led XMM-Newton and the NASA-led Chandra took snapshots of the same area of the sky close in time to the peak of the flare, and again about ten years later. This gave the astronomers unique information about the high-energy emission that reveals how material is processed in the immediate vicinity of the central black hole.

    Gigantic black holes are at home in the nuclei of large galaxies all around us. Most astronomers believe that they grew to the enormous sizes that we can observe today by feeding mostly on interstellar gas from their surroundings, which is unable to escape the immense gravitational pull. Such a process takes place over a very long time (tens to hundreds of millions of years), and is capable of turning a small black hole created in the explosion of a heavy star into the super-heavyweight monsters that lurk at the centre of galaxies.

    However, galaxies also contain a huge number of stars. Some unlucky ones may happen to pass too close to the central black hole, where they are destroyed and eventually swallowed by the black hole. If this is compact enough, the strong, tidal gravitational forces tear the star apart in a spectacular way. Subsequently bits and pieces swirl into the black hole and thus produce huge flares of radiation that can be as luminous as all of the rest of the stars in the host galaxy for a period of a few months to a year. These rare events are called Tidal Disruption Flares (TDF).

    Merloni and his collaborators quite quickly realised that ‘their’ flare matched almost perfectly all the expectations of this model. Moreover, because of the serendipitous nature of the discovery, they realised that this was an even more peculiar system than those which had been found through active searches until now. With an estimated mass of 100 million solar masses, this is the biggest black hole caught in the act of star-tearing so far.

    However, the sheer size of the system is not the only intriguing aspect of this particular flare; it is also the first one for which scientists can assume with some degree of certainty that the black hole was on a more standard ‘gas diet’ very recently (a few tens of thousands of years). This is an important clue to finding out which sort of food black holes mostly live on.


    Download video here: https://www.youtube.com/watch?feature=player_embedded&v=hggUYcmSjlI
    This computer simulation of the disruption of a star by a black hole shows the formation of an accretion disk of stellar material spiralling into the black hole. This sequence shows an early stage in the formation of the disk. The stellar material is coloured according to its temperature, with red being colder and purple hotter. Credit: J. Guillochon and E. Ramirez Ruiz

    “Louis Pasteur said: ‘Chance favours the prepared mind’ – but in our case, nobody was really prepared,” marvels Merloni. “We could have discovered this unique object already ten years ago, but people did not know where to look. It is quite common in astronomy that progress in our understanding of the cosmos is helped by serendipitous discoveries. And now we have a better idea of how to find more such events, and future instruments will greatly expand our reach.”

    In less than two years’ time a new powerful X-ray telescope eROSITA, which is currently being built at MPE, will be put into orbit on the Russian-German SRG satellite.

    MPE eROSETTA
    eROSITA

    It will scan the entire sky with the right cadence and sensitivity needed to discover hundreds of new tidal disruption flares. Big optical telescopes are also being designed and built with the goal of monitoring the variable sky, and will greatly contribute to solving the mystery of black hole eating habits. Astronomers will have to be prepared to catch these dramatic last acts of a star’s life. But however prepared they’ll be, the sky will be full of new surprises.

    Further information

    The new work appears in A tidal disruption flare in a massive galaxy? Implications for the fuelling mechanisms of nuclear black holes, A. Merloni, T. Dwelly, M. Salvato, A. Georgakakis, J. Greiner, M. Krumpe, K. Nandra, G. Ponti, A. Rau, Monthly Notices of the Royal Astronomical Society, Oxford University Press.
    The other group, who independently discovered the strange light curve of this object, was Stephanie Lamassa (Yale) and her collaborators. They were the fastest to alert the community about this object, but did not explore the stellar disruption interpretation for this event.
    Tidal Disruption Flares are very rare, with perhaps one occurring every few tens of thousands of year in any given galaxy. In addition, because they do not last very long, they are very hard to find. Only about twenty of them have been studied so far, but with the advent of larger telescopes designed to survey large areas of the sky in a short time, more and more dedicated searches are being carried out, and the pace of discovery is rapidly increasing.

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    The Royal Astronomical Society (RAS), founded in 1820, encourages and promotes the study of astronomy, solar-system science, geophysics and closely related branches of science.

     
  • richardmitnick 9:01 am on July 8, 2015 Permalink | Reply
    Tags: , , Royal Astronomical Society, ,   

    From RAS: “Searing Sun seen in X-rays” 

    Royal Astronomical Society

    Royal Astronomical Society

    08 July 2015
    Media contacts

    Dr Robert Massey
    Royal Astronomical Society
    Mob: +44 (0)794 124 8035
    rm@ras.org.uk

    Ms Anita Heward
    Royal Astronomical Society
    Mob: +44 (0)7756 034 243
    anitaheward@btinternet.com

    Dr Sam Lindsay
    Royal Astronomical Society
    Mob: +44 (0)7957 566 861
    sl@ras.org.uk

    Whitney Clavin
    Jet Propulsion Laboratory, Pasadena, California
    818-354-4673
    whitney.clavin@jpl.nasa.gov

    Science contacts

    Dr Iain Hannah
    Royal Society Research Fellow,
    Astronomy & Astrophysics Group
    University of Glasgow
    iain.hannah@glasgow.ac.uk

    1
    Flaring, active regions of our Sun are highlighted in this new image combining observations from several telescopes. Credit: NASA/JPL-Caltech/GSFC/JAXA.

    X-rays light up the surface of our Sun in a bouquet of colours in this new image containing data from NASA’s Nuclear Spectroscopic Telescope Array, or NuSTAR.

    NASA NuSTAR
    NASA/NuSTAR

    The high-energy X-rays seen by NuSTAR are shown in blue, while green represents lower-energy X-rays from the X-ray Telescope instrument on the Hinode spacecraft, named after the Japanese word for sunrise. The yellow and green colours show ultraviolet light from NASA’s Solar Dynamics Observatory. Dr Iain Hannah, of the University of Glasgow, will present the image today at the National Astronomy Meeting in Llandudno.

    JAXA HINODE spacecraft
    JAXA Hinode spacecraft

    NASA SDO
    NASA/SDO

    NuSTAR usually spends its time examining the mysteries of black holes, supernovae and other high-energy objects in space. But it can also look closer to home to study our Sun.

    “We can see a few active regions on the Sun in this view,” said Hannah. “Our Sun is quietening down in its activity cycle, but still has a couple of years before it reaches a minimum.”

    Those active areas of the Sun are filled with flares, which are giant eruptions on the surface of the Sun that spew out charged particles and high-energy radiation. They occur when magnetic field lines become tangled and broken, and then reconnect. Due to its extreme sensitivity, NuSTAR’s telescope cannot view the larger flares. But it can help measure the energy of smaller microflares, which produce only one-millionth the energy of the larger flares.

    NuSTAR may also be able to directly detect hypothesised nanoflares, which would be only one-billionth the energy of flares. Nanoflares — which may help explain why the Sun’s atmosphere, or corona, is so much hotter than expected — would be hard to spot due to their small size. However, nanoflares may emit high-energy X-rays that NuSTAR has the sensitivity to detect. Astronomers suspect that these tiny flares, like their larger brethren, can send electrons flying at tremendous velocities. As the electrons zip around, they give off high-energy X-rays.

    “We still need the Sun to quieten down more over the next few years to have the ability to detect these events,” said Hannah, explaining that, while our Sun is approaching the tranquil end of its roughly 11-year activity cycle, it has been showing spurious bouts of high activity.

    Astronomers are also excited to use NuSTAR’s images of the Sun to pinpoint where energy from flares is released. While it is known that the energy is generally liberated in the upper solar atmosphere, the locations and detailed mechanisms are not precisely known.

    Cosmologists are looking forward to using NuSTAR’s solar observations, too. There is a slim chance the telescope could detect a hypothesised dark matter particle called the axion. Dark matter is a mysterious substance in our Universe that is about five times more abundant than the regular matter that makes up everyday objects and anything that gives off light. NuSTAR might be able to address this and other mysteries of the sun.

    “What’s great about NuSTAR is that the telescope is so versatile that we can hunt black holes millions of light-years away and we can also learn something fundamental about the star in our own backyard,” said Brian Grefenstette of the California Institute of Technology in Pasadena, an astronomer on the NuSTAR team.

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    The Royal Astronomical Society (RAS), founded in 1820, encourages and promotes the study of astronomy, solar-system science, geophysics and closely related branches of science.

     
  • richardmitnick 8:09 am on July 8, 2015 Permalink | Reply
    Tags: , , , , Royal Astronomical Society   

    From RAS: “Astronomers see pebbles poised to make planets” 

    Royal Astronomical Society

    Royal Astronomical Society

    08 July 2015
    Media contacts

    Dr Robert Massey
    Royal Astronomical Society
    Mob: +44 (0)794 124 8035
    rm@ras.org.uk

    Ms Anita Heward
    Royal Astronomical Society
    Mob: +44 (0)7756 034 243
    anitaheward@btinternet.com

    Dr Sam Lindsay
    Royal Astronomical Society
    Mob: +44 (0)7957 566 861
    sl@ras.org.uk

    Science contacts

    Dr Jane Greaves
    University of St Andrews
    Mob: +44 (0)7599 628 268
    Jsg5@st-and.ac.uk

    Dr Anita Richards
    University of Manchester
    Mob: +44 (0)7766 065 049
    a.m.s.richards@manchester.ac.uk

    1
    An artist’s impression of the belt of ‘pebbles’ in orbit around the star DG Tauri. The inset is a close up view of a section of the belt. Credit: J. Ilee. Adapted from original work by ESO/L. Calçada/M. Kornmesser, ALMA (ESO/NAOJ/NRAO)/L. Calçada (ESO).

    A team of astronomers led from St Andrews and Manchester universities today (6 July) announced the discovery of a ring of rocks circling a very young star. This is the first time these ‘pebbles’, thought to be a crucial link in building planets, have been detected. Dr Jane Greaves of the University of St Andrews presented the work at the National Astronomy Meeting at Venue Cymru in Llandudno, Wales.

    Planets are thought to form from the dust and gas that encircles young stars in a disk. Over time, dust particles stick together, until they build up bigger clumps. Eventually, these have enough mass that gravity becomes significant, and over millions of years the clumps crash together to make planets and moons. In our own Solar System, this process took place about 4500 million years ago, with the giant planet Jupiter the first to form.

    Since the 1990s, astronomers have found both disks of gas and dust, and nearly 2000 fully formed planets, but the intermediate stages of formation are harder to detect.

    Dr Greaves and team colleague Dr Anita Richards from the University of Manchester used the e-MERLIN array of radio telescopes centred on Jodrell Bank, Cheshire, and that stretches across England in a so-called interferometer, mimicking the resolution of a single large telescope. Richards took charge of the image processing, which was initially meant just to test the handling of the very large data stream that e-MERLIN generates.

    eMerlin Radio Telecope Array
    eMerlin Radio Telecope Array

    The scientists used the interferometer to observe the star DG Tauri, a relatively youthful star just 2.5 million years old and 450 light years away in the constellation of Taurus. Looking at radio wavelengths, they discovered a faint glow characteristic of rocks in orbit around the newly formed star.

    Richards said: “This was the first time for this project that we folded in data from the 76m-diameter Lovell Telescope at Jodrell Bank, which is the heart of the e-MERLIN array.

    Jodrell Bank Lovell Telescope
    Jodrell Bank Lovell Telescope

    We knew DG Tauri had a jet of hot gas flowing off its poles – a beacon for stars still in the process of forming – so we had an idea of what to look for.”

    ‘It was a real surprise to also see a belt of pebbles, with only a fraction of the data we hope to acquire. With the four-fold increase in radio bandwidth we are now working on, we hope to get similar images for a whole zoo of other young stars.”

    Dr Greaves added: “The extraordinarily fine detail we can see with the e-MERLIN telescopes was the key to this discovery. We could zoom into a region as small as the orbit of Jupiter would be in the Solar System. We found a belt of pebbles strung along a very similar orbit – just where they are needed if a planet is to grow in the next few million years. Although we thought this was how planets must get started, it’s very exciting to actually see the process in action!”

    2
    An e-MERLIN map of the star DG Tauri. The yellow and red areas show what is thought to be a ring of pebble-sized clumps in orbit around the star. Credit: J. Greaves / A. Richards / JCBA.

    The e-MERLIN observations were made at a wavelength of 4.6 cm (about a third of that used in microwave ovens). To give off these radio waves, rocky chunks at least a centimetre in size are needed, and the shape of the belt confirms the rocks as the source of the radio waves.

    Team member Dr John Ilee, also of St Andrews, is working on a related European project to investigate protoplanetary discs around young stars. He added: “Long wavelength data, such these fantastic e-MERLIN results, will be essential in constraining the next generation of computer models of discs around young stars. Having an accurate idea of the location and amount of the centimetre-sized material in the disc will bring us closer to a consistent picture of how planets may eventually form.”

    Greaves leads an international team known as PEBBLeS – the Planet Earth Building Blocks Legacy e-MERLIN Survey. By imaging the rocky belts of many stars, the team will look for clues to how often planets form, and where, around stars that will evolve into future suns like our own. The ultimate aim is to zoom in and see ‘extrasolar Earths’ being born, five times closer in to their host stars than Jupiter’s orbit. Upgrades to e-MERLIN’s capabilities in the next few years, as well as the construction of the new Square Kilometre Array (with its HQ at Jodrell Bank), make this a real possibility.

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    The Royal Astronomical Society (RAS), founded in 1820, encourages and promotes the study of astronomy, solar-system science, geophysics and closely related branches of science.

     
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