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  • 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.

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    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.

     
  • richardmitnick 6:27 am on July 7, 2015 Permalink | Reply
    Tags: , , Carrington-L5 mission, Royal Astronomical Society,   

    From RAS: “Carrington-L5: A UK mission to provide 5-day space weather forecasts” 

    Royal Astronomical Society

    Royal Astronomical Society

    05 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 contact
    Dr. Markos Trichas
    Principal Mission Systems Engineer
    Airbus Defence and Space (UK)
    markos.trichas@astrium.eads.net
    http://www.airbusdefenceandspace.com

    1
    Images of the Carrington-L5 mission concept. Credit: Airbus Defence and Space (UK)

    Coronal mass ejections (CME), billion-tonne solar plasma eruptions moving towards the Earth at up to 2500 kilometres per second, can cause extensive and expensive disruption by damaging power, satellite and communication networks. A UK consortium is proposing an operational mission, called Carrington-L5, to give a five-day warning of hazardous solar activity that could inflict severe damage to our infrastructure. The mission concept will be presented at the National Astronomy Meeting in Llandudno by Dr Markos Trichas of Airbus Defence and Space (UK).

    In response to the UK government adding solar storms to the National Risk Register of Civil Emergencies in 2011, the Met Office Space Weather Operations Centre (MOSWOC) was created to protect the country from the serious threats posed by space weather events. Current warnings of CME arrival at Earth use facilities like SOHO, STEREO and SDO.

    NASA SOHO
    NASA/SOHO

    NASA STEREO spacecraft
    NASA/STEREO

    NASA SDO
    NASA/SDO

    However, none of these are designed to provide 24/7 data, necessary for accurate and timely forecasts and all the spacecraft are ageing rapidly, with some of them having spent more than two decades in space. More importantly, STEREO, which provided essential data for early warnings, is now behind the Sun and is unable to communicate any data back to Earth. With the current spacecraft configuration, the accuracy of CME arrival time forecasts has been significantly degraded.

    The goal of the consortium is to replace data provided by the STEREO satellites, through a new mission capable of providing continuous data from a stable orbit, necessary for the Met Office to provide 5-day forecasts and increase the accuracy of CME arrival forecasts. The proposed Carrington-L5 mission is named after the British scientist who monitored the strongest geomagnetic storm on record, the event of 1859. To provide the necessary warning time, Carrington-L5 will utilize a gravitational balance point, known as L5, which would allow it to trail the Earth in its orbit around the Sun by about 150 million kilometres. From this perspective, the spacecraft would have a view of what’s happening on the surface of the Sun several days in advance of when an active area spins round towards Earth.

    The Carrington-L5 mission concept study is led by Airbus Defence and Space (UK), in collaboration with the Met Office, Mullard Space Science Laboratory, Rutherford Appleton Laboratory and Imperial College London. The proposed mission will reuse systems developed by Airbus for previous space missions, in order to minimise the cost. It will carry all instruments identified by MOSWOC as critical, and will be able to operate for at least a decade even under extreme space weather conditions.

    “Within the UK, we have the heritage and experience to create this mission on a relatively short timescale and at a low overall cost,” said Trichas. “All components we are planning to use for the Carrington-L5 spacecraft and payload have flown before or are in an advanced stage of development. This will minimise the cost of procurement and massively increase the benefits to our economy while allowing the growth of the UK space industry.”

    See the full article for a full list of available Carrington images.

    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 4:20 am on May 7, 2015 Permalink | Reply
    Tags: , , Royal Astronomical Society   

    From RAS: “Fresh evidence for how water reached earth found in asteroid debris” 

    Royal Astronomical Society

    Royal Astronomical Society

    05 May 2015
    Media contact
    Lee Page
    University of Warwick
    Tel: +44 (0)247 657 4255
    Mob: +44 (0)7920 531 221
    l.page@warwick.ac.uk
    Science contacts
    Dr Roberto Raddi
    University of Warwick
    Tel: +44 (0)24 765 73869
    R.Raddi@warwick.ac.uk

    Prof Boris Gänsicke
    University of Warwick
    Tel: +44 (0)247 657 4741
    Boris.Gaensicke@warwick.ac.uk

    1
    Artist’s impression of a rocky and water-rich asteroid being torn apart by the strong gravity of the white dwarf star. Similar objects in the Solar System likely delivered the bulk of water on Earth and represent the building blocks of the terrestrial planets. Image copyright Mark A. Garlick, http://space-art.co.uk, University of Warwick

    Water delivery via asteroids or comets is likely taking place in many other planetary systems, just as it happened on Earth, according to new research. In work led by Dr Roberto Raddi of the University of Warwick, a team of astronomers find evidence that numerous planetary bodies, including asteroids and comets, contain large amounts of water. The research appears in the journal Monthly Notices of the Royal Astronomical Society.

    The findings add further support to the possibility that water can be delivered to Earth-like planets via such bodies to create a suitable environment for the formation of life.

    Commenting on the results, Dr Raddi said: “Our research has found that, rather than being unique, water-rich asteroids similar to those found in our Solar System appear to be commonplace. Accordingly, many planets may contain, or have contained, a volume of water comparable to that found in the Earth.

    ‘It is believed that the Earth was initially dry, but our research strongly supports the view that the oceans we have today were created as a result of impacts by water-rich comets or asteroids”.

    In observations obtained at the William Herschel Telescope [WHT] in the Canary Islands, the Warwick astronomers detected a large quantity of hydrogen and oxygen in the atmosphere of a white dwarf (known as SDSS J1242+5226), the compact remnant of a Sun-like star at the end of its life.

    ING William Herschel Telescope
    ING William Herschel Telescope Interior
    WHT

    This is direct evidence that a water-rich exo-asteroid was disrupted and eventually delivered the water it contained onto the star. This world, the researchers discovered, was comparable in size to Ceres – at 900km across, the largest asteroid in the Solar System.

    “The amount of water found in SDSS J1242+5226 is equivalent to 30-35% of the oceans on Earth”, explained Dr Raddi.

    The impact of water-rich asteroids or comets onto a planet or white dwarf results in the mixing of hydrogen and oxygen into their atmospheres. Both elements were detected in large amounts in SDSS J1242+5226.

    Research co-author Professor Boris Gänsicke, also of the University of Warwick, explained: “Oxygen, which is a relatively heavy element, will sink deep down into the white dwarf over time, and hence a while after the disruption event is over, it will no longer be visible.

    “In contrast, hydrogen is the lightest element; it will always remain floating near the surface of the white dwarf where it can easily be detected. There are many white dwarfs that hold large amounts of hydrogen in their atmospheres, and this new study suggests that this is evidence that water-rich asteroids or comets are common around other stars.”

    The new work appears in Raddi, R.; Gaensicke, B. T.; Koester, D.; Farihi, J.; Hermes, J. J.; Scaringi, S.; Breedt, E.; Girven, J., Likely detection of water-rich asteroid debris in a metal-polluted white dwarf, Monthly Notices of the Royal Astronomical Society, Oxford University Press, in press.

    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 9:35 am on April 22, 2015 Permalink | Reply
    Tags: , , Royal Astronomical Society   

    From RAS: “As bright as a hundred million Suns: the clusters of monster stars that lit up the early universe” 

    Royal Astronomical Society

    Royal Astronomical Society

    22 April 2015
    Science contact
    Dr Shantanu Basu
    University of Western Ontario
    Canada
    Tel: +1 519 661 2111 x86706
    Mob: +1 519 520 7856
    basu@uwo.ca

    Media contact
    Dr Robert Massey
    Royal Astronomical Society
    Tel: +44 (0)20 7734 3307 x214
    Mob: +44 (0)794 124 8035
    rm@ras.org.uk

    The first stars in the Universe were born several hundred million years after the Big Bang, ending a period known as the cosmological ‘dark ages’ – when atoms of hydrogen and helium had formed, but nothing shone in visible light. Now two Canadian researchers have calculated what these objects were like: they find that the first stars could have clustered together in phenomenally bright groups, with periods when they were as luminous as 100 million Suns. Alexander DeSouza and Shantanu Basu, both of the University of Western Ontario in Canada, publish their results in a paper in Monthly Notices of the Royal Astronomical Society.

    1
    An artist’s impression of some of the first stars in the early Universe. Five protostars are seen here forming in the centre of disks of gas. Credit: Shantanu Basu, University of Western Ontario.

    The two scientists modelled how the luminosity of the stars would have changed as they formed from the gravitational collapse of disks of gas. The early evolution turns out to be chaotic, with clumps of material forming and spiralling into the centre of the disks, creating bursts of luminosity a hundred times brighter than average. These first stars would have been at their brightest when they were ‘protostars‘, still forming and pulling in material.

    In a small cluster of even 10 to 20 protostars, the ongoing bursts would mean the cluster would spend large periods with enhanced brightness. According to the simulation, every so often a cluster of 16 protostars could see its luminosity increase by a factor of up to 1000, to an extraordinary 100 million times the brightness of the Sun.

    The earliest stars lived very short lives and produced the first heavy elements, like the carbon and oxygen that the chemistry of life depends upon.

    Light from these stars has travelled towards us for almost 13 billion years, so to observers on Earth they look very faint and also have their light stretched out into infrared wavelengths by the expansion of the universe. This makes these stars very hard to observe, but the next generation James Webb Space Telescope (JWST) will survey the skies to look for them.

    NASA Webb Telescope
    JWST

    Although the luminosity of an individual first star is probably too faint for JWST to spot it, the new work suggests that clusters of the first protostars could be prominent beacons in the early universe.

    Dr Basu commented: “Seeing the very first stars is a key science goal for JWST and part of astronomers’ quest to track the history of the cosmos. If we’re right, then in just a few years’ time, we could see these enigmatic and dazzlingly bright objects as they came into being, and lit up the universe around them.”

    Further information

    The new work appears in A. L. DeSouza & S. Basu, The Luminosity of Population III Star Clusters, Monthly Notices of the Royal Astronomical Society, vol. 450, pp. 295-304, 2015, published by Oxford University Press.

    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 8:39 pm on March 22, 2015 Permalink | Reply
    Tags: , , Mass extinctions, Royal Astronomical Society   

    From RAS: “Does dark matter cause mass extinctions and geologic upheavals?” 

    Royal Astronomical Society

    Royal Astronomical Society

    19 February 2015

    Media contacts

    James Devitt
    Deputy Director for Media Relations
    New York University
    United States
    Tel: +1 (212) 998 6808
    Mob: +1 (914) 522 3774
    james.devitt@nyu.edu

    Robert Massey
    Royal Astronomical Society
    Tel: +44 (0)20 7734 3307 x214
    Mob: +44 (0)794 124 8035
    rm@ras.org.uk

    Science contact

    Prof Michael Rampino
    New York University
    United States
    Tel: +1 (718) 578 1442
    mrr1@nyu.edu

    1
    NGC 4565, an edge-on spiral galaxy. The stars, dust and gas are concentrated into a thin disc, much like the one in our Milky Way galaxy. NGC 4565 and apparently smaller NGC 4562. 24-inch telescope on Mt. Lemmon, AZ. Courtesy of Joseph D. Schulman

    Mt Lemon 24 inch telescope
    Mt Lemon 24 inch telescope

    Research by New York University Biology Professor Michael Rampino concludes that Earth’s infrequent but predictable path around and through our Galaxy’s disc may have a direct and significant effect on geological and biological phenomena occurring on Earth. In a new paper in Monthly Notices of the Royal Astronomical Society, he concludes that movement through dark matter may perturb the orbits of comets and lead to additional heating in the Earth’s core, both of which could be connected with mass extinction events.

    The galactic disc is the region of the Milky Way galaxy where our solar system resides. It is crowded with stars and clouds of gas and dust, and also a concentration of elusive dark matter – small subatomic particles that can be detected only by their gravitational effects.

    Previous studies have shown that Earth rotates around the disc-shaped Galaxy once every 250 million years. But the Earth’s path around the Galaxy is wavy, with the Sun and planets weaving through the crowded disc approximately every 30 million years. Analysing the pattern of the Earth’s passes through the Galactic disc, Rampino notes that these disc passages seem to correlate with times of comet impacts and mass extinctions of life. The famous comet strike 66 million ago that led to the extinction of the dinosaurs is just one example.

    What causes this correlation between Earth’s passes through the Galactic disc, and the impacts and extinctions that seem to follow?

    While travelling through the disc, the dark matter concentrated there disturbs the pathways of comets typically orbiting far from the Earth in the outer Solar System, Rampino points out. This means that comets that would normally travel at great distances from the Earth instead take unusual paths, causing some of them to collide with the planet.

    But even more remarkably, with each dip through the disc, the dark matter can apparently accumulate within the Earth’s core. Eventually, the dark matter particles annihilate each other, producing considerable heat. The heat created by the annihilation of dark matter in Earth’s core could trigger events such as volcanic eruptions, mountain building, magnetic field reversals, and changes in sea level, which also show peaks every 30 million years. Rampino therefore suggests that astrophysical phenomena derived from the Earth’s winding path through the Galactic disc, and the consequent accumulation of dark matter in the planet’s interior, can result in dramatic changes in Earth’s geological and biological activity.

    His model of dark matter interactions with the Earth as it cycles through the Galaxy could have a broad impact on our understanding of the geological and biological development of Earth, as well as other planets within the Galaxy.

    Rampino said: “We are fortunate enough to live on a planet that is ideal for the development of complex life. But the history of the Earth is punctuated by large scale extinction events, some of which we struggle to explain. It may be that dark matter – the nature of which is still unclear but which makes up around a quarter of the universe – holds the answer. As well as being important on the largest scales, dark matter may have a direct influence on life on Earth.”

    In the future, he suggests, geologists might incorporate these astrophysical findings in order to better understand events that are now thought to result purely from causes inherent to the Earth. This model, Rampino adds, likewise provides new knowledge of the possible distribution and behaviour of dark matter within the Galaxy.

    See the full article here.

    Please help promote STEM in your local schools.

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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 5:32 am on December 22, 2014 Permalink | Reply
    Tags: , , , , Royal Astronomical Society   

    From RAS: “The Milky Way’s new neighbour” 

    Royal Astronomical Society

    Royal Astronomical Society

    19 December 2014
    Media contact
    Robert Massey
    Royal Astronomical Society
    Mob: +44 (0)794 124 8035
    rm@ras.org.uk

    Science contact
    Prof Dimitry Makarov
    Special Astrophysical Observatory
    Nizhniy Arkhyz
    Karachai-Cherkessia
    Russia
    Tel: +7 87822 93404
    dim@sao.ru

    The Milky Way, the galaxy we live in, is part of a cluster of more than 50 galaxies that make up the ‘Local Group’, a collection that includes the famous Andromeda galaxy and many other far smaller objects. Now a Russian-American team have added to the canon, finding a tiny and isolated dwarf galaxy almost 7 million light years away. Their results appear in Monthly Notices of the Royal Astronomical Society.

    l
    Local Group

    a
    The Andromeda Galaxy is a spiral galaxy approximately 2.5 million light-years away in the constellation Andromeda. The image also shows Messier Objects 32 and 110, as well as NGC 206 (a bright star cloud in the Andromeda Galaxy) and the star Nu Andromedae. This image was taken using a hydrogen-alpha filter.
    Adam Evans

    The team, led by Prof Igor Karachentsev of the Special Astrophysical Observatory in Karachai-Cherkessia, Russia, found the new galaxy, named KKs3, using the Hubble Space Telescope Advanced Camera for Surveys (ACS) in August 2014. Kks3 is located in the southern sky in the direction of the constellation of Hydrus and its stars have only one ten-thousandth of the mass of the Milky Way.

    NASA Hubble Telescope
    NASA Hubble schematic
    Hubble

    NASA Hubble ACS
    HUbble ACS

    h
    The core of the galaxy is the right hand dark object at the top centre of the image, with its stars spreading out over a large section around it. (The left hand of the two dark objects is a much nearer globular star cluster.) Credit: D. Makarov. Kks3 is a ‘dwarf spheroidal or dSph galaxy’ , lacking features like the spiral arms found in our own galaxy. These systems also have an absence of the raw materials (gas and dust) needed for new generations of stars to form, leaving behind older and fainter relics. In almost every case, this raw material seems to have been stripped out by nearby massive galaxies like Andromeda, so the vast majority of dSph objects are found near much bigger companions.

    Isolated objects must have formed in a different way, with one possibility being that they had an early burst of star formation that used up the available gas resources. Astronomers are particularly interested in finding dSph objects to understand galaxy formation in the universe in general, as even HST struggles to see them beyond the Local Group. The absence of clouds of hydrogen gas in nebulae also makes them harder to pick out in surveys, so scientists instead try to find them by picking out individual stars.

    For that reason, only one other isolated dwarf spheroidal, KKR 25, has been found in the Local Group, a discovery made by the same group back in 1999.

    Team member Prof Dimitry Makarov, also of the Special Astrophysical Observatory, commented: “Finding objects like Kks3 is painstaking work, even with observatories like the Hubble Space Telescope. But with persistence, we’re slowly building up a map of our local neighbourhood, which turns out to be less empty than we thought. It may be that are a huge number of dwarf spheroidal galaxies out there, something that would have profound consequences for our ideas about the evolution of the cosmos.”

    The team will continue to look for more dSph galaxies, a task that will become a little easier in the next few years, once instruments like the James Webb Space Telescope and the European Extremely Large Telescope begin service.

    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 6:09 am on December 20, 2014 Permalink | Reply
    Tags: , , , , Royal Astronomical Society   

    From RAS: “Science and Innovation Strategy: RAS Response” 

    Royal Astronomical Society

    Royal Astronomical Society

    Friday, 19 December 2014
    No Writer Credit

    The UK government published its new Science and Innovation strategy on Wednesday 17 December. The new document, “Our Plan for Growth: science and innovation” includes a number of positive announcements and restatements of support for projects in astronomy and geophysics, such as the capital funding for the Square Kilometre Array (SKA) radio observatory and the Polar Research Ship, and the more recent support for the European Space Agency to develop the ExoMars mission.

    SKA Pathfinder Radio Telescope
    SKA Pathfinder telescope

    ESA ExoMars
    ESA/ExoMars

    The Society welcomes these, along with the statement of support for peer review in investment decisions; the importance of international collaboration, the new targets for the recruitment of maths and physics teachers, the new postgraduate loans scheme, the recognition of the success of the Gaia and Rosetta missions and the opportunities presented by Major Tim Peake’s flight to the International Space Station next year.

    ESA Gaia satellite
    ESA/Gaia

    ESA Rosetta spacecraft
    ESA/Rosetta

    More generally, one of the long-standing concerns of the scientific community has been the low level of public (and private) funding for science compared with other EU and OECD countries. The new strategy explicitly addresses this, with a pledge to examine resource spending in the 2015 Spending Review. The Society welcomes this commitment and the overarching statement that policies for science and innovation should not detract from the importance of fundamental research being carried out for its own sake.

    International collaboration, including UK leadership in European scientific programmes such as Horizon 2020, also has a high prominence. The Society endorses this view and the pledge to use the UK presidency of the EU to support this activity.

    The RAS however remains concerned about several fundamental areas, including the lack of commitment to protect the science ‘ring fence’. This flat cash budget has already been eroded significantly since 2010 and even a low inflation environment will have a serious impact on purchasing power in the years ahead. If this policy continues, the inevitable outcome will be a reduction in the resources (not least postgraduate students and postdoctoral researchers) needed to exploit scientific data. This could greatly hinder the UK’s ability to reap the full benefits of the capital investment in scientific projects. And although there is recognition of the need to recruit the most talented people from across the globe, though there seems no prospect of a loosening of the restrictions on immigration that can make such recruitment almost impossible in practice.

    President of the Royal Astronomical Society Prof Martin Barstow commented: “I am delighted to see that the Government so clearly recognises the importance of scientific research, including the ‘blue skies’ sciences that are so important to the RAS and our Fellows and which are so valued by the wider public. There has though been a hollowing out of the resource budget needed to make the most of our involvement and investment in major scientific programmes, something that will need to be tackled if the UK is to remain a world player in research. As RAS President I will be pressing the Government to tackle this in next year’s Spending Review, in order to deliver the secure environment that will allow our researchers to flourish.”

    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 6:08 am on December 15, 2014 Permalink | Reply
    Tags: , , , , Royal Astronomical Society   

    From RAS: “Stretched-out solid exoplanets “ 

    Royal Astronomical Society

    Royal Astronomical Society

    Monday, 15 December 2014
    Media contact

    Dr Robert Massey
    Royal Astronomical Society
    Tel: +44 (0)20 7734 3307 x214
    Mob: +44 (0)794 124 8035
    rm@ras.org.uk

    Science contact

    Prabal Saxena
    School of Physics, Astronomy and Computational Sciences
    George Mason University
    Virginia
    United States
    Tel: +1 516 978 2158
    psaxena2@masonlive.gmu.edu

    Astronomers could soon be able to find rocky planets stretched out by the gravity of the stars they orbit, according to a group of researchers in the United States. The team, led by Prabal Saxena of George Mason University, describe how to detect these exotic worlds in a paper in the journal Monthly Notices of the Royal Astronomical Society.

    p
    An artist’s impression of a stretched rocky planet in orbit around a red dwarf star. So close to the star, there is a difference in the strength of the gravitational field on each side of the planet, stretching it significantly. Credit: Shivam Sikroria.

    Since the first discovery in 1993, more than 1800 planets have been found in orbit around stars other than our Sun. These ‘exoplanets’ are incredibly diverse, with some gaseous like Jupiter and some mostly rocky like the Earth. The worlds also orbit their stars at very different distances, from less than a million km to nearly 100 billion km away. Planets that are very close to their stars experience harsh conditions, often with very high temperatures (>1000 degrees Celsius) and significant stretching from the tidal forces resulting from the stellar gravitational field. This is most obvious with planets with a large atmosphere (so-called ‘hot Jupiters’) but harder to see with the rockier objects.

    Prabal and his team modelled cases where the planets are in orbit close to small red dwarf stars, much fainter than our Sun, but by far the most common type of star in the Galaxy. The planets’ rotation is locked, so the worlds keep the same face towards the stars they orbit, much like the Moon does as it moves around the Earth. According to the scientists, in these circumstances the distortion of the planets should be detectable in transit events, where the planets moves in front of their stars and blocks out some of their light.

    If astronomers are able to find these extreme exoplanets, it could give them new insights into the properties of Earth-like planets as a whole. Prabal comments, “Imagine taking a planet like the Earth or Mars, placing it near a cool red star and stretching it out. Analysing the new shape alone will tell us a lot about the otherwise impossible to see internal structure of the planet and how it changes over time.”

    The subtle signals from stretched rocky planets could be found by some current telescopes, and certainly by much more powerful observatories like the James Webb Space Telescope (JWST) and the European Extremely Large Telescope (E-ELT) that are due to enter service in the next few years.

    NASA Webb Telescope
    NASA/Webb

    ESO E-ELT
    ESO E-ELT Interior
    ESO/E-ELT

    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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