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  • richardmitnick 9:22 pm on May 22, 2015 Permalink | Reply
    Tags: Astronomy, , ,   

    From New Scientist: “Supernova space bullets could have seeded Earth’s iron core” 

    NewScientist

    New Scientist

    20 May 2015
    Jacob Aron

    1
    Shooting stars (Image: X-ray: NASA/CXC/SAO; Infrared: NASA/JPL-Caltech; Optical: MPIA, Calar Alto, O. Krause et al)

    Supernova shoot-em-ups could be responsible for Earth’s iron core. An analysis suggests that certain stars fire off massive iron bullets when they die.

    Stars fuse the hydrogen and helium present in the early universe into heavier elements, like iron. When stars reach the end of their lives, they explode in supernovae, littering these elements throughout space where they can eventually form planets.

    A particular kind of supernova called a type Ia, the result of the explosion of a dense stellar corpse called a white dwarf star, seems to be responsible for most of the iron on Earth.

    These stars also play an important role in our understanding of distance in the universe. That’s because the white dwarfs only blow up when they reach a certain, fixed mass, so we can use the light of these explosions as a “standard candle” to tell how far away they are.

    But astronomers still haven’t figured out exactly what causes white dwarfs to hit this critical limit.

    “Most of our iron on Earth comes from supernovae of this kind,” says Noam Soker of the Technion Israel Institute of Technology in Haifa. “It is embarrassing that we still don’t know what brings these white dwarfs to explode.”

    Lumpy stars

    When a star goes supernova, it leaves behind a cloud of ejected material called a supernova remnant. This remnant should be spherical – but some have extra bumps that could offer a clue to the supernova’s origin.

    Now Soker and his colleague Danny Tsebrenko say that massive clumps of iron produced within a white dwarf in the process of going supernova could be punching through the remnant like bullets, creating these bumps. The iron bullets aren’t solid chunks of metal, but a more diffuse cloud of molecules.

    Some supernova remnants have two bumps on opposite sides, which the researchers call “ears”.

    The iron bullets form along the rotation axis of an exploding white dwarf, firing out at either end, says Soker. A white dwarf can only be spinning fast enough to allow this if it is the result of two smaller dwarfs merging, he adds.

    The bullets could also shed light on our origins. Soker and Tsebrenko estimate that these clouds of iron would be several times the mass of Jupiter. They would spread and could eventually seed dust clouds with iron that would go on to form stars and planets, providing an origin for Earth’s core, says Soker.

    Reference: arxiv.org/abs/1505.02034v1

    See the full article here.

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  • richardmitnick 1:21 pm on May 22, 2015 Permalink | Reply
    Tags: Astronomy, ,   

    From Hubble: “Hubble’s Look at an Extragalactic Peculiarity” 

    NASA Hubble Telescope

    Hubble

    May 22, 2015
    Karl Hille

    1
    NASA/ESA Hubble

    This galaxy goes by the name of ESO 162-17 and is located about 40 million light-years away in the constellation of Carina. At first glance this image seems like a fairly standard picture of a galaxy with dark patches of dust and bright patches of young, blue stars. However, a closer look reveals several peculiar features.

    Firstly, ESO 162-17 is what is known as a peculiar galaxy — a galaxy that has gone through interactions with its cosmic neighbors, resulting in an unusual amount of dust and gas, an irregular shape, or a strange composition.

    Secondly, on February 23, 2010 astronomers observed the supernova known as SN 2010ae nestled within this galaxy. The supernova belongs to a recently discovered class of supernovae called Type Iax supernovae. This class of objects is related to the better known Type-Ia supernovae.

    Type Ia supernovae result when a white dwarf accumulates enough mass either from a companion or, rarely, through collision with another white dwarf, to initiate a catastrophic collapse followed by a spectacular explosion as a supernova. Type Iax supernovae also involve a white dwarf as the central star, but in this case it may survive the event. Type Iax supernovae are much fainter and rarer than Type Ia supernovae, and their exact mechanism is still a matter of open debate.

    The rather beautiful four-pointed shape of foreground stars distributed around ESO 162-17 also draws the eye. This is an optical effect introduced as the incoming light is diffracted by the four struts that support the Hubble Space Telescope’s small secondary mirror.

    See the full article here.

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

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  • richardmitnick 1:05 pm on May 22, 2015 Permalink | Reply
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    From Hubble: “Hubble Revisits Tangled NGC 6240″ 

    NASA Hubble Telescope

    Hubble

    May 22, 2015
    Ashley Morrow

    1
    Image credit: NASA, ESA, the Hubble Heritage (STScI/AURA)-ESA/Hubble Collaboration, and A. Evans (University of Virginia, Charlottesville/NRAO/Stony Brook University)

    Not all galaxies are neatly shaped, as this new NASA/ESA Hubble Space Telescope image of NGC 6240 clearly demonstrates. Hubble previously released an image of this galaxy back in 2008, but the knotted region, shown here in a pinky-red hue at the center of the galaxies, was only revealed in these new observations from Hubble’s Wide Field Camera 3 and Advanced Camera for Surveys.

    NASA Hubble WFC3
    WFC3

    NASA Hubble ACS
    ACS

    NGC 6240 lies 400 million light-years away in the constellation of Ophiuchus (The Serpent Holder). This galaxy has an elongated shape with branching wisps, loops and tails. This mess of gas, dust and stars bears more than a passing resemblance to a butterfly and a lobster.

    This bizarrely-shaped galaxy did not begin its life looking like this; its distorted appearance is a result of a galactic merger that occurred when two galaxies drifted too close to one another. This merger sparked bursts of new star formation and triggered many hot young stars to explode as supernovae. A new supernova, not visible in this image was discovered in this galaxy in 2013, named SN 2013dc.

    At the center of NGC 6240 an even more interesting phenomenon is taking place. When the two galaxies came together, their central black holes did so, too. There are two supermassive black holes within this jumble, spiraling closer and closer to one another. They are currently only some 3,000 light-years apart, incredibly close given that the galaxy itself spans 300,000 light-years. This proximity secures their fate as they are now too close to escape each other and will soon form a single immense black hole.

    See the full article here.

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

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  • richardmitnick 9:12 am on May 22, 2015 Permalink | Reply
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    From CAASTRO: “Old, gas-rich galaxies likely had early star formation boom” 

    CAASTRO bloc

    CAASTRO ARC Centre of Excellence for All Sky Astrophysics

    22 May 2015
    No Writer Credit

    The most massive stars (with masses up to a hundred times the mass of our sun) explode as supernovae at the end of their life and release huge amounts of energy and material into their neighbourhoods. These phenomena are so energetic that they can alter the rate of star formation and impact the chemical composition of galaxies since heavy elements are synthesised in the interior of stars via nuclear fusion reactions. Astronomical observations suggest that many supernova explosions adding up can halt the formation of new stars and expel enriched gas out of galaxies. Indirect observations seem also to suggest that a supermassive black hole resides at the centre of virtually all galaxies. We still do not know how these objects formed but we believe that their masses are greater than 1 million solar masses and the energy emitted by gas falling into them could produce outflows at even higher velocity than the supernova driven outflows (thousands of km/s).

    1

    In a recent University of Melbourne led paper, Dr Edoardo Tescari and colleagues present the first results of the CAASTRO supported AustraliaN GADGET-3 early Universe Simulations project, or ANGUS for short. The team ran numerical simulations of the Universe in its early stages (up to 13 billion years ago) to study formation and evolution of galaxies and how they interact with their environment. They focused in particular on the so called “feedback” effects associated with the formation of stars and supermassive black holes at the centre of galaxies.

    Including the effects of both, supernovae and supermassive black holes, their simulations tested different configurations of feedback (early/late and weak/strong). The researchers found that efficient feedback at early times is needed to reproduce new observations of the global amount of star formation in the “young” Universe. They propose the following theoretical scenario to explain their results: galaxies that formed 13 billion years ago contained a lot of gas that was quickly converted into many stars. The back-reaction of the star formation processes (i.e. feedback) has since suppressed subsequent star formation especially in low mass galaxies.

    Publication details:
    E. Tescari, A. Katsianis, S. Wyithe, K. Dolag, L. Tornatore, P. Barai, M. Viel, S. Borgani in MNRAS (2014) Simulated star formation rate functions at z ~ 4 – 7, and the role of feedback in high-z galaxies

    See the full article here.

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    Astronomy is entering a golden age, in which we seek to understand the complete evolution of the Universe and its constituents. But the key unsolved questions in astronomy demand entirely new approaches that require enormous data sets covering the entire sky.

    In the last few years, Australia has invested more than $400 million both in innovative wide-field telescopes and in the powerful computers needed to process the resulting torrents of data. Using these new tools, Australia now has the chance to establish itself at the vanguard of the upcoming information revolution centred on all-sky astrophysics.

    CAASTRO has assembled the world-class team who will now lead the flagship scientific experiments on these new wide-field facilities. We will deliver transformational new science by bringing together unique expertise in radio astronomy, optical astronomy, theoretical astrophysics and computation and by coupling all these capabilities to the powerful technology in which Australia has recently invested.

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  • richardmitnick 8:51 am on May 22, 2015 Permalink | Reply
    Tags: , Astronomy, ,   

    From ANU: “Supernova ignition surprises scientists” 

    ANU Australian National University Bloc

    Australian National University

    21 May 2015
    No Writer Credit

    1
    NEWS from the Australian Gemini Office! ANU astronomer Dr Brad Tucker and his team used the Kepler Space Telescope together with the Gemini 8m telescope to catch supernovae in the act.

    Gemini South telescope
    Gemini South Interior
    Gemini

    Photo: Supernova SN2012fr, just to the left of the centre of the galaxy, outshone the rest of the galaxy for several weeks: Credit Brad Tucker and Emma Kirby

    Scientists have captured the early death throes of supernovae for the first time and found that the universe’s benchmark explosions are much more varied than expected.

    The scientists used the Kepler space telescope to photograph three type 1a supernovae in the earliest stages of ignition.

    NASA Kepler Telescope
    NASA/Kepler

    They then tracked the explosions in detail to full brightness around three weeks later, and the subsequent decline over the next few months.

    They found the initial stages of a supernova explosion did not fit with the existing theories.

    “The stars all blow up uniquely. It doesn’t make sense,” said Dr Brad Tucker, from the Research School of Astronomy and Astrophysics.

    “It’s particularly weird for these supernovae because even though their initial shockwaves are very different, they end up doing the same thing.”

    Before this study, the earliest type 1a supernovae had been glimpsed was more than 2.5 hours after ignition, after which the explosions all followed an identical pattern.

    This led astronomers to theorise that supernovae, the brilliant explosions of dying stars, all occurred through an identical process.

    Astronomers had thought supernovae all happened when a dense star steadily sucked in material from a large nearby neighbour until it became so dense that carbon in the star’s core ignited.

    “Somewhat to our surprise the results suggest an alternative hypothesis, that a violent collision between two smallish white dwarf stars sets off the explosion,” said lead researcher Dr Robert Olling, from the University of Maryland in the United States.

    At the peak of their brightness, supernovae are brighter than the billions of stars in their galaxy. Because of their brightness, astronomers have been able to use them to calculate distances to distant galaxies.

    Measurements of distant supernovae led to the discovery that some unknown force, now called dark energy, is causing the accelerated expansion of the universe. Brian Schmidt from the ANU, Saul Perlmutter (Berkeley) and Adam Reiss (Johns Hopkins) were awarded the Nobel prize in 2011 for this discovery.

    Dr Tucker said the new results did not undermine the discovery of dark energy.

    “The accelerating universe will not now go away – they will not have to give back their Nobel prizes,” he said.

    “The new results will actually help us to better understand the physics of supernovae, and figure out what is this dark energy that is dominating the universe.”

    The findings are published in Nature.

    See the full article here.

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    ANU Campus

    ANU is a world-leading university in Australia’s capital city, Canberra. Our location points to our unique history, ties to the Australian Government and special standing as a resource for the Australian people.

    Our focus on research as an asset, and an approach to education, ensures our graduates are in demand the world-over for their abilities to understand, and apply vision and creativity to addressing complex contemporary challenges.

     
  • richardmitnick 6:59 pm on May 21, 2015 Permalink | Reply
    Tags: Astronomy, ,   

    From ICRAR: “Galaxy’s snacking habits revealed” 

    International Center for Radio Astronomy Research

    International Centre for Radio Astronomy Research

    21 May, 2015

    Science Team contacts:

    Dr Ángel R. López-Sánchez
    Australian Astronomical Observatory / Macquarie University
    Ph: +61 2 9372 4898
    M: +61 406 265 917
    E: angel.lopez-sanchez@aao.gov.au

    Dr Tobias Westmeier
    The International Centre for Radio Astronomy Research / University of Western Australia
    Ph: +61 8 6488 4592
    M: (call Pete Wheeler)
    E: tobias.westmeier@icrar.org

    Dr Baerbel Koribalski
    Commonwealth Scientific and Industrial Research Organisation (CSIRO)
    Ph: +61 2 9372 4361
    M: +61 450 624 954
    E: baerbel.koribalski@csiro.au
    Press Officer contacts

    Dr Amanda Bauer
    Australian Astronomical Observatory (AAO)
    Ph: +61 2 9372 4852
    M: +61 447 029 368
    E: amanda.bauer@aao.gov.au

    Pete Wheeler
    The International Centre for Radio Astronomy Research (ICRAR)
    Ph: +61 8 6488 7758
    M: +61 0423 982 018
    E: pete.wheeler@icrar.org

    1
    Multiwavelength image of galaxies NGC 1512 and NGC 1510 combining optical and near-infrared data (light blue, yellow, orange), ultraviolet data (dark blue), mid-infrared data (red), and radio data (green).

    2
    A chemical enrichment map of the NGC 1512 and NGC 1510 galaxy system showing the amount of oxygen gas in the star-forming regions around the two galaxies.

    A team of Australian and Spanish astronomers have caught a greedy galaxy gobbling on its neighbours and leaving crumbs of evidence about its dietary past.

    Galaxies grow by churning loose gas from their surroundings into new stars, or by swallowing neighbouring galaxies whole. However, they normally leave very few traces of their cannibalistic habits.

    A study published today in Monthly Notices of the Royal Astronomical Society (MNRAS) not only reveals a spiral galaxy devouring a nearby compact dwarf galaxy, but shows evidence of its past galactic snacks in unprecedented detail.

    Australian Astronomical Observatory (AAO) and Macquarie University astrophysicist, Ángel R. López-Sánchez, and his collaborators have been studying the galaxy NGC 1512 to see if its chemical story matches its physical appearance.

    The team of researchers used the unique capabilities of the 3.9-metre Anglo-Australian Telescope (AAT), near Coonabarabran, New South Wales, to measure the level of chemical enrichment in the gas across the entire face of NGC 1512.

    Anglo Australian Telescope Exterior
    Anglo Australian Telescope Interior
    AAT

    Chemical enrichment occurs when stars churn the hydrogen and helium from the Big Bang into heavier elements through nuclear reactions at their cores. These new elements are released back into space when the stars die, enriching the surrounding gas with chemicals like oxygen, which the team measured.

    “We were expecting to find fresh gas or gas enriched at the same level as that of the galaxy being consumed, but were surprised to find the gases were actually the remnants of galaxies swallowed earlier,” Dr López-Sánchez said.

    “The diffuse gas in the outer regions of NGC 1512 is not the pristine gas created in the Big Bang but is gas that has already been processed by previous generations of stars.”

    CSIRO’s Australia Telescope Compact Array [ATCA], a powerful 6-km diameter radio interferometer located in eastern Australia, was used to detect large amounts of cold hydrogen gas that extends way beyond the stellar disk of the spiral galaxy NGC 1512.

    Australian Telescope Compact Array
    ATCA

    “The dense pockets of hydrogen gas in the outer disk of NGC 1512 accurately pin-point regions of active star formation”, said CSIRO’s Dr Baerbel Koribalski, a member of the research collaboration.

    When this finding was examined in combination with radio and ultraviolet observations the scientists concluded that the rich gas being processed into new stars did not come from the inner regions of the galaxy either. Instead, the gas was likely absorbed by the galaxy over its lifetime as NGC 1512 accreted other, smaller galaxies around it.

    Dr Tobias Westmeier, from the International Centre for Radio Astronomy Research in Perth, said that while galaxy cannibalism has been known for many years, this is the first time that it has been observed in such fine detail.

    “By using observations from both ground and space based telescopes we were able to piece together a detailed history for this galaxy and better understand how interactions and mergers with other galaxies have affected its evolution and the rate at which it formed stars,” he said.

    The team’s successful and novel approach to investigating how galaxies grow is being used in a new program to further refine the best models of galaxy evolution.

    For this work the astronomers used spectroscopic data from the AAT at Siding Spring Observatory in Australia to measure the chemical distribution around the galaxies. They identified the diffuse gas around the dual galaxy system using Australian Telescope Compact Array (ATCA) radio observations. In addition, they identified regions of new star formation with data from the Galaxy Evolution Explorer (GALEX) orbiting space telescope.

    NASA Galex telescope
    NASA/GALEX

    “The unique combination of these data provide a very powerful tool to disentangle the nature and evolution of galaxies,” said Dr López-Sánchez.

    “We will observe several more galaxies using the same proven techniques to improve our understanding of the past behaviour of galaxies in the local Universe.”

    Publication details:

    Á. R. López-Sánchez, T. Westmeier, C. Esteban, and B. S. Koribalski.Ionized gas in the XUV disc of the NGC1512/1510 system. Published in Monthly Notices of the Royal Astronomical Society (MNRAS) through Oxford University Press.

    See the full article here.

    Another view of NGC 1512

    3
    The inner ring of NGC 1512 as imaged by the Hubble Space Telescope (HST). Credit: HST/NASA/ESA.

    NASA Hubble Telescope
    NASA/ESA Hubble

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    ICRAR is an equal joint venture between Curtin University and The University of Western Australia with funding support from the State Government of Western Australia. The Centre’s headquarters are located at UWA, with research nodes at both UWA and the Curtin Institute for Radio Astronomy (CIRA).
    ICRAR has strong support from the government of Australia and is working closely with industry and the astronomy community, including CSIRO and the Australian Telescope National Facility, iVEC, and the international SKA Project Office (SPO), based in the UK.

    ICRAR is:

    Playing a key role in the international Square Kilometre Array (SKA) project, the world’s biggest ground-based telescope array.

    SKA Square Kilometer Array
    Attracting some of the world’s leading researchers in radio astronomy, who will also contribute to national and international scientific and technical programs for SKA and ASKAP.
    Creating a collaborative environment for scientists and engineers to engage and work with industry to produce studies, prototypes and systems linked to the overall scientific success of the SKA, MWA and ASKAP.

    SKA Murchison Widefield Array
    A Small part of the Murchison Widefield Array

    Enhancing Australia’s position in the international SKA program by contributing to the development process for the SKA in scientific, technological and operational areas.
    Promoting scientific, technical, commercial and educational opportunities through public outreach, educational material, training students and collaborative developments with national and international educational organisations.
    Establishing and maintaining a pool of emerging and top-level scientists and technologists in the disciplines related to radio astronomy through appointments and training.
    Making world-class contributions to SKA science, with emphasis on the signature science themes associated with surveys for neutral hydrogen and variable (transient) radio sources.
    Making world-class contributions to SKA capability with respect to developments in the areas of Data Intensive Science and support for the Murchison Radio-astronomy Observatory.

     
  • richardmitnick 5:00 pm on May 21, 2015 Permalink | Reply
    Tags: Astronomy, ,   

    From Hubble: “Hubble Observes One-of-a-Kind Star Nicknamed ‘Nasty'” 

    NASA Hubble Telescope

    Hubble

    May 21, 2015
    Donna Weaver / Ray Villard
    Space Telescope Science Institute, Baltimore, Maryland
    410-338-4493 / 410-338-4514
    dweaver@stsci.edu / villard@stsci.edu

    1
    Object Name: NaSt1, Wolf-Rayet 122, WR 122
    Object Description: Emission-line Star with Nebula
    Instrument: WFC3/UVIS
    Exposure Date(s): April 27, 2013
    Credit: NASA, ESA, and J. Mauerhan (University of California, Berkeley)
    Release Date: May 21, 2015

    Astronomers using NASA’s Hubble Space Telescope have uncovered surprising new clues about a hefty, rapidly aging star whose behavior has never been seen before in our Milky Way galaxy. In fact, the star is so weird that astronomers have nicknamed it “Nasty 1,” a play on its catalog name of NaSt1. The star may represent a brief transitory stage in the evolution of extremely massive stars.

    First discovered several decades ago, Nasty 1 was identified as a Wolf-Rayet star, a rapidly evolving star that is much more massive than our sun. The star loses its hydrogen-filled outer layers quickly, exposing its super-hot and extremely bright helium-burning core.

    But Nasty 1 doesn’t look like a typical Wolf-Rayet star. The astronomers using Hubble had expected to see twin lobes of gas flowing from opposite sides of the star, perhaps similar to those emanating from the massive star Eta Carinae, which is a Wolf-Rayet candidate.

    2
    A huge, billowing pair of gas and dust clouds are captured in this stunning NASA Hubble Space Telescope image of the supermassive star Eta Carinae.

    Instead, Hubble revealed a pancake-shaped disk of gas encircling the star. The vast disk is nearly 2 trillion miles wide, and may have formed from an unseen companion star that snacked on the outer envelope of the newly formed Wolf-Rayet. Based on current estimates, the nebula surrounding the stars is just a few thousand years old, and as close as 3,000 light-years from Earth.

    “We were excited to see this disk-like structure because it may be evidence for a Wolf-Rayet star forming from a binary interaction,” said study leader Jon Mauerhan of the University of California, Berkeley. “There are very few examples in the galaxy of this process in action because this phase is short-lived, perhaps lasting only a hundred thousand years, while the timescale over which a resulting disk is visible could be only ten thousand years or less.”

    According to the team’s scenario, a massive star evolves very quickly, and as it begins to run out of hydrogen, it swells up. Its outer hydrogen envelope becomes more loosely bound and vulnerable to gravitational stripping, or a type of stellar cannibalism, by the nearby companion star. In that process, the more compact star winds up gaining mass, and the original massive star loses its hydrogen envelope, exposing its helium core to become a Wolf-Rayet star.

    Another way Wolf-Rayet stars are said to form is when a massive star ejects its own hydrogen envelope in a strong stellar wind streaming with charged particles. The binary interaction model where a companion star is present is gaining traction because astronomers realize that at least 70 percent of massive stars are members of double-star systems. Direct mass loss alone also cannot account for the number of Wolf-Rayet stars relative to other less-evolved massive stars in the galaxy.

    “We’re finding that it is hard to form all the Wolf-Rayet stars we observe by the traditional wind mechanism, because mass loss isn’t as strong as we used to think,” said Nathan Smith of the University of Arizona in Tucson, who is a co-author on the new NaSt1 paper. “Mass exchange in binary systems seems to be vital to account for Wolf-Rayet stars and the supernovae they make, and catching binary stars in this short-lived phase will help us understand this process.”

    But the mass-transfer process in mammoth binary systems isn’t always efficient. Some of the stripped matter can spill out during the dynamical gravitational tussle between the stars, creating a disk around the binary.

    “That’s what we think is happening in Nasty 1,” Mauerhan said. “We think there is a Wolf-Rayet star buried inside the nebula, and we think the nebula is being created by this mass-transfer process. So this type of sloppy stellar cannibalism actually makes Nasty 1 a rather fitting nickname.”

    The star’s catalog name, NaSt1, is derived from the first two letters of each of the two astronomers who discovered it in 1963, Jason Nassau and Charles Stephenson.

    Viewing the Nasty 1 system hasn’t been easy. The system is so heavily cloaked in gas and dust, it blocks even Hubble’s view of the stars. So Mauerhan’s team cannot measure the mass of each star, the distance between them, or the amount of material spilling onto the companion star.

    Previous observations of Nasty 1 have provided some information on the gas in the disk. The material, for example, is travelling about 22,000 miles per hour in the outer nebula, slower than similar stars. The comparatively slow speed indicates that the star expelled its material through a less violent event than Eta Carinae’s explosive outbursts, where the gas is travelling hundreds of thousands of miles per hour.

    Nasty 1 may also be shedding the material sporadically. Past studies in infrared light have shown evidence for a compact pocket of hot dust very close to the central stars. Recent observations by Mauerhan and colleagues at the University of Arizona, using the Magellan telescope at Las Campanas Observatory in Chile, have resolved a larger pocket of cooler dust that may be indirectly scattering the light from the central stars.

    Magellan 6.5 meter telescopes
    Magellan 6.5 meter Interior
    Magellan Telescope

    The presence of warm dust implies that it formed very recently, perhaps in spurts, as chemically enriched material from the two stellar winds collides at different points, mixes, flows away, and cools. Sporadic changes in the wind strength or the rate the companion star strips the main star’s hydrogen envelope might also explain the clumpy structure and gaps seen farther out in the disk.

    To measure the hypersonic winds from each star, the astronomers turned to NASA’s Chandra X-ray Observatory.

    NASA Chandra Telescope
    Chandra

    The observations revealed scorching hot plasma, indicating that the winds from both stars are indeed colliding, creating high-energy shocks that glow in X-rays. These results are consistent with what astronomers have observed from other Wolf-Rayet systems.

    The chaotic mass-transfer activity will end when the Wolf-Rayet star runs out of material. Eventually, the gas in the disk will dissipate, providing a clear view of the binary system.

    “What evolutionary path the star will take is uncertain, but it will definitely not be boring,” said Mauerhan. “Nasty 1 could evolve into another Eta Carinae-type system. To make that transformation, the mass-gaining companion star could experience a giant eruption because of some instability related to the acquiring of matter from the newly formed Wolf-Rayet. Or, the Wolf-Rayet could explode as a supernova. A stellar merger is another potential outcome, depending on the orbital evolution of the system. The future could be full of all kinds of exotic possibilities depending on whether it blows up or how long the mass transfer occurs, and how long it lives after the mass transfer ceases.”

    The team’s results will appear May 21 in the online edition of the Monthly Notices of the Royal Astronomical Society.

    See the full article here.

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

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  • richardmitnick 4:29 pm on May 21, 2015 Permalink | Reply
    Tags: Astronomy, ,   

    From NASA WISE: “NASA’s WISE Spacecraft Discovers Most Luminous Galaxy in Universe” 

    WISE

    May 21, 2015

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

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

    1

    A remote galaxy shining with the light of more than 300 trillion suns has been discovered using data from NASA’s Wide-field Infrared Survey Explorer (WISE). The galaxy is the most luminous galaxy found to date and belongs to a new class of objects recently discovered by WISE — extremely luminous infrared galaxies, or ELIRGs.

    “We are looking at a very intense phase of galaxy evolution,” said Chao-Wei Tsai of NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, California, lead author of a new report appearing in the May 22 issue of The Astrophysical Journal. “This dazzling light may be from the main growth spurt of the galaxy’s black hole.”

    The brilliant galaxy, known as WISE J224607.57-052635.0, may have a behemoth black hole at its belly, gorging itself on gas. Supermassive black holes draw gas and matter into a disk around them, heating the disk to roaring temperatures of millions of degrees and blasting out high-energy, visible, ultraviolet, and X-ray light. The light is blocked by surrounding cocoons of dust. As the dust heats up, it radiates infrared light.

    Immense black holes are common at the cores of galaxies, but finding one this big so “far back” in the cosmos is rare. Because light from the galaxy hosting the black hole has traveled 12.5 billion years to reach us, astronomers are seeing the object as it was in the distant past. The black hole was already billions of times the mass of our sun when our universe was only a tenth of its present age of 13.8 billion years.

    The new study outlines three reasons why the black holes in the ELIRGs could have grown so massive. First, they may have been born big. In other words, the “seeds,” or embryonic black holes, might be bigger than thought possible.

    “How do you get an elephant?” asked Peter Eisenhardt, project scientist for WISE at JPL and a co-author on the paper. “One way is start with a baby elephant.”

    The other two explanations involve either breaking or bending the theoretical limit of black hole feeding, called the Eddington limit. When a black hole feeds, gas falls in and heats up, blasting out light. The pressure of the light actually pushes the gas away, creating a limit to how fast the black hole can continuously scarf down matter. If a black hole broke this limit, it could theoretically balloon in size at a breakneck pace. Black holes have previously been observed breaking this limit; however, the black hole in the study would have had to repeatedly break the limit to grow this large.

    Alternatively, the black holes might just be bending this limit.

    “Another way for a black hole to grow this big is for it to have gone on a sustained binge, consuming food faster than typically thought possible,” said Tsai. “This can happen if the black hole isn’t spinning that fast.”

    If a black hole spins slowly enough, it won’t repel its meal as much. In the end, a slow-spinning black hole can gobble up more matter than a fast spinner.

    “The massive black holes in ELIRGs could be gorging themselves on more matter for a longer period of time,” said Andrew Blain of University of Leicester in the United Kingdom, a co-author of this report. “It’s like winning a hot-dog-eating contest lasting hundreds of millions of years.”

    More research is needed to solve this puzzle of these dazzlingly luminous galaxies. The team has plans to better determine the masses of the central black holes. Knowing these objects’ true hefts will help reveal their history, as well as that of other galaxies, in this very crucial and frenzied chapter of our cosmos.

    WISE has been finding more of these oddball galaxies in infrared images of the entire sky captured in 2010. By viewing the whole sky with more sensitivity than ever before, WISE has been able to catch rare cosmic specimens that might have been missed otherwise.

    The new study reports a total of 20 new ELIRGs, including the most luminous galaxy found to date. These galaxies were not found earlier because of their distance, and because dust converts their powerful visible light into an incredible outpouring of infrared light.

    “We found in a related study with WISE that as many as half of the most luminous galaxies only show up well in infrared light,” said Tsai.

    The technical paper is online at:

    http://arxiv.org/abs/1410.1751

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    NASA’s Jet Propulsion Laboratory, Pasadena, Calif., manages the Wide-field Infrared Survey Explorer for NASA’s Science Mission Directorate, Washington. The mission’s principal investigator, Edward L. (Ned) Wright, is at UCLA. The mission was competitively selected in 2002 under NASA’s Explorers Program managed by the Goddard Space Flight Center, Greenbelt, Md. The science instrument was built by the Space Dynamics Laboratory, Logan, Utah, and the spacecraft was built by Ball Aerospace & Technologies Corp, Boulder, Colo. Science operations and data processing will take place at the Infrared Processing and Analysis Center at the California Institute of Technology in Pasadena. Caltech manages JPL for NASA.

    The mission’s education and public outreach office is based at the University of California, Berkeley.

     
  • richardmitnick 3:58 pm on May 20, 2015 Permalink | Reply
    Tags: Astronomy, , ,   

    From Carnegie: “Strong UV Pulse Reveals Supernova’s Origin Story” 

    Carnegie Institution for Science
    Carnegie Institution for Science

    May 20, 2015
    No Writer Credit

    1
    An image from a simulation in which a type Ia supernova explodes (as shown in brown). The supernova material is ejected outward at a velocity of about 10,000 kilometers per second and slams into its companion star (as shown in light blue). The collision produces an ultraviolet pulse, which is emitted from the conical hole carved out by the companion star. Image is courtesy of Dan Kasen of University of California Berkeley.

    Type Ia supernovae are violent stellar explosions that shine as some of the brightest objects in the universe. But there are still many mysteries surrounding their origin—what kind of star system they originate in and how the explosions begin. New work from the intermediate Palomar Transient Factory team of astronomers, including Carnegie’s Mansi Kasliwal, provides strong evidence pointing toward one origin theory, called the single degenerate channel. This work is published May 21 by Nature.

    Type Ia supernovae are commonly theorized to be the thermonuclear explosions of a white dwarf star that is part of a binary system—two stars that are physically close and orbit around a common center of mass. But how this white dwarf goes from binary star system to type Ia supernova is a matter of debate.

    The single degenerate channel theory hypothesizes that the white dwarf accretes matter from its companion star and the resulting increase in its central pressure and temperature reaches a tipping point and ignites a thermonuclear explosion. In contrast, the double degenerate theory proposes that the orbit between two white dwarf stars shrinks until the lighter star’s path is disrupted and it moves close enough for some of its matter to be absorbed into the primary white dwarf and initiate an explosion.

    Last May, the iPTF team observed an explosion in the vicinity of a galaxy called IC 831, where no such activity had been seen previously, even the very night before. They called it iPTF14atg. Follow-up observations confirmed that this was indeed a type Ia supernova, one which ignited between May 2 and May 3.

    Looking at the event from Swift space telescope observation records, the team detected bright ultraviolet emission from the new supernova.

    NASA SWIFT Telescope
    NASA/Swift

    “I was examining the first Swift images when suddenly I saw a bright spot at the location of the supernova in the ultraviolet. I jumped up because I knew it was the signature that I had been hoping for,” said Caltech graduate student Yi Cao, lead author of the paper.

    Because ultraviolet radiation is higher energy than visible light, it is particularly suited to observing very hot objects like supernovae. Such an early UV pulse within days of a supernova’s explosion is unprecedented. This strong pulse of emission is consistent with theoretical expectations of collision between material being ejected from a supernova explosion and the companion star from which it has been accreting matter.

    “This provides good evidence that at least some type Ia supernovae arise from the single degenerate channel,” Kasliwal said. “Now we have to determine the fraction of Type Ia that are akin to iPTF14atg.”

    They sought a better understanding of the newly discovered supernova, and particularly of the UV pulse, comparing it to known supernovae in the type Ia family. Their spectroscopic findings with the Apache Point, Gemini, Palomar 200-inch, Nordic Optical Telescope, and Keck observatories indicate that iPTF14atg is a low-velocity type Ia. The team thinks it is likely other low-velocity type Ia supernovae also arose from the single degenerate channel. However, there are other higher-velocity Ia supernovae that likely originate from the double degenerate pathway, as other studies have indicated.

    Apache Point Observatory
    Apache Point Observatory interior
    Apache Point Observatory

    Gemini North telescope
    Gemini North Interior
    Gemini Observatory

    Caltech Palomar 200 inch Hale Telescope
    Caltech Palomar 200 inch Hale Telescope interior
    Palomar 200 inch Telescope

    Nordic Optical Telescope
    Nordic Opitcal Telescope Interior
    Nordic Optical Telescope

    Keck Observatory
    Keck Observatory Interior
    Keck Observatory

    The team’s findings indicate that UV observations of young supernovae could hold the key to fully understanding the pre-explosion interaction between a supernova’s white dwarf progenitor and its companion.

    Other coauthors on the paper are: S. R. Kulkarni of Caltech; D. Andrew Howell, Stefano Valenti of Las Cumbres Observatory Global Telescope Network and University of California Santa Barbara; Avishay Gal-Yam, Assaf Horesh, and Ilan Sagiv of the Weizmann Institute of Science; J. Johansson, R. Amanullah, A. Goobar, J. Sollerman, and F. Taddia of Stockholm University; S. Bradley Cenko and Neil Gehrels of the NASA Goddard Space Flight Center; Peter E. Nugent of Lawrence Berkeley National Laboratory; Iair Arcavi of Las Cumbres Observatory Global Telescope Network and the Kavli Institute for Theoretical Physics; Jason Surace of the Spitzer Science Center at Caltech; P. R.Woźniak and Daniela I. Moody of Los Alamos National Laboratory; Umaa D. Rebbapragada and Brian D. Bue of the Jet Propulsion Laboratory at Caltech.

    Supernova research at the OKC is supported by the Swedish Research Council and by the Knut and Alice Wallenberg Foundation. Some of the data presented here were obtained with the Nordic Optical Telescope, which is operated by the Nordic Optical Telescope Scientific Association at the Observatorio del Roque de los Muchachos, La Palma, Spain. Some of the data presented here were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and NASA. The observatory was made possible by the generous financial support of the W. M. Keck Foundation. This work also makes use of observations from the LCOGT network. Research at California Institute of Technology is supported by the National Science Foundation. LANL participation in iPTF is supported by the US Department of Energy as part of the Laboratory Directed Research and Development program. A portion of this work was carried out at the Jet Propulsion Laboratory under a Research and Technology Development Grant, under contract with the National Aeronautics and Space Administration.

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    Carnegie Institution of Washington Bldg

    Andrew Carnegie established a unique organization dedicated to scientific discovery “to encourage, in the broadest and most liberal manner, investigation, research, and discovery and the application of knowledge to the improvement of mankind…” The philosophy was and is to devote the institution’s resources to “exceptional” individuals so that they can explore the most intriguing scientific questions in an atmosphere of complete freedom. Carnegie and his trustees realized that flexibility and freedom were essential to the institution’s success and that tradition is the foundation of the institution today as it supports research in the Earth, space, and life sciences.

     
  • richardmitnick 8:26 am on May 20, 2015 Permalink | Reply
    Tags: , Astronomy, ,   

    From U Heidelberg: “Asteroid Research Benefits From Gaia Satellite Mission” 

    U Heidelberg bloc

    University of Heidelberg

    20 May 2015
    No Writer Credit

    Scientists discover dozens of small celestial bodies every night

    ESA Gaia satellite
    ESA/Gaia

    Astronomical research on asteroids, i.e. minor planets, is also benefiting from the large-scale Gaia mission of the European Space Agency (ESA). Even though the astrometry satellite’s main purpose is to precisely measure nearly one billion stars in the Milky Way, it has tracked down a multitude of minor planets in our solar system. To determine its current position in space and thus ensure Gaia’s extremely high measurement accuracy, images are taken every day of the regions of the sky where the very faint satellite is located. “Each night the images reveal several dozen minor planets. The data are quite valuable for our understanding of the origin of our solar system,” says Dr. Martin Altmann of the Institute for Astronomical Computing (ARI), which is part of the Centre for Astronomy of Heidelberg University. Dr. Altmann heads the observation programme to determine the position of the Gaia satellite for the Data Processing and Analysis Consortium (DPAC), which is responsible for evaluating the data from Gaia.

    The Gaia astrometry satellite, which has been fully operational since August 2014, measures with pinpoint accuracy the positions, movements and distances of stars in the Milky Way, thereby furnishing the basis for a three-dimensional map of our home galaxy. According to Dr. Altmann, it became clear during preparation for the Gaia mission that the ambitious accuracy goals required novel methods to determine the position and velocity of the satellite itself. For this purpose an observation campaign was launched to determine Gaia’s position and velocity from Earth. As early as 2009, Dr. Altmann of the ARI and his colleague Dr. Sebastien Bouquillon of the Observatoire de Paris (France) began planning the programme together with an international team. Among the partners for the implementation, they attracted observatories in Chile and Spain. The Institute for Astronomical Computing is responsible for coordinating the daily observations. Since the launch of Gaia in December 2013, Gaia’s ground-based position measurements are transmitted regularly to mission control, the European Space Operations Centre in Darmstadt.

    Dr. Altmann explains that the astrometry satellite is at a distance of approximately 1.5 million kilometres and is always located in the region of space away from the Sun as viewed from the Earth. “For this reason Gaia’s positioning images are also perfect for observing minor planets. This so-called oppositional position brings these celestial bodies closer to Earth, making them appear brighter than at other times,” continues the Heidelberg researcher. More than 2,000 small planets have been found this way since the beginning of this year, mainly on images from the VST telescope of the European Southern Observatory (ESO) in Chile.

    ESO VST telescope
    ESO VST

    Dr. Altmann indicates that nearly 40 per cent of them are new discoveries. Moreover, these current measurements are especially interesting for already known minor planets as well, precisely because Gaia and the minor planets located in the same part of space are always opposite the sun at the time of observation. Just like with the full moon, the planets’ entire earthward side is completely illuminated only at that location. This allows the researchers to measure the asteroid’s reflectivity very accurately and draw conclusions as to their chemical composition. Up to now only approximately 30 asteroids have their reflectivity sufficiently well-determined, according to Dr. Altmann.

    The Gaia astrometry satellite itself will also discover and accurately measure many asteroids in its survey of the sky, but in totally different regions. “In this respect, the observations from the Gaia mission and the ground-based measurements complement each other extremely well,” says Dr. Altmann. “We hope not only to acquire new insight into the origins of our home galaxy through the Gaia satellite mission. We will certainly learn more about the origins of our solar system,” stresses Prof. Dr. Stefan Jordan of the Institute for Astronomical Computing, whose responsibilities also include public relations for the DPAC Consortium.

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    U Heidelberg Campus

    Founded in 1386, Heidelberg University, a state university of BadenWürttemberg, is Germany’s oldest university. In continuing its timehonoured tradition as a research university of international standing the Ruprecht-Karls-University’s mission is guided by the following principles:
    Firmly rooted in its history, the University is committed to expanding and disseminating our knowledge about all aspects of humanity and nature through research and education. The University upholds the principle of freedom of research and education, acknowledging its responsibility to humanity, society, and nature.

     
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