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  • richardmitnick 2:51 pm on September 25, 2017 Permalink | Reply
    Tags: , Astronomy, , , , Discovery of Two More Runaway Stars   

    From AAS NOVA: “Discovery of Two More Runaway Stars” 

    AASNOVA

    American Astronomical Society

    25 September 2017
    Susanna Kohler

    1
    Hubble has detected the fastest moving hypervelocity star, even faster than the blue stellar torpedoes caught in 2009. This one moves at 1,600,000mph (2.5 million km/h).

    Speeding stars running away from our galaxy pose an intriguing puzzle: where did these stars come from, and how were they accelerated to their great speeds? The recent discovery of two new runaway stars have increased the mystery.

    Unexplained Speeders

    Hypervelocity stars are rare objects that zip along at unusually high speeds — fast enough to escape the gravitational pull of our galaxy. More than 20 hypervelocity stars have been discovered since the first one was found serendipitously in 2005. But what accelerates these strange stars?

    One of the most commonly proposed scenarios is that these objects originated near the center of the Milky Way, and were flung out as a result of dynamical interactions with the central supermassive black hole. Other explanations exist, however — for instance, these stars could be the tidal debris of an accreted and disrupted dwarf galaxy, or they could be the surviving companion stars kicked out in Type Ia supernovae.

    Besides wanting to better understand the origin of hypervelocity stars, scientists also care about these speedy objects because of the information they provide about the Milky Way. Measuring the three-dimensional motions of hypervelocity stars can give us a detailed look at the mass distribution of our galaxy — thereby revealing the shape of the Milky Way’s dark matter halo.

    2
    The radial velocities and locations of the three LAMOST-detected hypervelocity stars (red), compared to the other 24 known hypervelocity stars (blue). The dashed lines represent two models for the galactic escape velocity curve. [Huang et al. 2017]

    For these reasons, scientists have conducted a number of systematic searches for hypervelocity stars to build up our sample size. Results from the most recent of these searches, conducted by examining the spectroscopic survey data of 6.5 million stars from the Large Sky Area Multi-Object Fibre Spectroscopic Telescope (LAMOST), have now been described in a publication led by Yang Huang (Yunnan University and Peking University).

    LAMOST telescope located in Xinglong Station, Hebei Province, China

    Huang and collaborators narrowed the LAMOST data down to 126 high-mass hypervelocity star candidates. Using distance measurements, they determined the stars’ velocities in the galactic rest frame and eliminated all stars not moving faster than the galactic escape speed. This left three true hypervelocity stars: one that had been previously found in another study, and two that are new discoveries.

    3
    The spatial distribution of the confirmed hypervelocity stars, with the LAMOST detections shown in red and the other 24 known hypervelocity stars shown in blue. The great circles represent planes of young stellar structures near the galactic center. [Huang et al. 2017]

    Conflicting Results

    The authors show that the three detected hypervelocity stars are spatially associated with known young stellar structures near the galactic center, supporting a galactic-center origin for hypervelocity stars. But they also find that the time it would have taken two of these stars to travel to their current locations from the galactic center is longer than the stars’ expected lifetimes, posing a new puzzle.

    Huang and collaborators suggest that upcoming accurate proper motion measurements of these stars, expected in the next data release from the Gaia mission, will provide direct constraints on their origins.

    ESA/GAIA satellite

    In the meantime, continued systematic searches for hypervelocity stars such as that presented here will ensure that we have a large sample of these speeding objects ready for Gaia’s analysis.

    Citation

    Y. Huang et al 2017 ApJL 847 L9. doi:10.3847/2041-8213/aa894b

    See the full article here .

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    AAS Mission and Vision Statement

    The mission of the American Astronomical Society is to enhance and share humanity’s scientific understanding of the Universe.

    The Society, through its publications, disseminates and archives the results of astronomical research. The Society also communicates and explains our understanding of the universe to the public.
    The Society facilitates and strengthens the interactions among members through professional meetings and other means. The Society supports member divisions representing specialized research and astronomical interests.
    The Society represents the goals of its community of members to the nation and the world. The Society also works with other scientific and educational societies to promote the advancement of science.
    The Society, through its members, trains, mentors and supports the next generation of astronomers. The Society supports and promotes increased participation of historically underrepresented groups in astronomy.
    The Society assists its members to develop their skills in the fields of education and public outreach at all levels. The Society promotes broad interest in astronomy, which enhances science literacy and leads many to careers in science and engineering.

    Adopted June 7, 2009

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  • richardmitnick 12:08 pm on September 25, 2017 Permalink | Reply
    Tags: , Astronomy, , , , Counting the Dwarf Galaxies of the Milky Way,   

    From astrobites: “Counting the Dwarf Galaxies of the Milky Way” 

    Astrobites bloc

    Astrobites

    Sep 25, 2017
    Stacy Kim

    Title: The total satellite population of the Milky Way
    Authors: O. Newton, M. Cautum, A. Jenkins, C. S. Frenk and J. C. Helly
    First Author’s Institution: Institute of Computational Cosmology, Durham University, Durham, UK
    1
    Status: Submitted to MNRAS, open access

    Our home galaxy, the Milky Way, is surrounded by small, “dwarf” galaxies. Astronomers are obsessed with counting how many exist. Why? In the 1990s, we realized that the prevailing view of the universe as one primarily composed of dark energy and dark matter, called LCDM for short, predicts that the Milky Way should be surrounded by a vast horde of at least a hundred. But perplexingly, we saw only 11 dwarf galaxies. This stark discrepancy has fueled much consternation and many papers, and has been dubbed the “missing satellites problem.”

    Since then, it’s been recognized that not all satellites found in simulations form bright galaxies that we can detect. The smallest satellites, in particular, can’t hold onto enough cold gas—the material from which stars are born—to form enough stars to make the galaxy detectable. In addition, bigger and better telescopes that scanned wide portions of the sky have turned up more dwarf galaxies. The Sloan Digital Sky Survey (SDSS) found almost 20 new satellites, bringing the total up to about 30.

    SDSS Telescope at Apache Point Observatory, NM, USA

    The ongoing survey called Dark Energy Survey (DES), which surveys the southern skies, has found almost 20 more, and promises to yield more.

    Dark Energy Survey


    Dark Energy Camera [DECam], built at FNAL


    NOAO/CTIO Victor M Blanco 4m Telescope which houses the DECam at Cerro Tololo, Chile, housing DECam at an altitude of 7200 feet

    Additional discoveries by other surveys have pushed the number up to about 55—a drastic increase from the 11 originally known, but still short of 100.

    But the surveys pointed to a solution. Both SDSS and DES only observed part of the sky—SDSS covered about a third, and DES will eventually cover a tenth of the sky—so what if there were more in the regions we hadn’t looked? And while both surveys were powerful, they could only see the faintest dwarfs only if they were close. While the Milky Way is about 300 kiloparsecs in size, we can only see the faintest dwarfs about 30-40 kiloparsecs away from us—only about 0.1% of the entire Milky Way volume. To determine the true number of dwarfs in the Milky Way, the authors of today’s paper attempted to correct for the number we can’t see. This is called a “completeness correction.”

    To do this, the authors turned to the Aquarius Project, a simulation suite with six realizations of the Milky Way, each run with dark matter only and thus without the bright disk of stars and gas that make up the familiar, visible portion of the galaxy (which only makes up about a fifth of the mass of the galaxy, anyway). For each realization, they made a list of all the satellite galaxies they could find. The authors corrected these lists for a couple pieces of physics the simulations did not include. Satellites orbiting the Milky Way are typically stripped of mass due to the Milky Way’s greater gravitational pull. This can cause satellites to drop below the resolution of the simulation, and artificially disappear. The un-simulated disk of the Milky Way can severely strip satellites of mass to the point where they are destroyed. The authors considered how to account for these physics, and carefully added or subtracted satellites to make up for them.

    With the satellite lists in hand, they could finally begin their completeness corrections. For each galaxy we’ve observed with SDSS and DES, the authors determined how much of the Milky Way volume we could see it out to, then asked, “How far down the list of satellites do we need to go before we’d see one in that volume?” After going through each observed galaxy, they got an overall total. The authors repeated this exercise, randomizing the list of simulated satellites each time for each of the 6 simulated Milky Ways in order to determine a reasonable range for the true number of satellites.

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    Figure 1. The number of dwarf galaxies around the Milky Way. The number that’s been observed as a function of how bright the galaxies are is shown by the black dashed line, while the number the authors extrapolated using dwarfs observed in SDSS and DES are shown via the purple line. Extrapolations with only SDSS or only DES dwarfs are shown the dotted blue and green lines, respectively. Figure taken from today’s paper.

    And what did they find? The Milky Way should host about 108-195 total dwarfs. It thus looks like the missing satellites problem might not be so bad after all. With future surveys covering the entire sky, such as the Large Synoptic Survey Telescope coming online soon, we are close to being able to measure—instead of extrapolating—the total number of Milky Way satellites, and determine once and for all whether the missing satellites problem exists.

    LSST


    LSST Camera, built at SLAC



    LSST telescope, currently under construction at Cerro Pachón Chile, a 2,682-meter-high mountain in Coquimbo Region, in northern Chile, alongside the existing Gemini South and Southern Astrophysical Research Telescopes.

    3
    On its way to assembling the most detailed 3D map ever made of our Galaxy, ESA’s Gaia spacecraft has pinned down the precise position on the sky and the brightness of 1.142 billion stars, and in addition measured the velocity and distance of two million of them relative to the Sun. Image credit: ESA / Gaia / DPAC / A. Moitinho & M. Barros, CENTRA – University of Lisbon.

    See the full article here .

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    What do we do?

    Astrobites is a daily astrophysical literature journal written by graduate students in astronomy. Our goal is to present one interesting paper per day in a brief format that is accessible to undergraduate students in the physical sciences who are interested in active research.
    Why read Astrobites?

    Reading a technical paper from an unfamiliar subfield is intimidating. It may not be obvious how the techniques used by the researchers really work or what role the new research plays in answering the bigger questions motivating that field, not to mention the obscure jargon! For most people, it takes years for scientific papers to become meaningful.
    Our goal is to solve this problem, one paper at a time. In 5 minutes a day reading Astrobites, you should not only learn about one interesting piece of current work, but also get a peek at the broader picture of research in a new area of astronomy.

     
  • richardmitnick 11:29 am on September 25, 2017 Permalink | Reply
    Tags: Astronomy, , , , , ,   

    From U Wisconsin IceCube: “Looking for new physics in the neutrino sector” 

    icecube
    U Wisconsin IceCube South Pole Neutrino Observatory

    25 Sep 2017
    Sílvia Bravo

    ICECUBE neutrino detector

    Neutrinos are intriguing in more ways than one. And although the fact that they have such tiny mass explains their quirky behavior, their allure remains intact. The issue is that neutrino masses are not predicted by the Standard Model; thus, on its own, the existence of a neutrino with mass is an indication of new physics. And that’s what scientists around the world, including at IceCube, want to learn: what type of new physics are neutrinos pointing to?

    New physics could appear in the form of a new type of neutrino or it could help us understand the nature of dark matter. The possibilities are endless. In a new search for nonstandard neutrino interactions, the IceCube Collaboration has tested theories that introduce heavy bosons, such as some Grand Unified Theories. These heavy bosons would explain, for example, why neutrinos have masses much smaller than their lepton partners. The study resulted in new constraints on these models, which are among the world’s best limits for nonstandard interactions in the muon-tau neutrino sector. These results have just been submitted to Physical Review D.

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    Confidence limits from this analysis are shown as solid vertical red lines. The light blue and light green vertical lines show previous limits by Super-Kamiokande and another study using IceCube data at higher energy. Credit: IceCube Collaboration.

    Super-Kamiokande experiment. located under Mount Ikeno near the city of Hida, Gifu Prefecture, Japan

    The flavor of neutrinos oscillates as they travel through matter or empty space, a quantum effect on macroscopic scales that proves that they have mass. When atmospheric neutrinos reach IceCube after crossing the Earth, they have often morphed from muon into tau neutrinos. If TeV-scale bosons predicted by nonstandard theories exist, they will modify the probability that a given type of neutrino oscillates into other types. The result is that the disappearance pattern of muon neutrinos in IceCube will change, with effects that span a large range of energies.

    In IceCube, for studies using atmospheric neutrinos that sail through the Earth, these nonstandard interactions (NSIs) can be parametrized in terms of the strength of muon neutrino to tau neutrino morphing due to an NSI, a parameter called .

    IceCube researchers have analyzed three years of data, using the same neutrino sample used for a recent measurement of the neutrino oscillation parameters, but with an additional selection criterion to improve the signal purity. The remaining 4,625 candidate neutrino events were used to fit the oscillation parameters, including the NSI contribution.

    The best fit of muon to tau NSI oscillations was consistent with no nonstandard interactions. “Even though no new physics was shown by this study, it narrows in on the possible existence of new neutrino interactions with regular matter” says Carlos Argüelles, an IceCube researcher from MIT. “It also showcases the advantages of having a very broad energy range, so experiments like IceCube can look for new oscillation physics with neutrinos, which are 10 to 1000 times more energetic than the average proton.”

    The 90% confidence level upper limit on the NSI parameter is consistent with previous measurements by Super-Kamiokande, which at that time had set the world’s best limits. The new IceCube measurement slightly improves Super-Kamiokande’s measurements, also extending the energy range. A more recent study using published IceCube data at even higher energies has also set limits on the parameter, which in turn were slightly more stringent than the ones of the present study.

    Albrecht Karle, a professor of physics at UW–Madison, comments that “the results shown here are based on only a relatively small set of muon neutrinos available.” IceCube is collecting more than 100,000 muon neutrinos per year, which are yet to be mined for physics beyond the Standard Model. “With almost a million atmospheric neutrinos, IceCube has an incredible data set for investigating even small deviations from Standard Model physics.”

    And keeping in mind that it’s not all about the detector, Melanie Day, another IceCube researcher and co-author on this paper, adds, “Not enough is said about the value of teamwork and collaboration over individual contributions to scientific results. But without that, this result would not have been possible.”

    See the full article here .

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    IceCube is a particle detector at the South Pole that records the interactions of a nearly massless sub-atomic particle called the neutrino. IceCube searches for neutrinos from the most violent astrophysical sources: events like exploding stars, gamma ray bursts, and cataclysmic phenomena involving black holes and neutron stars. The IceCube telescope is a powerful tool to search for dark matter, and could reveal the new physical processes associated with the enigmatic origin of the highest energy particles in nature. In addition, exploring the background of neutrinos produced in the atmosphere, IceCube studies the neutrinos themselves; their energies far exceed those produced by accelerator beams. IceCube is the world’s largest neutrino detector, encompassing a cubic kilometer of ice.

     
  • richardmitnick 5:37 am on September 25, 2017 Permalink | Reply
    Tags: Astronomy, , Australian National University, , , New partnership advances Australia’s space mission capabilities, UNSW Canberra   

    From UNSW: “New partnership advances Australia’s space mission capabilities” 

    U NSW bloc

    University of New South Wales

    25 Sep 2017
    Nick Ellis

    A UNSW Canberra agreement with the Australian National University means Australia now has the facilities to come up to speed with the international space sector.

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    UNSW Canberra scientists working on a Cubesat. Photo: UNSW Canberra

    UNSW Canberra and the Australian National University (ANU) will join forces to create end-­to-­end capability for the design, assembly and testing of spacecraft for future space missions.

    The collaboration between the two universities provides joint access to world-­class facilities at UNSW Canberra Space and ANU’s Advanced Instrumentation Technology Centre (AITC).

    UNSW Canberra brings to the agreement its space engineering expertise and Australia’s first Concurrent Design Facility while AITC hosts Australia’s most sophisticated space testing facilities and expertise in spacecraft instrument design and calibration.

    “Australia has been, until now, one of the few developed countries without the ability to professionally design and deliver space missions,” said Professor Russell Boyce, Director of UNSW Canberra Space.

    “The UNSW Canberra team includes 40 highly skilled Australian space professionals from the global space sector. This includes scientists, engineers, faculty staff, postdocs and PhD students, who bring more than 150 years of experience in organisations such as ESA and NASA –­ where they designed, developed and deployed spacecraft and space instrumentation for near-­Earth and deep space programs.”

    Dr Doug Griffin, Space Mission Lead at UNSW Canberra Space, said: “Space is a big industry, it is complicated and requires a diverse, yet unique set of skills. The UNSW Canberra agreement with ANU means Australia now has the facilities to come up to speed with the international space sector.”

    UNSW Canberra’s new Concurrent Design Facility, partly funded by the ACT Government, will also partner with the French space agency CNES. An Australian first, this facility allows the country to lead the design and operation of future space missions.

    “This is an exciting time for Australian space research and innovation,” said Professor Michael Frater, Rector of UNSW Canberra. “The combination of two Group of 8 universities in the heart of the nation’s capital, focussing on space missions, will see the ACT and Australia mature as serious players on the global space stage.”

    UNSW Canberra Space already provides valuable research and technology to support national services, including Defence. UNSW Canberra’s space program, with five satellites now confirmed, demonstrates what can be done in Australia.

    Professor Boyce said: “This agreement also helps create the right environment in the ACT for space engineering to grow and deliver commercial operations. The UNSW Canberra commercial spin-­off Skykraft will provide commercial services to a growing space sector, drawing on the research at UNSW Canberra Space.

    “So, our UNSW Canberra space partnerships will service not only our teaching and research, but will feed right through to supporting national needs and commercial opportunities.

    “These agreements provide new employment pathways for university graduates, while positioning Canberra right at the heart of the national space industry.”

    See the full article here .

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    U NSW Campus

    Welcome to UNSW Australia (The University of New South Wales), one of Australia’s leading research and teaching universities. At UNSW, we take pride in the broad range and high quality of our teaching programs. Our teaching gains strength and currency from our research activities, strong industry links and our international nature; UNSW has a strong regional and global engagement.

    In developing new ideas and promoting lasting knowledge we are creating an academic environment where outstanding students and scholars from around the world can be inspired to excel in their programs of study and research. Partnerships with both local and global communities allow UNSW to share knowledge, debate and research outcomes. UNSW’s public events include concert performances, open days and public forums on issues such as the environment, healthcare and global politics. We encourage you to explore the UNSW website so you can find out more about what we do.

     
  • richardmitnick 4:50 am on September 25, 2017 Permalink | Reply
    Tags: Astronomy, , , , CSIROblog, MPIFR/Effelsberg Radio Telescope, ,   

    From CSIROblog: “German telescope wears Aussie tech” 

    CSIRO bloc

    CSIRO blog

    25 September 2017
    Helen Sim

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    We designed and built a sophisticated receiver for Germany’s Effelsberg telescope. No image credit.

    MPIFR/Effelsberg Radio Telescope, in the Ahrgebirge (part of the Eifel) in Bad Münstereifel, Germany

    German engineering is renowned. Our Parkes radio telescope was built by a German firm, MAN (Maschinenfabrik Augsburg–Nürnberg).

    CSIRO/Parkes Observatory, located 20 kilometres north of the town of Parkes, New South Wales, Australia

    Now our astronomy technology is boosting the performance of Germany’s flagship radio telescope.

    We’ve provided a sophisticated radio receiver called a ‘phased array feed’ or ‘PAF’ for the Effelsberg telescope. At 100 m in diameter, Effelsberg is a tad bigger than Parkes and the biggest single-dish telescope in Europe.

    Although we designed PAFs for our new ASKAP telescope in Western Australia, which is an array of 36 dishes, it turns out they’re pretty handy for single dishes too.

    1

    Before we shipped the customised PAF to Germany we put it on the Parkes telescope for a few months to see how it performed on a big dish. The answer was, very well indeed.

    The PAF could detect one of the fundamental components of the Universe, atomic hydrogen, much further away than we usually can. And it let astronomers cut out a lot of pesky radio interference – unwanted radio signals arising from human activities.

    The tests were led by scientists from the International Centre for Radio Astronomy Research in Perth, Western Australia. One of them, Professor Lister Staveley-Smith, is leading a bid to fund a special cooled PAF to use on Parkes long-term. That cooled PAF would do some pretty cool science, like looking for signs of exotic matter called ‘positronium’.

    When the Parkes tests were over we took the PAF to the airport and sent it on its way to Effelsberg’s operator, the Max Planck Institute for Radio Astronomy. In its new home it’ll be searching for fast radio bursts, the still-mysterious radio signals from the distant Universe.

    In other applications, phased-array feeds could also be used to observe Earth from space and for other kinds of imaging.

    You can see our PAF technology at the Adelaide Convention Centre from 25 to 29 September 2017, on the Australian Government stand at the International Astronautical Congress.

    See the full article here .

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    CSIRO campus

    CSIRO, the Commonwealth Scientific and Industrial Research Organisation, is Australia’s national science agency and one of the largest and most diverse research agencies in the world.

    The CSIRO blog is designed to entertain, inform and inspire by generally digging around in the work being done by our terrific scientists, and leaving the techie speak and jargon for the experts.

    We aim to bring you stories from across the vast breadth and depth of our organisation: from the wild sea voyages of our Research Vessel Investigator to the mind-blowing astronomy of our Space teams, right through all the different ways our scientists solve national challenges in areas as diverse as Health, Farming, Tech, Manufacturing, Energy, Oceans, and our Environment.

    If you have any questions about anything you find on our blog, we’d love to hear from you. You can reach us at socialmedia@csiro.au.

    And if you’d like to find out more about us, our science, or how to work with us, head over to CSIRO.au

     
  • richardmitnick 1:19 pm on September 24, 2017 Permalink | Reply
    Tags: , Astronomy, , , , ,   

    From Futurism: “Stephen Hawking Has Flawed Ideas About Alien Life, According to Former SETI Scientist” 

    futurism-bloc

    Futurism

    September 24, 2017
    Christianna Reedy

    Calling All Aliens

    As autumn brings with it cooler temperatures and clearer night skies, Douglas Vakoch, president of Messaging Extraterrestrial Intelligence (METI), wants you to take the opportunity to survey the glory of our galaxy — and to contemplate the existence of alien life.

    METI (Messaging Extraterrestrial Intelligence) International has announced plans to start sending signals into space

    “You look at the night sky — virtually all of those stars have planets,” Rosenberg said in an exclusive interview with Futurism. “Maybe one out of five has it at just the right zone where there’s liquid water. And so we know there are a lot of places that there could be life. Now the big question is, are they actually trying to make contact, or do they want us to try?”

    METI’s stance is that we should assume the latter, and the collection of scientists have taken it upon themselves to reach out to any potential alien civilizations. In fact, the next transmission planned for next year. However, there have long been voices opposed to this strategy — perhaps the most prominent of which being Stephen Hawking.

    Hawking, a noted physicist and author, supports the search for aliens, but regularly cautions against attempting contact. Hawking argued in “Stephen Hawking’s Favorite Places,” a video on the platform CuriosityStream, that aliens could be “vastly more powerful and may not see us as any more valuable than we see bacteria.”

    Paying Our Dues?

    These are not warnings that Vakoch takes lightly. “Well, when Stephen Hawking, a brilliant cosmologist, has said, ‘whatever you do, don’t transmit, we don’t want the aliens to come to Earth,’ You’ve got to take it seriously,” Vakoch told Futurism.

    But there’s one key point that Hawking really doesn’t seem to take into consideration in this assessment, Vakoch said.

    “It’s the fact that every civilization that does have the ability to travel to Earth could already pick up I Love Lucy. So we have been sending our existence into space with radio signals for 78 years. Even before that, two and a half billion years, we have been telling the Universe that there is life on here because of the oxygen in our atmosphere. So if there’s any alien out there paranoid about competition, it could have already come and wipe us out. If they’re on their way, it’s a lot better strategy to say we’re interested in being conversational partners. Let’s strike up a new conversation.”

    It’s Vakoch’s belief that humanity’s first contact with alien life will occur within our lifetimes. But even if it does not, he believes the METI project will be foundational to any relationship our world builds with others.

    “Sometimes people talk about this interstellar communication as an effort to join the galactic club. What I find so strange is no one ever talks about paying our dues or even submitting an application. And that’s what METI does,” Vakoch said. “It’s actually contributing something to the galaxy instead of saying gimme gimme gimme me. What can we do for someone else.”

    See the full article here .

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    Futurism covers the breakthrough technologies and scientific discoveries that will shape humanity’s future. Our mission is to empower our readers and drive the development of these transformative technologies towards maximizing human potential.

     
  • richardmitnick 7:26 am on September 24, 2017 Permalink | Reply
    Tags: Astronomy, , , , , We are Stardust   

    From NRAO: We are Stardust 

    NRAO Icon
    National Radio Astronomy Observatory

    NRAO Banner

    See the full article here .

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    NRAO/Karl V Jansky VLA, on the Plains of San Agustin fifty miles west of Socorro, NM, USA

    The NRAO operates a complementary, state-of-the-art suite of radio telescope facilities for use by the scientific community, regardless of institutional or national affiliation: the Very Large Array (VLA), and the Very Long Baseline Array (VLBA)*.

    ESO/NRAO/NAOJ ALMA Array in Chile in the Atacama at Chajnantor plateau, at 5,000 metres

    Access to ALMA observing time by the North American astronomical community will be through the North American ALMA Science Center (NAASC).

    NRAO VLBA

    NRAO VLBA

    *The Very Long Baseline Array (VLBA) comprises ten radio telescopes spanning 5,351 miles. It’s the world’s largest, sharpest, dedicated telescope array. With an eye this sharp, you could be in Los Angeles and clearly read a street sign in New York City!

    Astronomers use the continent-sized VLBA to zoom in on objects that shine brightly in radio waves, long-wavelength light that’s well below infrared on the spectrum. They observe blazars, quasars, black holes, and stars in every stage of the stellar life cycle. They plot pulsars, exoplanets, and masers, and track asteroids and planets.

    And the future Expanded Very Large Array (EVLA).

     
  • richardmitnick 7:15 am on September 24, 2017 Permalink | Reply
    Tags: Astronomy, , , ,   

    From NASA on tumblr: “A Wider Set of Eyes on the Universe” 

    NASA image
    NASA

    After years of preparatory studies, we are formally starting an astrophysics mission designed to help unlock the secrets of the universe.
    Introducing…
    the Wide Field Infrared Survey Telescope, aka WFIRST.

    1
    With a view 100 times bigger than that of our Hubble Space Telescope, WFIRST will help unravel the secrets of dark energy and dark matter, and explore the evolution of the cosmos. It will also help us discover new worlds and advance the search for planets suitable for life.

    WFIRST is slated to launch in the mid-2020s. The observatory will begin operations after traveling about one million miles from Earth, in a direction directly opposite the sun.

    2
    Telescopes usually come in two different “flavors” – you have really big, powerful telescopes, but those telescopes only see a tiny part of the sky. Or, telescopes are smaller and so they lack that power, but they can see big parts of the sky. WFIRST is the best of worlds.

    No matter how good a telescope you build, it’s always going to have some residual errors. WFIRST will be the first time that we’re going to fly an instrument that contains special mirrors that will allow us to correct for errors in the telescope. This has never been done in space before!


    Employing multiple techniques, astronomers will also use WFIRST to track how dark energy and dark matter have affected the evolution of our universe. Dark energy is a mysterious, negative pressure that has been speeding up the expansion of the universe. Dark matter is invisible material that makes up most of the matter in our universe.

    Single WFIRST images will contain over a million galaxies! We can’t categorize and catalogue those galaxies on our own, which is where citizen science comes in. This allows interested people in the general public to solve scientific problems.

    See the full article here .

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    The National Aeronautics and Space Administration (NASA) is the agency of the United States government that is responsible for the nation’s civilian space program and for aeronautics and aerospace research.

    President Dwight D. Eisenhower established the National Aeronautics and Space Administration (NASA) in 1958 with a distinctly civilian (rather than military) orientation encouraging peaceful applications in space science. The National Aeronautics and Space Act was passed on July 29, 1958, disestablishing NASA’s predecessor, the National Advisory Committee for Aeronautics (NACA). The new agency became operational on October 1, 1958.

    Since that time, most U.S. space exploration efforts have been led by NASA, including the Apollo moon-landing missions, the Skylab space station, and later the Space Shuttle. Currently, NASA is supporting the International Space Station and is overseeing the development of the Orion Multi-Purpose Crew Vehicle and Commercial Crew vehicles. The agency is also responsible for the Launch Services Program (LSP) which provides oversight of launch operations and countdown management for unmanned NASA launches. Most recently, NASA announced a new Space Launch System that it said would take the agency’s astronauts farther into space than ever before and lay the cornerstone for future human space exploration efforts by the U.S.

    NASA science is focused on better understanding Earth through the Earth Observing System, advancing heliophysics through the efforts of the Science Mission Directorate’s Heliophysics Research Program, exploring bodies throughout the Solar System with advanced robotic missions such as New Horizons, and researching astrophysics topics, such as the Big Bang, through the Great Observatories [Hubble, Chandra, Spitzer, and associated programs. NASA shares data with various national and international organizations such as from the [JAXA]Greenhouse Gases Observing Satellite.

     
  • richardmitnick 6:55 am on September 24, 2017 Permalink | Reply
    Tags: Astronomy, , , Black Hole Sculpts an Hourglass Galaxy, , NASA on tumblr   

    From NASA: “NASA on Tumblr – Black Hole Sculpts an Hourglass Galaxy” 

    NASA image
    NASA

    Black Hole Sculpts an Hourglass Galaxy

    When it comes to galaxies, our home, the Milky Way, is rather neat and orderly. Other galaxies can be much more chaotic. For example, the Markarian 573 galaxy has a black hole at its center which is spewing beams of light in opposite directions, giving its inner regions more of an hourglass shape.

    1

    Our scientists have long been fascinated by this unusual structure, seen above in optical light from the Hubble Space Telescope. Now their search has taken them deeper than ever — all the way into the super-sized black hole at the center of one galaxy.

    So, what do we think is going on? When the black hole gobbles up matter, it releases a form of high-energy light called radiation (particularly in the form of X-rays), causing abnormal patterns in the flow of gas.

    Let’s take a closer look.

    Meet Markarian 573, the galaxy at the center of this image from the Sloan Digital Sky Survey, located about 240 million light-years away from Earth in the constellation Cetus. It’s the galaxy’s odd structure and the unusual motions of its components that inspire our scientists to study it.

    2

    SDSS Telescope at Apache Point Observatory, NM, USA

    3
    As is the case with other so-called active galaxies, the ginormous black hole at the center of Markarian 573 likes to eat stuff. A thick ring of dust and gas accumulates around it, forming a doughnut. This ring only permits light to escape the black hole in two cone-shaped regions within the flat plane of the galaxy — and that’s what creates the hourglass, as shown in the illustration above.

    4
    Zooming out, we can see the two cones of emission (shown in gold in the animation above) spill into the galaxy’s spiral arms (blue). As the galaxy rotates, gas clouds in the arms sweep through this radiation, which makes them light up so our scientists can track their movements from Earth.

    5
    What happens next depends on how close the gas is to the black hole. Gas that’s about 2,500 light-years from the black hole picks up speed and streams outward (shown as darker red and blue arrows). Gas that’s farther from the black hole also becomes ionized, but is not driven away and continues its motion around the galaxy as before.

    6
    Here is an actual snapshot of the inner region of Markarian 573, combining X-ray data (blue) from our Chandra X-ray Observatory and radio observations (purple) from the Karl G. Jansky Very Large Array in New Mexico with a visible light image (gold) from our Hubble Space Telescope. Given its strange appearance, we’re left to wonder: what other funky shapes might far-off galaxies take?

    For more information about the bizarre structure of Markarian 573, visit http://svs.gsfc.nasa.gov/12657

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    The National Aeronautics and Space Administration (NASA) is the agency of the United States government that is responsible for the nation’s civilian space program and for aeronautics and aerospace research.

    President Dwight D. Eisenhower established the National Aeronautics and Space Administration (NASA) in 1958 with a distinctly civilian (rather than military) orientation encouraging peaceful applications in space science. The National Aeronautics and Space Act was passed on July 29, 1958, disestablishing NASA’s predecessor, the National Advisory Committee for Aeronautics (NACA). The new agency became operational on October 1, 1958.

    Since that time, most U.S. space exploration efforts have been led by NASA, including the Apollo moon-landing missions, the Skylab space station, and later the Space Shuttle. Currently, NASA is supporting the International Space Station and is overseeing the development of the Orion Multi-Purpose Crew Vehicle and Commercial Crew vehicles. The agency is also responsible for the Launch Services Program (LSP) which provides oversight of launch operations and countdown management for unmanned NASA launches. Most recently, NASA announced a new Space Launch System that it said would take the agency’s astronauts farther into space than ever before and lay the cornerstone for future human space exploration efforts by the U.S.

    NASA science is focused on better understanding Earth through the Earth Observing System, advancing heliophysics through the efforts of the Science Mission Directorate’s Heliophysics Research Program, exploring bodies throughout the Solar System with advanced robotic missions such as New Horizons, and researching astrophysics topics, such as the Big Bang, through the Great Observatories [Hubble, Chandra, Spitzer, and associated programs. NASA shares data with various national and international organizations such as from the [JAXA]Greenhouse Gases Observing Satellite.

     
  • richardmitnick 4:41 pm on September 22, 2017 Permalink | Reply
    Tags: , Astronomy, , , , When a Star and a Binary Meet   

    From AAS NOVA: ” When a Star and a Binary Meet” 

    AASNOVA

    American Astronomical Society

    22 September 2017
    Susanna Kohler

    1
    What happens when stars interact in dense environments, such as globular clusters like the one pictured here? [HST/NASA/ESA]

    What happens in the extreme environments of globular clusters when a star and a binary system meet? A team of scientists has new ideas about how these objects can deform, change their paths, spiral around each other, and merge.

    Getting to Know Your Neighbors

    2
    Two simulations of the interaction of a white-dwarf–compact-object binary with a single incoming compact object (progressing from left to right). When tides are not included (bottom panel), the system interacts chaotically for a while before the single compact object is ejected and the binary system leaves on slightly modified orbit. When tides are included (top panel), the chaotic interactions eventually result in the tidal inspiral and merger of the binary (labeled in the top diagram and shown in detail in the inset). [Samsing et al. 2017]

    Stars living in dense environments, like globular clusters, experience very different lives than those in the solar neighborhood. In these extreme environments, close encounters are the norm — and this can lead to a variety of interesting interactions between the stars and systems of stars that encounter each other.

    One common type of meeting is that of a single star with a binary star system. Studies of such interactions often treat all three bodies like point sources, examining outcomes like:

    1. All three objects are mutually unbound by the interaction, resulting in three single objects.
    2. A flyby encounter occurs, in which the binary survives the encounter but its orbit becomes modified by the third star.
    3. An exchange occurs, in which the single star swaps spots with one of the binary stars and ejects it from the system.

    Complexities of Extended Objects

    But what if you treat the bodies not like point sources, but like extended objects with actual radii (as is true in real life)? Then there are additional complexities, such as collisions when the stars’ radii overlap, general relativistic effects when the stars pass very near one another, and tidal oscillations as gravitational forces stretch the stars out during a close passage and then release afterward.

    In a recently published study led by Johan Samsing (an Einstein Fellow at Princeton University), the authors explore how these complexities change the behavior of binary-single interactions in the centers of dense star clusters.

    3
    One example — again in the case of a white-dwarf–compact-object binary interacting with a single compact object — of the cross sections for different types of interactions. Exchanges (triangles) are generally most common, and direct collisions (circles) occur frequently, but tidal inspirals (pluses) can occur with similar frequency in such systems. Inspirals due to energy loss to gravitational waves (crosses) can occur as well. [Samsing et al. 2017]

    How Tides Change Things

    Using numerical simulations with an N-body code, and following up with analytic arguments, Samsing and collaborators show that the biggest change when they include effects such as tides is a new outcome that sometimes results from the chaotic evolution of the triple interaction: tidal inspirals.

    Tidal inspirals occur when a close passage creates tidal oscillations in a star, draining energy from the binary orbit. Under the right conditions, the loss of energy will lead to the stars’ inspiral, eventually resulting in a merger. This new channel for mergers — similar to mergers due to energy lost to gravitational waves — can occur even more frequently than collisions in some systems.

    Samsing and collaborators demonstrate that tidal inspirals occur more commonly for widely separated binaries and small-radius objects. Highly eccentric white-dwarf–neutron-star mergers, for example, can be dominated by tidal inspirals.

    The authors point out that this interesting population of eccentric compact binaries likely results in unique electromagnetic and gravitational-wave signatures — which suggests that further studies of these systems are important for better understanding what we can expect to observe when stars encounter each other in dense stellar systems.
    Citation

    Johan Samsing et al 2017 ApJ 846 36. doi:10.3847/1538-4357/aa7e32

    Related Journal Articles
    Further references at the full article with links.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    1

    AAS Mission and Vision Statement

    The mission of the American Astronomical Society is to enhance and share humanity’s scientific understanding of the Universe.

    The Society, through its publications, disseminates and archives the results of astronomical research. The Society also communicates and explains our understanding of the universe to the public.
    The Society facilitates and strengthens the interactions among members through professional meetings and other means. The Society supports member divisions representing specialized research and astronomical interests.
    The Society represents the goals of its community of members to the nation and the world. The Society also works with other scientific and educational societies to promote the advancement of science.
    The Society, through its members, trains, mentors and supports the next generation of astronomers. The Society supports and promotes increased participation of historically underrepresented groups in astronomy.
    The Society assists its members to develop their skills in the fields of education and public outreach at all levels. The Society promotes broad interest in astronomy, which enhances science literacy and leads many to careers in science and engineering.

    Adopted June 7, 2009

     
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