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  • richardmitnick 8:01 am on March 25, 2017 Permalink | Reply
    Tags: , Astrophysics, , Birkeland currents, , , Our atmosphere, U Calgary   

    From ESA: Supersonic Plasma Jets Discovered 

    ESA Space For Europe Banner

    European Space Agency

    23 March 2017
    No writer credit

    Information from ESA’s magnetic field Swarm mission has led to the discovery of supersonic plasma jets high up in our atmosphere that can push temperatures up to almost 10 000°C.

    Presenting these findings at this week’s Swarm Science Meeting in Canada, scientists from the University of Calgary explained how they used measurements from the trio of Swarm satellites to build on what was known about vast sheets of electric current in the upper atmosphere.

    The theory that there are huge electric currents, powered by solar wind and guided through the ionosphere by Earth’s magnetic field, was postulated more than a century ago by Norwegian scientist Kristian Birkeland.

    1
    Birkeland currents
    Released 23/03/2017 10:19 am
    Copyright University of Calgary/ESA
    Description

    ESA’s Swarm has been used to improve our understanding about vast sheets of electric current in the upper atmosphere. Birkeland currents carry up to 1 TW of electric power to the upper atmosphere – about 30 times the energy consumed in New York during a heatwave. They are also responsible for ‘aurora arcs’, the familiar, slow-moving green curtains of light that can extend from horizon to horizon.
    Recent observations by Swarm have revealed that they are associated with large electrical fields and occur where upwards and downwards Birkeland currents connect through the ionosphere. Scientists have also discovered that these strong electric fields drive supersonic plasma jets.

    2
    Upward and downward current sheets
    Released 23/03/2017 10:10 am
    Copyright University of Calgary/ESA
    Description
    Birkeland currents carry up to 1 TW of electric power to the upper atmosphere – about 30 times the energy consumed in New York during a heatwave. They are also responsible for ‘aurora arcs’, the familiar, slow-moving green curtains of light that can extend from horizon to horizon. Recent observations by Swarm have revealed that they are associated with large electrical fields and occur where upwards and downwards Birkeland currents connect through the ionosphere. Scientists have also discovered that these strong electric fields drive supersonic plasma jets.

    It wasn’t until the 1970s, after the advent of satellites, however, that these ‘Birkeland currents’ were confirmed by direct measurements in space. These currents carry up to 1 TW of electric power to the upper atmosphere – about 30 times the energy consumed in New York during a heatwave. They are also responsible for ‘aurora arcs’, the familiar, slow-moving green curtains of light that can extend from horizon to horizon. While much is known about these current systems, recent observations by Swarm have revealed that they are associated with large electrical fields.

    These fields, which are strongest in the winter, occur where upwards and downwards Birkeland currents connect through the ionosphere.

    Bill Archer from the University of Calgary explained, “Using data from the Swarm satellites’ electric field instruments, we discovered that these strong electric fields drive supersonic plasma jets.

    “The jets, which we call ‘Birkeland current boundary flows’, mark distinctly the boundary between current sheets moving in opposite direction and lead to extreme conditions in the upper atmosphere.

    “They can drive the ionosphere to temperatures approaching 10 000°C and change its chemical composition. They also cause the ionosphere to flow upwards to higher altitudes where additional energisation can lead to loss of atmospheric material to space.”

    4
    Magnetic field sources
    Released 31/10/2012 4:35 pm
    Copyright ESA/DTU Space
    The different sources that contribute to the magnetic field measured by Swarm. The coupling currents or field-aligned currents flow along magnetic field lines between the magnetosphere and ionosphere.

    David Knudsen, also from the University of Calgary, added, “These recent findings from Swarm add knowledge of electric potential, and therefore voltage, to our understanding of the Birkeland current circuit, perhaps the most widely recognised organising feature of the coupled magnetosphere–ionosphere system.”

    This discovery is just one of the new findings presented at the week-long science meeting dedicated to the Swarm mission. Also presented this week and focusing on Birkeland currents, for example, Swarm was used to confirm that these currents are stronger in the northern hemisphere and vary with the season.

    Since they were launched in 2013, the identical Swarm satellites have been measuring and untangling the different magnetic signals that stem from Earth’s core, mantle, crust, oceans, ionosphere and magnetosphere.

    5
    Front of Swarm satellite
    Released 04/02/2014 5:07 pm
    Copyright ESA/ATG medialab
    Swarm is ESA’s first Earth observation constellation of satellites. The trio of identical satellites are designed to identify and measure precisely the different magnetic signals that make up Earth’s magnetic field. The electrical field instrument, positioned at the front of each satellite, measures plasma density, drift and acceleration in high resolution to characterise the electric field around Earth.

    As well as a package of instruments to do this, each satellite has an electric field instrument positioned at the front to measure plasma density, drift and velocity.

    Rune Floberghagen, ESA’s Swarm mission manager, said, “The electric field instrument is the first ionospheric imager in orbit so it’s very exciting to see such fantastic results that are thanks to this new instrument.

    “The dedication of scientists working with data from the mission never ceases to amaze me and we are seeing some brilliant results, such as this, discussed at this week’s meeting.

    “Swarm is really opening our eyes to the workings of the planet from deep down in Earth’s core to the highest part of our atmosphere.”

    See the full article here .

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    The European Space Agency (ESA), established in 1975, is an intergovernmental organization dedicated to the exploration of space, currently with 19 member states. Headquartered in Paris, ESA has a staff of more than 2,000. ESA’s space flight program includes human spaceflight, mainly through the participation in the International Space Station program, the launch and operations of unmanned exploration missions to other planets and the Moon, Earth observation, science, telecommunication as well as maintaining a major spaceport, the Guiana Space Centre at Kourou, French Guiana, and designing launch vehicles. ESA science missions are based at ESTEC in Noordwijk, Netherlands, Earth Observation missions at ESRIN in Frascati, Italy, ESA Mission Control (ESOC) is in Darmstadt, Germany, the European Astronaut Centre (EAC) that trains astronauts for future missions is situated in Cologne, Germany, and the European Space Astronomy Centre is located in Villanueva de la Cañada, Spain.

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  • richardmitnick 2:39 pm on March 24, 2017 Permalink | Reply
    Tags: , Astrophysics, , , , , , ,   

    From WIRED: “Astronomers Don’t Point This Telescope—The Telescope Points Them” 

    Wired logo

    WIRED

    03.23.17
    Sarah Scoles

    1
    U Texas Austin McDonald Observatory Hobby-Eberly Telescope

    The hills of West Texas rise in waves around the Hobby-Eberly Telescope, a powerful instrument encased in a dome that looks like the Epcot ball. Soon, it will become more powerful still: Scientists recently primed the telescope to find evidence of dark energy in the early universe, prying open its eye so it can see and process a wide swath of sky. On April 8, scientists will dedicate the new telescope, capping off the $40 million upgrade and beginning the real work.

    The dark energy experiment, called Hetdex, isn’t how astronomy has traditionally been done. In the classical model, a lone astronomer goes to a mountaintop and solemnly points a telescope at one predetermined object. But Hetdex won’t look for any objects in particular; it will just scan the sky and churn petabytes of the resulting data through a silicon visual cortex. That’s only possible because of today’s steroidal computers, which let scientists analyze, store, and send such massive quantities of data.

    “Dark energy is not only terribly important for astronomy, it’s the central problem for physics. It’s been the bone in our throat for a long time.”

    Steven Weinberg
    Nobel Laureate
    University of Texas at Austin

    The hope is so-called blind surveys like this one will find stuff astronomers never even knew to look for. In this realm, computers take over curation of the sky, telling astronomers what is interesting and worthy of further study, rather than the other way around. These wide-eyed projects are becoming a standard part of astronomers’ arsenal, and the greatest part about them is that their best discoveries are still totally TBD.

    Big Sky Country

    To understand dark energy—that mysterious stuff that pulls the taffy of spacetime—the Hetdex team needed Hobby-Eberly to study one million galaxies 9-11 billion light-years away as they fly away from Earth. To get that many galaxies in a reasonable amount of time, they broadened the view of its 91 tessellated stop-sign-shaped mirrors by 100. They also created an instrument called Virus, with 35,000 optical fibers that send the light from the universe to a spectrograph, which splits it up into constituent wavelengths. All that data can determine both how far away a galaxy is and how fast it’s traveling away from Earth.

    But when a telescope takes a ton of data down from the sky, scientists can also uncover the unexpected. Hetdex’s astronomers will find more than just the stretch marks of dark energy. They’ll discover things about supermassive black holes, star formation, dark matter, and the ages of stars in nearby galaxies.

    The classical method still has advantages; if you know exactly what you want to look at, you write up a nice proposal to Hubble and explain why a fixed gaze at the Whirlpool Galaxy would yield significant results. “But what you see is what you get,” says astronomer Douglas Hudgins. “This is an object, and the science of that object is what you’re stuck with.”

    See the full article here .

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  • richardmitnick 1:20 pm on March 24, 2017 Permalink | Reply
    Tags: , , Astrophysics, , Challenging the Model for Galactic Bulges, , Galactic bulges   

    From AAS NOVA: “Challenging the Model for Galactic Bulges” 

    AASNOVA

    American Astronomical Society

    24 March 2017
    Susanna Kohler

    1
    The Sombrero Galaxy (Messier 104), an example of a galaxy with a large, classical central bulge. A recent study examines how bulges might grow in the centers of galaxies similar to our own. [ESO]

    Galaxies of similar stellar mass to our own don’t all have the same bulge and black hole masses. So what determines how much mass will end up in the bulge and the black hole at the center of a Milky-Way-like galaxy?

    The Role of Mergers

    One theory is that major and minor mergers build up the bulge and black-hole masses for some galaxies. It’s often argued that massive, centrally concentrated “classical” bulges are caused by merger activity, whereas less massive, more disk-like “pseudobulges” might be caused by other means, such as violent disk instabilities in early gas-rich disks, or misaligned infall of gas throughout cosmic time.

    2
    Bulge mass (top) and BH mass (bottom) as a function of stellar halo mass. Red denotes galaxies with low-mass pseudobulges, black shows galaxies with higher-mass classical bulges. The grey shaded area in the bottom plot shows what would be expected if there were a 1:1 correlation between bulge mass and stellar halo mass. [Bell et al. 2017]

    A team of scientists led by Eric Bell (University of Michigan) set out to test the role of major and minor mergers in bulge formation by examining the stellar halos of a sample of 18 Milky-Way-mass galaxies — six with classical bulges expected to have grown through mergers and 12 with pseudobulges expected to have grown through a variety of other mechanisms.

    Halos as Historical Record

    Stellar halos offer a useful way of tracking the merger history of a galaxy. It’s believed that as major mergers with larger satellites occur, a galaxy’s stellar halo will increase in both mass and metallicity as it retains the stars of the satellite.

    Bell and collaborators first verify this picture in their sample by plotting the stellar halo metallicities against the stellar halo masses. This check reveals a strong correlation between the two properties that’s consistent with the outcomes from simulations — so the stellar halos indeed encode the merger history of the galaxies. This means that from their halos, we can infer the masses of the largest satellites accreted by these galaxies.

    Laboratories for Quiet Accretion

    The authors then search for any indication of correlation between the stellar halo mass and the galaxy’s bulge mass or black hole mass. They find that their galaxy sample has a wide range in stellar halo masses that don’t correlate significantly with the bulge-to-total ratio, bulge mass, or black hole mass of the galaxy. This is true not only for the pseudobulges, but also for the classical bulges.

    4
    The galaxy Messier 81 has a massive classical bulge but an anemic stellar halo containing only 2% of its total stellar mass. This galaxy may be a useful laboratory for studying quiet accretion events. [Subaru Telescope (NAOJ)/HST/R. Colombari/R. Gendler]


    NAOJ/Subaru Telescope at Mauna Kea Hawaii, USA

    This outcome suggests that not even the classical bulges form primarily via minor and major merging activity. Instead, the bulges all form from a variety of mechanisms: a few are likely created by mergers, but the remainder are probably caused by quieter means like secular evolution, disk instabilities or misaligned gas accretion.

    These findings challenge the classical models of massive bulge formation and suggest that more detailed simulations and observations are necessary to unravel how the bulges and black holes at the centers of Milky-Way-like galaxies are grown. In particular, the galaxies with massive classical bulges but without massive stellar halos (the galaxy M81 is suggested as an example) may be ideal laboratories for studying quiet growth mechanisms.

    Citation

    Eric F. Bell et al 2017 ApJL 837 L8. doi:10.3847/2041-8213/aa6158

    See the full article here .

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  • richardmitnick 3:12 pm on March 23, 2017 Permalink | Reply
    Tags: , Astrophysics, , , , From NASA: "NASA Embraces Small Satellites" Video and text,   

    From NASA: “NASA Embraces Small Satellites” Video and text 

    NASA image
    NASA


    Access mp4 video here .

    The earliest satellites of the Space Age were small. Sputnik, for instance, weighed just 184.3 lbs. America’s first satellite, Explorer 1, was even smaller at only about 30 lbs.

    Over time, satellites grew to accommodate more sensors with greater capabilities, but thanks to miniaturization and new technology capabilities, small is back in vogue.

    NASA is one of many government agencies, universities, and commercial organizations embracing small satellite designs, from tiny CubeSats to micro-satellites. A basic CubeSat has 4 inch sides and weighs just a few pounds!

    A CubeSat can be put into place a number of different ways. It can be a hitchhiker, flying to space onboard a rocket whose main purpose is to launch a full-sized satellite. Or it can be put into orbit from the International Space Station. Astronauts recently used this technique when they deployed the Miniature X-Ray Solar Spectrometer (MinXSS), a CubeSat that studies solar flares.

    2
    On Feb. 2, 2016, NASA announced which CubeSats will fly on the inaugural flight of the agency’s Space Launch System in late 2018. CubeSats are small satellites, about the size of a cereal box, which provide an inexpensive way to access space. This file photo shows a set of NanoRacks CubeSats in space after their deployment in 2014.
    Credits: NASA

    In 2018, NASA plans to launch the CubeSat to study Solar Particles (CuSP). It will hitch a ride out of Earth orbit during an uncrewed test flight of NASA’s Space Launch System.

    CuSP could serve as a small “space weather buoy.”

    Eric Christian, CuSP’s lead scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland says, “Right now, with our current fleet of large satellites, it’s like we’re trying to understand weather for the entire Pacific Ocean with just a handful of weather stations. We need to collect data from more locations.”

    For certain areas of science, having a larger number of less expensive missions will provide a powerful opportunity to really understand a given environment. Christian says, “If you had, say, 20 CubeSats in different orbits, you could really start to understand the space environment in three dimensions.”

    NASA scientists are taking this approach of using a constellation of sensors to probe the details of a large area with a number of recently launched and upcoming missions.

    The Cyclone Global Navigation Satallite System, or CYGNSS, launched in December 2016. CYGNSS uses eight micro-satellites to measure ocean surface winds in and near the eyes of tropical cyclones, typhoons, and hurricanes to learn about their rapid intensification. These micro-satellites each weigh about 65 lbs, larger than a CubeSat but still very small compared to traditional satellite designs.

    Additionally, the first four selections from the In-Space Validation of Earth Science Technologies (InVEST) program recently began launching. The goal of the InVEST program is to validate new technologies in space prior to use in a science mission.

    RAVAN, the first of the InVEST CubeSats, was launched in November 2016 to demonstrate a new way to measure radiation reflected by Earth. The next three InVEST missions to launch, HARP, IceCube, and MiRaTA, will demonstrate technologies that may pave the way for future satellites to measure clouds and aerosols suspended in Earth’s atmosphere, probe the role of icy clouds in climate change, and collect atmospheric temperature, water vapor, and cloud ice data through remote sensing, respectively.

    NASA’s Science Mission Directorate is looking to develop scientific CubeSats that cut across all NASA Science through the SMD CubeSat Initiative Program.

    Andrea Martin, communications specialist for NASA’s Earth Science Technology Office, believes this is just the beginning. She says, “CubeSats could be flown in formation, known as constellations, with quick revisit times to better capture the dynamic processes of Earth. Multiple CubeSats can also take complementary measurements unachievable by a single larger mission.” She envisions big things ahead for these little satellites.

    For more news about CubeSats and other cutting edge technologies both big and small, stay tuned to science.nasa.gov.

    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 2:59 pm on March 23, 2017 Permalink | Reply
    Tags: ALMA Observes Galaxies Embedded in Super-Halos, , Astrophysics, , , ,   

    From ALMA: “ALMA Observes Galaxies Embedded in Super-Halos” 

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

    23 March 2017
    Nicolás Lira T.
    Press Coordinator
    Joint ALMA Observatory
    Santiago, Chile
    Tel: +56 2 24 67 65 19
    Cell: +56 9 94 45 77 26
    Email: nicolas.lira@alma.cl

    Charles E. Blue
    Public Information Officer
    National Radio Astronomy Observatory
    Charlottesville, Virginia, USA
    Tel: +1 434 296 0314
    Cell: +1 202 236 6324
    E-mail: cblue@nrao.edu

    Masaaki Hiramatsu

    Education and Public Outreach Officer, NAOJ Chile
    Observatory
Tokyo, Japan

    Tel: +81 422 34 3630

    E-mail: hiramatsu.masaaki@nao.ac.jp

    Richard Hook
    Public Information Officer, ESO

    Garching bei München, Germany

    Tel: +49 89 3200 6655

    Cell: +49 151 1537 3591
    Email: rhook@eso.org

    1
    Artist impression of a progenitor of Milky Way-like galaxy in the early Universe with a background quasar shining through a ‘super halo’ of hydrogen gas surrounding the galaxy. New ALMA observations of two such galaxies reveal that those large halos extend well beyond the galaxies’ dusty, star-forming disks. The galaxies were initially found by the absorption of background quasar light passing through the galaxies. ALMA was able to image the ionized carbon in the galaxies’ disks, revealing crucial details about their structures. Credit: A. Angelich (NRAO/AUI/NSF).

    By harnessing the extreme sensitivity of the Atacama Large Millimeter/submillimeter Array (ALMA), astronomers have directly observed a pair of Milky Way-like galaxies seen when the Universe was only eight percent of its current age. These progenitors of today’s giant spiral galaxies are surrounded by “super halos” of hydrogen gas that extend many tens of thousands of light-years beyond their dusty, star-filled disks.

    Astronomers initially detected these galaxies by studying the intense light from even-more-distant quasars. As this light travels through an intervening galaxy on its way to Earth, it can pick up the unique spectral signature from the galaxy’s gas. This technique, however, generally prevents astronomers from seeing the actual light emitted by the galaxy, which is overwhelmed by the much brighter emission from the background quasar.

    “Imagine a tiny firefly next to a high-power searchlight. That’s what astronomers are up against when it comes to observing these young versions of our home galaxy,” said Marcel Neeleman a postdoctoral fellow at the University of California, Santa Cruz, and lead author on a paper appearing in the journal Science. “We can now see the galaxies themselves, which gives us a fantastic opportunity to learn about the earliest history of our galaxy and others like it.”

    With ALMA, the astronomers were finally able to observe the natural millimeter-wavelength “glow” emitted by ionized carbon in the dense and dusty star-forming regions of the galaxies. This carbon signature, however, is considerably offset from the gas first detected by quasar absorption. This extreme separation indicates that the galaxies’ gas content extends well beyond their star-filled disks, suggesting that each galaxy is embedded in a massive halo of hydrogen gas.

    “We had expected we would see faint emission right on top of the quasar, and instead we saw bright galaxies at large separations from the quasar,” said J. Xavier Prochaska, professor of astronomy and astrophysics at UC Santa Cruz and co-author of the paper. The separation from the quasar to the observed galaxy is about 137,000 light-years for one galaxy and about 59,000 light-years for the other.

    According to the researchers, the neutral hydrogen gas revealed by its absorption of quasar light is most likely part of a large halo or perhaps an extended disk of gas around the galaxy. “It’s not where the star formation is, and to see so much gas that far from the star-forming region means there is a large amount of neutral hydrogen around the galaxy,” Neeleman said.

    2
    Composite ALMA and optical image of a young Milky Way-like galaxy 12 billion light-years away and a background quasar 12.5 billion light-years away. Light from the quasar passed through the galaxy’s gas on its way to Earth, revealing the presence of the galaxy to astronomers. New ALMA observations of the galaxy’s ionized carbon (green) and dust continuum (blue) emission show that the dusty, star-forming disk of the galaxy is vastly offset from the gas detected by quasar absorption at optical wavelengths (red). This indicates that a massive halo of gas surrounds the galaxy. The optical data are from the Keck I Telescope at the W.M. Keck Observatory. Credit: ALMA (ESO/NAOJ/NRAO), M. Neeleman & J. Xavier Prochaska; Keck Observatory.


    Keck Observatory, Mauna Kea, Hawaii, USA

    The new ALMA data show that these young galaxies are already rotating, which is one of the hallmarks of the massive spiral galaxies we see in the Universe today. The ALMA observations further reveal that both galaxies are forming stars at moderately high rates: more than 100 solar masses per year in one galaxy and about 25 solar masses per year in the other.

    “These galaxies appear to be massive, dusty, and rapidly star-forming systems, with large, extended layers of gas,” Prochaska said.

    “ALMA has solved a decades-old question on galaxy formation,” said Chris Carilli, an astronomer with the National Radio Astronomy Observatory in Socorro, N.M., and co-author on the paper. “We now know that at least some very early galaxies have halos that are much more extended than previously considered, which may represent the future material for galaxy growth.”

    The galaxies, which are officially designated ALMA J081740.86+135138.2 and ALMA J120110.26+211756.2, are each about 12 billion light-years from Earth. The background quasars are each roughly 12.5 billion light-years from Earth.

    This research is presented in a paper titled “[C II] 158-μm emission from the host galaxies of damped Lyman alpha systems,” by M. Neeleman et al., scheduled for publication in the journal Science on 24 March 2017. [Link is above.]

    See the full article here .

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    The Atacama Large Millimeter/submillimeter Array (ALMA), an international astronomy facility, is a partnership of Europe, North America and East Asia in cooperation with the Republic of Chile. ALMA is funded in Europe by the European Organization for Astronomical Research in the Southern Hemisphere (ESO), in North America by the U.S. National Science Foundation (NSF) in cooperation with the National Research Council of Canada (NRC) and the National Science Council of Taiwan (NSC) and in East Asia by the National Institutes of Natural Sciences (NINS) of Japan in cooperation with the Academia Sinica (AS) in Taiwan.

    ALMA construction and operations are led on behalf of Europe by ESO, on behalf of North America by the National Radio Astronomy Observatory (NRAO), which is managed by Associated Universities, Inc. (AUI) and on behalf of East Asia by the National Astronomical Observatory of Japan (NAOJ). The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA.

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  • richardmitnick 12:31 pm on March 23, 2017 Permalink | Reply
    Tags: , Astrophysics, , , Hubble detects supermassive black hole kicked out of galactic core, ,   

    From ESA/Hubble: “Hubble detects supermassive black hole kicked out of galactic core”and from NASA/HubbleSite “Gravitational Wave Kicks Monster Black Hole Out Of Galactic Core “ 

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    NASA/ESA Hubble Telescope

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    From ESA/Hubble

    “Hubble detects supermassive black hole kicked out of galactic core”

    23 March 2017
    Marco Chiaberge
    Space Telescope Science Institute
    Baltimore, USA
    Tel: +1 410 338 4980
    Email: chiab@stsci.edu

    Stefano Bianchi
    Roma Tre University
    Rome, Italy
    Tel: +39 657337241
    Email: bianchi@fis.uniroma3.it

    Mathias Jäger
    ESA/Hubble, Public Information Officer
    Garching bei München, Germany
    Cell: +49 17662397500
    Email: mjaeger@partner.eso.org

    1
    The galaxy 3C186, located about 8 billion years from Earth, is most likely the result of a merger of two galaxies. This is supported by arc-shaped tidal tails, usually produced by a gravitational tug between two colliding galaxies, identified by the scientists. The merger of the galaxies also led to a merger of the two supermassive black holes in their centres, and the resultant black hole was then kicked out of its parent galaxy by the gravitational waves created by the merger. The bright, star-like looking quasar can be seen in the centre of the image. Its former host galaxy is the faint, extended object behind it. Credit: NASA, ESA, and M. Chiaberge (STScI/ESA)

    2
    An international team of astronomers using the NASA/ESA Hubble Space Telescope have uncovered a supermassive black hole that has been propelled out of the centre of the distant galaxy 3C186. The black hole was most likely ejected by the power of gravitational waves. This is the first time that astronomers found a supermassive black hole at such a large distance from its host galaxy centre.

    Though several other suspected runaway black holes have been seen elsewhere, none has so far been confirmed. Now astronomers using the NASA/ESA Hubble Space Telescope have detected a supermassive black hole, with a mass of one billion times the Sun’s, being kicked out of its parent galaxy. “We estimate that it took the equivalent energy of 100 million supernovae exploding simultaneously to jettison the black hole,” describes Stefano Bianchi, co-author of the study, from the Roma Tre University, Italy.

    The images taken by Hubble provided the first clue that the galaxy, named 3C186, was unusual. The images of the galaxy, located 8 billion light-years away, revealed a bright quasar, the energetic signature of an active black hole, located far from the galactic core. “Black holes reside in the centres of galaxies, so it’s unusual to see a quasar not in the centre,” recalls team leader Marco Chiaberge, ESA-AURA researcher at the Space Telescope Science Institute, USA.

    The team calculated that the black hole has already travelled about 35 000 light-years from the centre, which is more than the distance between the Sun and the centre of the Milky Way. And it continues its flight at a speed of 7.5 million kilometres per hour [1]. At this speed the black hole could travel from Earth to the Moon in three minutes.

    Although other scenarios to explain the observations cannot be excluded, the most plausible source of the propulsive energy is that this supermassive black hole was given a kick by gravitational waves [2] unleashed by the merger of two massive black holes at the centre of its host galaxy. This theory is supported by arc-shaped tidal tails identified by the scientists, produced by a gravitational tug between two colliding galaxies.

    According to the theory presented by the scientists, 1-2 billion years ago two galaxies — each with central, massive black holes — merged. The black holes whirled around each other at the centre of the newly-formed elliptical galaxy, creating gravitational waves that were flung out like water from a lawn sprinkler [3]. As the two black holes did not have the same mass and rotation rate, they emitted gravitational waves more strongly along one direction. When the two black holes finally merged, the anisotropic emission of gravitational waves generated a kick that shot the resulting black hole out of the galactic centre.

    “If our theory is correct, the observations provide strong evidence that supermassive black holes can actually merge,” explains Stefano Bianchi on the importance of the discovery. “There is already evidence of black hole collisions for stellar-mass black holes, but the process regulating supermassive black holes is more complex and not yet completely understood.”

    The researchers are lucky to have caught this unique event because not every black hole merger produces imbalanced gravitational waves that propel a black hole out of the galaxy. The team now wants to secure further observation time with Hubble, in combination with the Atacama Large Millimeter/submillimeter Array (ALMA) and other facilities, to more accurately measure the speed of the black hole and its surrounding gas disc, which may yield further insights into the nature of this rare object.
    Notes

    [1] As the black hole cannot be observed directly, the mass and the speed of the supermassive black holes were determined via spectroscopic analysis of its surrounding gas.

    [2] First predicted by Albert Einstein, gravitational waves are ripples in space that are created by accelerating massive objects. The ripples are similar to the concentric circles produced when a rock is thrown into a pond. In 2016, the Laser Interferometer Gravitational-wave Observatory (LIGO) helped astronomers prove that gravitational waves exist by detecting them emanating from the union of two stellar-mass black holes, which are several times more massive than the Sun.

    [3] The black holes get closer over time as they radiate away gravitational energy.

    The international team of astronomers in this study consists of Marco Chiaberge (STScI, USA; Johns Hopkins University, USA), Justin C. Ely (STScI, USA), Eileen Meyer (University of Maryland Baltimore County, USA), Markos Georganopoulos (University of Maryland Baltimore County, USA; NASA Goddard Space Flight Center, USA), Andrea Marinucci (Università degli Studi Roma Tre, Italy), Stefano Bianchi (Università degli Studi Roma Tre, Italy), Grant R. Tremblay (Yale University, USA), Brian Hilbert (STScI, USA), John Paul Kotyla (STScI, USA), Alessandro Capetti (INAF – Osservatorio Astrofisico di Torino, Italy), Stefi Baum (University of Manitoba, Canada), F. Duccio Macchetto (STScI, USA), George Miley (University of Leiden, Netherlands), Christopher O’Dea (University of Manitoba, Canada), Eric S. Perlman (Florida Institute of Technology, USA), William B. Sparks (STScI, USA) and Colin Norman (STScI, USA; Johns Hopkins University, USA)

    Image credit: NASA, ESA, M. Chiaberge (STScI/ESA)

    Science paper:
    The puzzling case of the radio-loud QSO 3C 186: a gravitational wave recoiling black hole in a young radio source?

    From NASA HubbleSite

    “Gravitational Wave Kicks Monster Black Hole Out Of Galactic Core “

    Mar 23, 2017

    Donna Weaver
    Space Telescope Science Institute, Baltimore, Maryland
    410-338-4493
    dweaver@stsci.edu

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

    Marco Chiaberge
    Space Telescope Science Institute and
    The Johns Hopkins University, Baltimore, Maryland
    410-338-4980
    marcoc@stsci.edu

    3
    Runaway black hole is the most massive ever detected far from its central home
    Normally, hefty black holes anchor the centers of galaxies. So researchers were surprised to discover a supermassive black hole speeding through the galactic suburbs. Black holes cannot be observed directly, but they are the energy source at the heart of quasars — intense, compact gushers of radiation that can outshine an entire galaxy. NASA’s Hubble Space Telescope made the discovery by finding a bright quasar located far from the center of the host galaxy.

    Researchers estimate that it took the equivalent energy of 100 million supernovas exploding simultaneously to jettison the black hole. What could pry this giant monster from its central home? The most plausible explanation for this propulsive energy is that the monster object was given a kick by gravitational waves unleashed by the merger of two black holes as a result of a collision between two galaxies. First predicted by Albert Einstein, gravitational waves are ripples in the fabric of space that are created when two massive objects collide.

    The Full [HubbleSite] Story

    Astronomers have uncovered a supermassive black hole that has been propelled out of the center of a distant galaxy by what could be the awesome power of gravitational waves.

    Though there have been several other suspected, similarly booted black holes elsewhere, none has been confirmed so far. Astronomers think this object, detected by NASA’s Hubble Space Telescope, is a very strong case. Weighing more than 1 billion suns, the rogue black hole is the most massive black hole ever detected to have been kicked out of its central home.

    Researchers estimate that it took the equivalent energy of 100 million supernovas exploding simultaneously to jettison the black hole. The most plausible explanation for this propulsive energy is that the monster object was given a kick by gravitational waves unleashed by the merger of two hefty black holes at the center of the host galaxy.

    First predicted by Albert Einstein, gravitational waves are ripples in space that are created when two massive objects collide. The ripples are similar to the concentric circles produced when a hefty rock is thrown into a pond. Last year, the Laser Interferometer Gravitational-Wave Observatory (LIGO) helped astronomers prove that gravitational waves exist by detecting them emanating from the union of two stellar-mass black holes, which are several times more massive than the sun.

    Hubble’s observations of the wayward black hole surprised the research team. “When I first saw this, I thought we were seeing something very peculiar,” said team leader Marco Chiaberge of the Space Telescope Science Institute (STScI) and Johns Hopkins University, in Baltimore, Maryland. “When we combined observations from Hubble, the Chandra X-ray Observatory, and the Sloan Digital Sky Survey, it all pointed towards the same scenario. The amount of data we collected, from X-rays to ultraviolet to near-infrared light, is definitely larger than for any of the other candidate rogue black holes.”

    Chiaberge’s paper will appear in the March 30 issue of Astronomy & Astrophysics.

    Hubble images taken in visible and near-infrared light provided the first clue that the galaxy was unusual. The images revealed a bright quasar, the energetic signature of a black hole, residing far from the galactic core. Black holes cannot be observed directly, but they are the energy source at the heart of quasars – intense, compact gushers of radiation that can outshine an entire galaxy. The quasar, named 3C 186, and its host galaxy reside 8 billion light-years away in a galaxy cluster. The team discovered the galaxy’s peculiar features while conducting a Hubble survey of distant galaxies unleashing powerful blasts of radiation in the throes of galaxy mergers.

    “I was anticipating seeing a lot of merging galaxies, and I was expecting to see messy host galaxies around the quasars, but I wasn’t really expecting to see a quasar that was clearly offset from the core of a regularly shaped galaxy,” Chiaberge recalled. “Black holes reside in the center of galaxies, so it’s unusual to see a quasar not in the center.”

    The team calculated the black hole’s distance from the core by comparing the distribution of starlight in the host galaxy with that of a normal elliptical galaxy from a computer model. The black hole had traveled more than 35,000 light-years from the center, which is more than the distance between the sun and the center of the Milky Way.

    Based on spectroscopic observations taken by Hubble and the Sloan survey, the researchers estimated the black hole’s mass and measured the speed of gas trapped near the behemoth object. Spectroscopy divides light into its component colors, which can be used to measure velocities in space. “To our surprise, we discovered that the gas around the black hole was flying away from the galaxy’s center at 4.7 million miles an hour,” said team member Justin Ely of STScI. This measurement is also a gauge of the black hole’s velocity, because the gas is gravitationally locked to the monster object.

    The astronomers calculated that the black hole is moving so fast it would travel from Earth to the moon in three minutes. That’s fast enough for the black hole to escape the galaxy in 20 million years and roam through the universe forever.

    The Hubble image revealed an interesting clue that helped explain the black hole’s wayward location. The host galaxy has faint arc-shaped features called tidal tails, produced by a gravitational tug between two colliding galaxies. This evidence suggests a possible union between the 3C 186 system and another galaxy, each with central, massive black holes that may have eventually merged.

    Based on this visible evidence, along with theoretical work, the researchers developed a scenario to describe how the behemoth black hole could be expelled from its central home. According to their theory, two galaxies merge, and their black holes settle into the center of the newly formed elliptical galaxy. As the black holes whirl around each other, gravity waves are flung out like water from a lawn sprinkler. The hefty objects move closer to each other over time as they radiate away gravitational energy. If the two black holes do not have the same mass and rotation rate, they emit gravitational waves more strongly along one direction. When the two black holes collide, they stop producing gravitational waves. The newly merged black hole then recoils in the opposite direction of the strongest gravitational waves and shoots off like a rocket.

    The researchers are lucky to have caught this unique event because not every black-hole merger produces imbalanced gravitational waves that propel a black hole in the opposite direction. “This asymmetry depends on properties such as the mass and the relative orientation of the back holes’ rotation axes before the merger,” said team member Colin Norman of STScI and Johns Hopkins University. “That’s why these objects are so rare.”

    An alternative explanation for the offset quasar, although unlikely, proposes that the bright object does not reside within the galaxy. Instead, the quasar is located behind the galaxy, but the Hubble image gives the illusion that it is at the same distance as the galaxy. If this were the case, the researchers should have detected a galaxy in the background hosting the quasar.

    If the researchers’ interpretation is correct, the observations may provide strong evidence that supermassive black holes can actually merge. Astronomers have evidence of black-hole collisions for stellar-mass black holes, but the process regulating supermassive black holes is more complex and not completely understood.

    The team hopes to use Hubble again, in combination with the Atacama Large Millimeter/submillimeter Array (ALMA) and other facilities, to more accurately measure the speed of the black hole and its gas disk, which may yield more insight into the nature of this bizarre object.

    See the full ESA article here .

    See the full NASA HubbleSite story 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 12:16 pm on March 23, 2017 Permalink | Reply
    Tags: , Andromeda's Bright X-Ray Mystery Solved by NuSTAR, , Astrophysics, , , , Swift J0042.6+4112   

    From JPL-Caltech: “Andromeda’s Bright X-Ray Mystery Solved by NuSTAR” 

    NASA JPL Banner

    JPL-Caltech

    March 23, 2017
    Elizabeth Landau
    Jet Propulsion Laboratory, Pasadena, Calif.
    818-354-6425
    elizabeth.landau@jpl.nasa.gov

    1
    NASA’s Nuclear Spectroscope Telescope Array, or NuSTAR, has identified a candidate pulsar in Andromeda — the nearest large galaxy to the Milky Way. This likely pulsar is brighter at high energies than the Andromeda galaxy’s entire black hole population. Image credit: NASA/JPL-Caltech/GSFC/JHU


    NASA/NuSTAR

    The Milky Way’s closest neighbor, Andromeda, features a dominant source of high-energy X-ray emission, but its identity was mysterious until now. As reported in a new study, NASA’s NuSTAR (Nuclear Spectroscopic Telescope Array) mission has pinpointed an object responsible for this high-energy radiation.

    The object, called Swift J0042.6+4112, is a possible pulsar, the dense remnant of a dead star that is highly magnetized and spinning, researchers say. This interpretation is based on its emission in high-energy X-rays, which NuSTAR is uniquely capable of measuring. The object’s spectrum is very similar to known pulsars in the Milky Way.

    It is likely in a binary system, in which material from a stellar companion gets pulled onto the pulsar, spewing high-energy radiation as the material heats up.

    “We didn’t know what it was until we looked at it with NuSTAR,” said Mihoko Yukita, lead author of a study about the object, based at Johns Hopkins University in Baltimore. The study is published in The Astrophysical Journal.

    This candidate pulsar is shown as a blue dot in a NuSTAR X-ray image of Andromeda (also called M31), where the color blue is chosen to represent the highest-energy X-rays. It appears brighter in high-energy X-rays than anything else in the galaxy.

    The study brings together many different observations of the object from various spacecraft. In 2013, NASA’s Swift satellite reported it as a high-energy source, but its classification was unknown, as there are many objects emitting low energy X-rays in the region. The lower-energy X-ray emission from the object turns out to be a source first identified in the 1970s by NASA’s Einstein Observatory. Other spacecraft, such as NASA’s Chandra X-ray Observatory and ESA’s XMM-Newton had also detected it. However, it wasn’t until the new study by NuSTAR, aided by supporting Swift satellite data, that researchers realized it was the same object as this likely pulsar that dominates the high energy X-ray light of Andromeda.

    Traditionally, astronomers have thought that actively feeding black holes, which are more massive than pulsars, usually dominate the high-energy X-ray light in galaxies. As gas spirals closer and closer to the black hole in a structure called an accretion disk, this material gets heated to extremely high temperatures and gives off high-energy radiation. This pulsar, which has a lower mass than any of Andromeda’s black holes, is brighter at high energies than the galaxy’s entire black hole population.

    Even the supermassive black hole in the center of Andromeda does not have significant high-energy X-ray emission associated with it. It is unexpected that a single pulsar would instead be dominating the galaxy in high-energy X-ray light.

    “NuSTAR has made us realize the general importance of pulsar systems as X-ray-emitting components of galaxies, and the possibility that the high energy X-ray light of Andromeda is dominated by a single pulsar system only adds to this emerging picture,” said Ann Hornschemeier, co-author of the study and based at NASA’s Goddard Space Flight Center, Greenbelt, Maryland.

    Andromeda is a spiral galaxy slightly larger than the Milky Way. It resides 2.5 million light-years from our own galaxy, which is considered very close, given the broader scale of the universe. Stargazers can see Andromeda without a telescope on dark, clear nights.

    “Since we can’t get outside our galaxy and study it in an unbiased way, Andromeda is the closest thing we have to looking in a mirror,” Hornschemeier said.

    NuSTAR is a Small Explorer mission led by Caltech and managed by JPL for NASA’s Science Mission Directorate in Washington. NuSTAR was developed in partnership with the Danish Technical University and the Italian Space Agency (ASI). The spacecraft was built by Orbital Sciences Corp., Dulles, Virginia. NuSTAR’s mission operations center is at UC Berkeley, and the official data archive is at NASA’s High Energy Astrophysics Science Archive Research Center. ASI provides the mission’s ground station and a mirror archive. JPL is managed by Caltech for NASA.

    For more information on NuSTAR, visit:

    http://www.nasa.gov/nustar

    http://www.nustar.caltech.edu

    See the full article here .

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    Jet Propulsion Laboratory (JPL) is a federally funded research and development center and NASA field center located in the San Gabriel Valley area of Los Angeles County, California, United States. Although the facility has a Pasadena postal address, it is actually headquartered in the city of La Cañada Flintridge [1], on the northwest border of Pasadena. JPL is managed by the nearby California Institute of Technology (Caltech) for the National Aeronautics and Space Administration. The Laboratory’s primary function is the construction and operation of robotic planetary spacecraft, though it also conducts Earth-orbit and astronomy missions. It is also responsible for operating NASA’s Deep Space Network.

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  • richardmitnick 10:57 am on March 23, 2017 Permalink | Reply
    Tags: , Astrophysics, , , Tracing Aromatic Molecules in the Early Universe, , University of California-based MOSDEF survey   

    From UC Riverside: “Tracing Aromatic Molecules in the Early Universe” 

    UC Riverside bloc

    UC Riverside

    March 22, 2017
    Sean Nealon
    A molecule found in car engine exhaust fumes that is thought to have contributed to the origin of life on Earth has made astronomers heavily underestimate the amount of stars that were forming in the early Universe, a University of California, Riverside-led study has found.

    1
    In this study, astronomers used data from the Keck and Spitzer telescopes to trace the star forming and dusty regions of galaxies at about 10 billion years ago. The picture in the background shows the GOODS field, one of the five regions in the sky that was observed for this study. Credit: Mario De Leo-Winkler with images from the Spitzer Space Telescope, NASA, ESA and the Hubble Heritage team.

    That molecule is called polycyclic aromatic hydrocarbon (PAH). On Earth it is also found in coal and tar. In space, it is a component of dust, which along with gas, fills the space between stars within galaxies.

    The study, which was just published in the Astrophysical Journal, represents the first time that astronomers have been able to measure variations of PAH emissions in distant galaxies with different properties. It has important implications for the studies of distant galaxies because absorption and emission of energy by dust particles can change astronomers’ views of distant galaxies.

    “Despite the ubiquity of PAHs in space, observing them in distant galaxies has been a challenging task,” said Irene Shivaei, a graduate student at UC Riverside, and leader of the study. “A significant part of our knowledge of the properties and amounts of PAHs in other galaxies is limited to the nearby universe.”

    The research was conducted as part of the University of California-based MOSDEF survey, a study that uses the Keck telescope in Hawaii to observe the content of about 1,500 galaxies when the universe was 1.5 to 4.5 billion years old. The researchers observed the emitted visible-light spectra of a large and representative sample of galaxies during the peak-era of star formation activity in the universe.

    In addition, the researchers incorporated infrared imaging data from the NASA Spitzer Space Telescope and the European Space Agency-operated Herschel Space Observatory to trace the polycyclic aromatic hydrocarbon emission in mid-infrared bands and the thermal dust emission in far-infrared wavelengths.

    The researchers concluded that the emission of polycyclic aromatic hydrocarbon molecules is suppressed in low-mass galaxies, which also have a lower fraction of metals, which are atoms heavier than hydrogen and helium. These results indicate that the polycyclic aromatic hydrocarbon molecules are likely to be destroyed in the hostile environment of low-mass and metal-poor galaxies with intense radiation.

    The researchers also found that the polycyclic aromatic hydrocarbon emission is relatively weaker in young galaxies compared to older ones, which may be due to the fact that polycyclic aromatic hydrocarbon molecules are not produced in large quantities in young galaxies.

    They found that the star-formation activity and infrared luminosity in the universe 10 billion years ago is approximately 30 percent higher than previously measured.

    Studying the properties of the polycyclic aromatic hydrocarbon mid-infrared emission bands in distant universe is of fundamental importance to improving our understanding of the evolution of dust and chemical enrichment in galaxies throughout cosmic time. The planned launch of the James Webb Space Telescope in 2018 will push the boundaries of our knowledge on dust and polycyclic aromatic hydrocarbon in the early universe.

    In addition to Shivaei, the authors are: Naveen Reddy, Brian Siana, and Bahram Mobasher, of UC Riverside; Alice Shapley and Ryan L. Sanders, of UCLA; Mariska Kriek, Sedona H. Price, and Tom Zick, of UC Berkeley; and Alison L. Coil and Mojegan Azadi, of UC San Diego.

    Mario De Leo-Winkler, a postdoctoral researcher in the UCR Department of Physics and Astronomy, made significant contributions to this article.

    See the full article here .

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    UC Riverside Campus

    The University of California, Riverside is one of 10 universities within the prestigious University of California system, and the only UC located in Inland Southern California.

    Widely recognized as one of the most ethnically diverse research universities in the nation, UCR’s current enrollment is more than 21,000 students, with a goal of 25,000 students by 2020. The campus is in the midst of a tremendous growth spurt with new and remodeled facilities coming on-line on a regular basis.

    We are located approximately 50 miles east of downtown Los Angeles. UCR is also within easy driving distance of dozens of major cultural and recreational sites, as well as desert, mountain and coastal destinations.

     
  • richardmitnick 7:49 am on March 23, 2017 Permalink | Reply
    Tags: , Astrophysics, , , , , , Swarm detects asymmetry   

    From ESA: “Swarm detects asymmetry” 

    ESA Space For Europe Banner

    European Space Agency

    22 March 2017

    1
    Title Swarm
    Released 23/03/2012 1:18 pm
    Copyright ESA/AOES Medialab
    Swarm is ESA’s first constellation of Earth observation satellites designed to measure the magnetic signals from Earth’s core, mantle, crust, oceans, ionosphere and magnetosphere, providing data that will allow scientists to study the complexities of our protective magnetic field.

    Strong electric currents in the upper atmosphere are known to vary according to the season, but ESA’s Swarm mission has discovered that this seasonal variation is not the same in the north and south polar regions.

    Named after Kristian Birkeland, the scientist a century ago who first postulated that the ‘northern lights’ were linked to electrically charged particles in the solar wind, these currents flow along Earth’s magnetic field lines in the polar regions.

    Magnetic field measurements from ESA’s Swarm satellite constellation are allowing scientists to understand more about these powerful currents, which carry up to 1 TW of electric power to the upper atmosphere. This is about 30 times the energy consumed in New York during a heatwave.

    2
    Title Seasonal asymmetry
    Released 22/03/2017 10:24 am
    Copyright DTU/BCSS
    Three years of measurements from ESA’s Swarm mission have be combined with measurements from Germany’s earlier Champ satellite to produce global climatological maps of Birkeland currents. These currents tend to be weak for a northwards interplanetary field and strong for a southwards field. Importantly, these new results also reveal that the strength of the currents is not the same in both hemispheres. These hemispheric differences may relate to asymmetry in Earth’s main magnetic field.

    It is important to understand the interplay between these Birkeland currents and the solar wind that bombards our planet and that can potentially cause power and communication blackouts.

    New findings, presented this week at the Swarm science meeting in Canada, show how three years of measurements from the mission were combined with measurements from Germany’s earlier Champ satellite to produce global climatological maps of these currents.

    3
    Title Earth’s protective shield
    Released 06/02/2014 2:09 pm
    Copyright ESA/ATG medialab
    The magnetic field and electric currents in and around Earth generate complex forces that have immeasurable impact on every day life. The field can be thought of as a huge bubble, protecting us from cosmic radiation and charged particles that bombard Earth in solar winds.

    Moreover, these results show differences between currents in the northern and southern hemisphere, how they change with the season and how they vary according to the strength of the solar wind.

    Karl Laundal, from the Birkeland Centre for Space Science, explained, “Interaction between Earth’s magnetic field and the interplanetary magnetic field – meaning part of the Sun’s magnetic field carried by solar wind – depends on how the interplanetary field is orientated.

    “While this sounds complicated, it means that hardly any solar wind can enter the magnetosphere and arrive at Earth if the interplanetary magnetic field points north, parallel to Earth’s magnetic field.

    “On the other hand, if the interplanetary field points south, the opposite is true and this allows a connection to be made with Earth’s magnetic field.

    “Part of the energy in solar wind then further energises the charged particles that are responsible for the visible light displays of the auroras.”

    Birkeland currents therefore tend to be weak for a northwards interplanetary field and strong for a southwards field.

    Importantly, these new results also reveal that the strength of the currents is not the same in both hemispheres. These hemispheric differences may relate to asymmetry in Earth’s main magnetic field.

    In fact, the two geomagnetic poles are not geometrically opposite to one another, and the magnetic field intensity is also not the same in the north as in the south.

    Dr Laundal said, “The main reason for this probably has to do with differences in Earth’s main field. Such differences imply that the ionosphere–magnetosphere coupling is different in the two hemispheres.

    “In particular, the magnetic pole is more offset with respect to the geographic pole in the south compared to north, which leads to different variations in sunlight in the ‘magnetic hemispheres’. Because of these differences, the two hemispheres do not respond symmetrically to solar wind driving or changing seasons.

    “Swarm is a fantastic tool for space science studies. The high-quality measurements and the fact that there are three satellites working in concert hold many new clues about how our home planet interacts with the space around it. It’s a fascinating time.”

    4

    See the full article here .

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    The European Space Agency (ESA), established in 1975, is an intergovernmental organization dedicated to the exploration of space, currently with 19 member states. Headquartered in Paris, ESA has a staff of more than 2,000. ESA’s space flight program includes human spaceflight, mainly through the participation in the International Space Station program, the launch and operations of unmanned exploration missions to other planets and the Moon, Earth observation, science, telecommunication as well as maintaining a major spaceport, the Guiana Space Centre at Kourou, French Guiana, and designing launch vehicles. ESA science missions are based at ESTEC in Noordwijk, Netherlands, Earth Observation missions at ESRIN in Frascati, Italy, ESA Mission Control (ESOC) is in Darmstadt, Germany, the European Astronaut Centre (EAC) that trains astronauts for future missions is situated in Cologne, Germany, and the European Space Astronomy Centre is located in Villanueva de la Cañada, Spain.

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  • richardmitnick 5:21 pm on March 22, 2017 Permalink | Reply
    Tags: , , , Astrophysics, , , , Dark Energy Spectroscopic Instrument (DESI), , , New Study Maps Space Dust in 3-D, Pan-STARRS,   

    From LBNL: “New Study Maps Space Dust in 3-D” 

    Berkeley Logo

    Berkeley Lab

    March 22, 2017
    Glenn Roberts Jr
    geroberts@lbl.gov
    510-486-5582


    Access mp4 video here .
    This animation shows a 3-D rendering of space dust, as viewed in a several-kiloparsec (thousands of light years) loop through and out of the Milky Way’s galactic plane. The animation uses data for hundreds of millions of stars from Pan-STARRS1 and 2MASS surveys, and is made available through a Creative Commons License. (Credit: Gregory M. Green/SLAC, KIPAC)

    Consider that the Earth is just a giant cosmic dust bunny—a big bundle of debris amassed from exploded stars. We Earthlings are essentially just little clumps of stardust, too, albeit with very complex chemistry.

    And because outer space is a very dusty place, that makes things very difficult for astronomers and astrophysicists who are trying to peer farther across the universe or deep into the center of our own galaxy to learn more about their structure, formation and evolution.

    Building a better dust map

    Now, a new study led by Edward F. Schlafly, a Hubble Fellow in the Physics Division at the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab), is providing a detailed, 3-D look at dust on a scale spanning thousands of light-years in our Milky Way galaxy. The study was published today in The Astrophysical Journal.

    This dust map is of critical importance for the Dark Energy Spectroscopic Instrument (DESI), a Berkeley Lab-led project that will measure the universe’s accelerating expansion rate when it starts up in 2019. DESI will build a map of more than 30 million distant galaxies, but that map will be distorted if this dust is ignored.

    “The light from those distant galaxies travels for billions of years before we see it,” according to Schlafly, “but in the last thousand years of its journey toward us a few percent of that light is absorbed and scattered by dust in our own galaxy. We need to correct for that.”

    Just as airborne dust in Earth’s sky contributes to the atmospheric haze that gives us brilliant oranges and reds in sunrises and sunsets, dust can also make distant galaxies and other space objects appear redder in the sky, distorting their distance and in some cases concealing them from view.

    Scientists are constantly developing better ways to map out this interstellar dust and understand its concentration, composition, and common particle sizes and shapes.

    1
    The dark regions show very dense dust clouds. The red stars tend to be reddened by dust, while the blue stars are in front of the dust clouds. These images are part of a survey of the southern galactic plane. (Credit: Legacy Survey/NOAO, AURA, NSF)

    Once we can solve the dust problem by creating better dust maps and learning new details about the properties of this space dust, this can give us a much more precise gauge of distances to faraway stars in the Milky Way, like a galactic GPS. Dust maps can also help to better gauge the distance to supernovae events by taking into account the effects of dust in reddening their light.

    “The overarching aim of this project is to map dust in three dimensions—to find out how much dust is in any 3-D region in the sky and in the Milky Way galaxy,” Schlafly said.

    Combined data from sky surveys shed new light on dust

    Taking data from separate sky surveys conducted with telescopes on Maui and in New Mexico, Schlafly’s research team composed maps that compare dust within one kiloparsec, or 3,262 light-years, in the outer Milky Way—including collections of gas and dust known as molecular clouds that can contain dense star- and planet-forming regions known as nebulae—with more distant dust in the galaxy.

    2
    Pan-STARRS2 and PanSTARS1 telescopes atop Haleakalā on the island of Maui, Hawaii. (Credit: Pan-STARRS)

    The resolution of these 3-D dust maps is many times better than anything that previously existed,” said Schlafly.

    This undertaking was made possible by the combination of a very detailed multiyear survey known as Pan-STARRS that is powered by a 1.4-gigapixel digital camera and covers three-fourths of the visible sky, and a separate survey called APOGEE that used a technique known as infrared spectroscopy.

    3
    A compressed view of the entire sky visible from Hawaii by the Pan-STARRS1 Observatory. The image is a compilation of half a million exposures, each about 45 seconds in length, taken over a period of four years. The disk of the Milky Way looks like a yellow arc, and the dust lanes show up as reddish-brown filaments. The background is made up of billions of faint stars and galaxies. (Credit: D. Farrow/Pan-STARRS1 Science Consortium, and Max Planck Institute for Extraterrestrial Physics)

    Infrared measurements can effectively cut through the dust that obscures many other types of observations and provides a more precise measurement of stars’ natural color. The APOGEE experiment focused on the light from about 100,000 red giant stars across the Milky Way, including those in its central halo.


    SDSS Telescope at Apache Point Observatory, NM, USA

    What they found is a more complex picture of dust than earlier research and models had suggested. The dust properties within 1 kiloparsec of the sun, which scientists measure with a light-obscuring property known as its “extinction curve,” is different than that of the dust properties in the more remote galactic plane and outer galaxy.

    New questions emerge on the makeup of space dust

    The results, researchers found, appear to be in conflict with models that expect dust to be more predictably distributed, and to simply exhibit larger grain sizes in areas where more dust resides. But the observations find that the dust properties vary little with the amount of dust, so the models may need to be adjusted to account for a different chemical makeup, for example.

    “In denser regions, it was thought that dust grains will conglomerate, so you have more big grains and fewer small grains,” Schlafly said. But the observations show that dense dust clouds look much the same as less concentrated dust clouds, so that variations in dust properties are not just a product of dust density: “whatever is driving this is not just conglomeration in these regions.”

    He added, “The message to me that we don’t yet know what’s going on. I don’t think the existing (models) are correct, or they are only right at the very highest densities.”

    Accurate measures of the chemical makeup of space dust are important, Schlafly said. “A large amount of chemistry takes place on dust grains, and you can only form molecular hydrogen on the surface of dust grains,” he said—this molecular hydrogen is essential in the formation of stars and planets.


    Access mp4 video here .
    This animation shows a 3-D rendering of dust, as viewed from a 50-parsec (163-light-year) loop around the sun. The animation uses data for hundreds of millions of stars from Pan-STARRS1 and 2MASS surveys, and is made available through a Creative Commons License: https://creativecommons.org/licenses/by-sa/4.0/. (Credit: Gregory M. Green/SLAC, KIPAC)

    Even with a growing collection of dust data, we still have an incomplete dust map of our galaxy. “There is about one-third of the galaxy that’s missing,” Schlafly said, “and we’re working right now on imaging this ‘missing third’ of the galaxy.” A sky survey that will complete the imaging of the southern galactic plane and provide this missing data should wrap up in May, he said.

    APOGEE-2, a follow-up survey to APOGEE, for example, will provide more complete maps of the dust in the local galaxy, and other instruments are expected to provide better dust maps for nearby galaxies, too.

    While the density of dust shrouds our view of the center of the Milky Way, Schlafly said there will be progress, too, in seeing deeper and collecting better dust measurements there as well.

    Researchers at the Harvard-Smithsonian Center for Astrophysics and Harvard University also participated in this work.

    4
    The planned APOGEE-2 survey area overlain on an image of the Milky Way. Each dot shows a position where APOGEE-2 will obtain stellar spectra. (Credit: APOGEE-2)

    APOGEE is a part of the Sloan Digital Sky Survey III (SDSS-III), with participating institutions including Berkeley Lab, the Alfred P. Sloan Foundation, and the National Science Foundation. PanSTARRS1 surveys are supported by the University of Hawaii Institute for Astronomy; the Pan-STARRS Project Office; the Max-Planck Society and its participating institutes in Germany; the Johns Hopkins University; the University of Durham, the University of Edinburgh, and the Queen’s University Belfast in the U.K.; the Harvard-Smithsonian Center for Astrophysics; the Las Cumbres Observatory Global Telescope Network Inc.; and the National Central University of Taiwan. Pan-STARRS is supported by the U.S. Air Force.

    See the full article here .

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