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  • richardmitnick 10:06 am on December 14, 2015 Permalink | Reply
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    From AAS NOVA: “Featured Image: Reddened Stars Reveal Andromeda’s Dust” 

    AASNOVA

    Amercan Astronomical Society

    14 December 2015
    Susanna Kohler

    1

    As distant light travels on a path toward us, it can be absorbed by intervening, interstellar dust. Much work has been done to understand this “dust extinction” in the Milky Way, providing us with detailed information about the properties of the dust in our galaxy. Far less, however, is known about the dust extinction of other galaxies. The image above, taken with the ultraviolet space telescope GALEX, identifies the locations of four stars in the nearby Andromeda galaxy that are reddened due to extinction of their light by dust within Andromeda.

    NASA Galex telescope
    NASA/GALEX

    In a recent study led by Geoffrey Clayton (Louisiana State University), new, high-signal-to-noise spectra were obtained for these four stars using Hubble’s Space Telescope [HST] Imaging Spectrograph. These observations have allowed the authors to construct dust extinction curves to carefully study the nature of Andromeda’s interstellar dust. To learn about the results, see the paper below.

    NASA Hubble Telescope
    HST

    NASA Hubble Space Telescope Imaging Spectrograph
    NASA Hubble Space Telescope Imaging Spectrograph

    Citation

    Geoffrey C. Clayton et al 2015 ApJ 815 14. doi:10.1088/0004-637X/815/1/14

    See the full article here .

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  • richardmitnick 4:14 pm on September 16, 2015 Permalink | Reply
    Tags: , , , , NASA Galex,   

    From JPL: “Funky Light Signal From Colliding Black Holes Explained” 

    JPL

    September 16, 2015
    Whitney Clavin
    Jet Propulsion Laboratory, Pasadena, California
    818-354-4673
    whitney.clavin@jpl.nasa.gov

    1
    This simulation helps explain an odd light signal thought to be coming from a close-knit pair of merging black holes, PG 1302-102, located 3.5 billion light-years away. Image credit: Columbia University

    Entangled by gravity and destined to merge, two candidate black holes in a distant galaxy appear to be locked in an intricate dance. Researchers using data from NASA’s Galaxy Evolution Explorer (GALEX) and NASA’s Hubble Space Telescope have come up with the most compelling confirmation yet for the existence of these merging black holes and have found new details about their odd, cyclical light signal.

    NASA Galex telescope
    GALEX

    NASA Hubble Telescope
    NASA/ESA Hubble

    The candidate black hole duo, called PG 1302-102, was first identified earlier this year using ground-based telescopes.

    Mt Lemon 24 inch telescope
    Mt Lemon telescope

    Caltech Catalina Real Time Survey Telescope
    Caltech Catalina Real Time Survey Telescope

    The black holes are the tightest orbiting pair detected so far, with a separation not much bigger than the diameter of our solar system. They are expected to collide and merge in less than a million years, triggering a titanic blast with the power of 100 million supernovae.

    Researchers are studying this pair to better understand how galaxies and the monstrous black holes at their cores merge — a common occurrence in the early universe. But as common as these events were, they are hard to spot and confirm.

    PG 1302-102 is one of only a handful of good binary black hole candidates. It was discovered and reported earlier this year by researchers at the California Institute of Technology3 in Pasadena, after they scrutinized an unusual light signal coming from the center of a galaxy. The researchers, who used telescopes in the Catalina Real-Time Transient Survey, demonstrated that the varying signal is likely generated by the motion of two black holes, which swing around each other every five years. While the black holes themselves don’t give off light, the material surrounding them does.

    In the new study, published in the Sept. 17 issue of Nature, researchers found more evidence to support and confirm the close-knit dance of these black holes. Using ultraviolet data from GALEX and Hubble, they were able to track the system’s changing light patterns over the past 20 years.

    “We were lucky to have GALEX data to look through,” said co-author David Schiminovich of Columbia University in New York. “We went back into the GALEX archives and found that the object just happened to have been observed six times.”

    Hubble, which sees ultraviolet light in addition to visible and other wavelengths of light, had likewise observed the object in the past.

    The ultraviolet light was important to test a prediction of how the black holes generate a cyclical light pattern. The idea is that one of the black holes in the pair is giving off more light — it is gobbling up more matter than the other one, and this process heats up matter that emits energetic light. As this black hole orbits around its partner every five years, its light changes and appears to brighten as it heads toward us.

    “It’s as if a 60-Watt light bulb suddenly appears to be 100 Watts,” explained Daniel D’Orazio, lead author of the study from Columbia University. “As the black hole light speeds away from us, it appears as a dimmer 20-Watt bulb.”

    What’s causing the changes in light? One set of changes has to do with the “blue shifting” effect, in which light is squeezed to shorter wavelengths as it travels toward us in the same way that a police car’s siren squeals at higher frequencies as it heads toward you. Another reason has to do with the enormous speed of the black hole.

    The brighter black hole is, in fact, traveling at nearly seven percent the speed of light — in other words, really fast. Though it takes the black hole five years to orbit its companion, it is traveling vast distances. It would be as if a black hole lapped our entire solar system from the outer fringes, where the Oort cloud of comets lies, in just five years. At speeds as high as this, which are known as relativistic, the light becomes boosted and brighter.

    D’Orazio and colleagues modeled this effect based on a previous Caltech paper and predicted how it should look in ultraviolet light. They determined that, if the periodic brightening and dimming previously seen in the visible light is indeed due to the relativistic boosting effect, then the same periodic behavior should be present in ultraviolet wavelengths, but amplified 2.5 times. Sure enough, the ultraviolet light from GALEX and Hubble matched their predictions.

    “We are strengthening our ideas of what’s going on in this system and starting to understand it better,” said Zoltan Haiman, a co-author from Columbia University who conceived the project.

    The results will also help researchers understand how to find even closer-knit merging black holes in the future, what some consider the holy grail of physics and the search for gravitational waves. In the final moments before the ultimate union of two black holes, when they are tightly spinning around each other like ice skaters in a “death spiral,” they are predicted to send out ripples in space and time. These so-called gravitational waves, whose existence follows from Albert Einstein’s gravity theory published 100 years ago, hold clues about the fabric of our universe.

    The findings are also a doorway to understanding other merging black holes across the universe, a widespread population that is only now beginning to yield its secrets.

    The California Institute of Technology in Pasadena led the Galaxy Evolution Explorer mission, which ended in 2013 after more than a decade of scanning the skies in ultraviolet light. NASA’s Jet Propulsion Laboratory, also in Pasadena, managed the mission and built the science instrument. JPL is managed by Caltech for NASA.

    The Hubble Space Telescope is a project of international cooperation between NASA and ESA (European Space Agency). NASA’s Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore, Maryland, conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy in Washington.

    For more information about GALEX, visit:

    http://www.nasa.gov/galex

    http://www.galex.caltech.edu

    For more information on the Hubble Space Telescope, visit:

    http://www.nasa.gov/hubble

    See the full article here .

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    NASA JPL Campus

    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 2:18 pm on March 26, 2015 Permalink | Reply
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    From JPL: “Astronomers Upgrade Their Cosmic Light Bulbs” 

    JPL

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

    1
    A new study analyzes several sites where dead stars once exploded. Image credit: SDSS

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

    The brilliant explosions of dead stars have been used for years to illuminate the far-flung reaches of our cosmos. The explosions, called Type Ia supernovae, allow astronomers to measure the distances to galaxies and measure the ever-increasing rate at which our universe is stretching apart.

    But these tools aren’t perfect. In the cosmic hardware store of our universe, improvements are ongoing. In a new report, appearing March 27 in the journal Science, astronomers identify the best, top-of-the-line Type Ia supernovae for measuring cosmic distances, pushing other, more clunky tools to the back of the shelf.

    Using archived data from NASA’s Galaxy Evolution Explorer (GALEX), scientists show that a particular class of Type Ia supernovae that occur near youthful stars can improve these measurements with a precision of more than two times that achieved before.

    NASA Galex telescope
    GALEX

    “We have discovered a population of Type Ia supernovae whose light output depends very precisely on how quickly they fade, making it possible to measure very exact distances to them,” said Patrick Kelly of the University of California, Berkeley, lead author of the new study. “These supernovae are found close to populations of bright, hot young stars.”

    The findings will help light the way to understanding dark energy, one of the greatest mysteries in the field of cosmology, the study of the origin and development of the universe. Dark energy is the leading culprit behind the baffling acceleration of our cosmos, a phenomenon discovered in 1998. The acceleration was uncovered when astronomers observed that galaxies are pulling away from each other at increasing speeds.

    The key to measuring this acceleration — and thus the nature of dark energy — lies with Type Ia supernovae, which work much like light bulbs strung across space. Imagine lining up 60-watt light bulbs across a field and standing at one end. The farthest light bulb wouldn’t appear as bright as the closest one due to its distance. Since you know how bright the light bulb inherently is, you can use the extent of its dimming to figure out the distance.

    Type Ia supernovae, also referred to as “standard candles,” work in a similar way because they consistently shine with about the same amount of light. While the process that leads to these explosions is still not clear, they occur when the burnt-out core of a star, called a white dwarf, blasts apart in a regular way, briefly lighting up the host galaxy.

    However, the explosions aren’t always precisely uniform. They can differ considerably depending on various factors, which appear to be connected to the environments and histories of the exploding stars. It’s as if our 60-watt bulbs sometimes give off 55 watts of light, skewing distance measurements.

    Kelly and his team investigated the reliability of these tools by analyzing the surroundings of nearly 100 previous Type Ia explosions. They used data from GALEX, which detects ultraviolet light. Populations of hot, young stars in galaxies will shine brightly with ultraviolet light, so GALEX can distinguish between young and older star-forming communities.

    The results showed that the Type Ia supernovae affiliated with the hot, young stars were significantly more reliable at indicating distances than their counterparts.

    “These explosions are likely the result of youthful white dwarfs,” said Kelly.

    By focusing on this particular brand of Type Ia tools, astronomers will be able to, in the future, make even sharper measurements of the size and scale of our universe. According to the science team, this class of tools could work at distances up to six billion light-years away, and perhaps farther.

    “GALEX surveyed the entire sky, allowing past and future eruptions of these high-quality standard candles to be identified easily,” said Don Neill, a member of the GALEX team at the California Institute of Technology in Pasadena, not affiliated with the study. “Any improvement in the standard candles will have a direct impact on theories of dark energy, allowing us to home in on this mysterious force propelling the acceleration of the universe.”

    Caltech led the Galaxy Evolution Explorer mission and was responsible for science operations and data analysis. The mission ended in 2013 after more than a decade of scanning the skies in ultraviolet light. NASA’s Jet Propulsion Laboratory in Pasadena, California, managed the mission and built the science instrument. The mission was developed under NASA’s Explorers Program managed by the Goddard Space Flight Center, Greenbelt, Maryland. Researchers sponsored by Yonsei University in South Korea and the Centre National d’Etudes Spatiales (CNES) in France collaborated on this mission. ?

    Graphics and additional information about the Galaxy Evolution Explorer are online at:

    http://www.nasa.gov/galex

    http://www.galex.caltech.edu

    See the full article here.

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    NASA JPL Campus

    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, 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 5:44 pm on October 31, 2013 Permalink | Reply
    Tags: , , , , NASA Galex,   

    From NASA/JPL at Caltech: “Galaxy Growth Examined Like Rings of a Tree” 

    October 31, 2013
    Whitney Clavin 818-354-4673
    Jet Propulsion Laboratory, Pasadena, Calif.
    whitney.clavin@jpl.nasa.gov

    — Like tree rings, inner and outer portions of a galaxy’s disk are a historical record
    — Two NASA missions find evidence that star formation bursts started in galaxy centers and spread outward
    — Unexplained ultraviolet light might come from a late phase in the lives of older stars

    gg

    Watching a tree grow might be more frustrating than waiting for a pot to boil, but luckily for biologists, there are tree rings. Beginning at a tree trunk’s dense core and moving out to the soft bark, the passage of time is marked by concentric rings, revealing chapters of the tree’s history.

    Galaxies outlive trees by billions of years, making their growth impossible to see. But like biologists, astronomers can read the rings in a galaxy’s disk to unravel its past. Using data from NASA’s Wide-field Infrared Survey Explorer (WISE) and Galaxy Evolution Explorer (GALEX), scientists have acquired more evidence for the “inside-out” theory of galaxy growth, showing that bursts of star formation in central regions were followed one to two billion years later by star birth in the outer fringes.

    “Initially, a rapid star-forming period formed the mass at the center of these galaxies, followed later by a star-forming phase in the outer regions. Eventually, the galaxies stop making stars and become quiescent,” said Sara Petty of Virginia Tech, Blacksburg, Va., lead author of a paper appearing in the October 2013 issue of the Astronomical Journal. “This later star-forming phase could have been caused by minor mergers with gas-rich neighbors, which provide the fuel for new stars.”

    The discovery may also solve a mystery of elderly galaxies. The galaxies in the study, known as “red and dead” for their red color and lack of new star births, have a surprising amount of ultraviolet light emanating from the outer regions. Often, ultraviolet light is generated by hot, young stars, but these galaxies were considered too old to host such a young population.

    The solution to the puzzle is likely hot, old stars. Petty and colleagues used a new multi-wavelength approach to show that the unexplained ultraviolet light appears to be coming from a late phase in the lives of older stars, when they blow off their outer layers and heat up.

    GALEX and WISE turned out to be the ideal duo for the study. GALEX was sensitive to the ultraviolet light, whereas WISE sees the infrared light coming from older stars. GALEX is no longer operating, but WISE was recently reactivated to hunt asteroids, a project called NEOWISE (see http://www.jpl.nasa.gov/news/news.php?release=2013-257 ). Both telescopes have large fields of view, allowing them to easily capture images of entire galaxies.

    “The synergy between GALEX and WISE produces a very sensitive measurement of where the hot, older stars reside in these red-and-dead galaxies,” said Don Neill, co-author of the paper from the California Institute of Technology, Pasadena. “This allows us to map the progress of star formation within each galaxy.”

    Ned Wright of UCLA, a co-author of the study and the principal investigator of WISE before it was reactivated, compares the multi-wavelength range of the two telescopes to musical notes, “WISE itself covers the equivalent of a three-octave range, while WISE and GALEX together cover a seven-octave range.”

    See the full article here.

    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.

    Caltech Logo
    jpl


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  • richardmitnick 9:21 pm on January 10, 2013 Permalink | Reply
    Tags: , , , , , NASA Galex   

    From NASA Galex: “NASA’s GALEX Reveals the Largest-Known Spiral Galaxy 

    NASA Galex Banner

    NASA Galex telescope

    Galaxy Evolution Explorer (Galex)

    This composite of the giant barred spiral galaxy NGC 6872 combines visible light images from the European Southern Observatory’s Very Large Telescope with far-ultraviolet (1,528 angstroms) data from NASA’s GALEX and 3.6-micron infrared data acquired by NASA’s Spitzer Space Telescope. A previously unsuspected tidal dwarf galaxy candidate (circled) appears only in the ultraviolet, indicating the presence of many hot young stars. IC 4970, the small disk galaxy interacting with NGC 6872, is located above the spiral’s central region. The spiral is 522,000 light-years across from the tip of one outstretched arm to the tip of the other, which makes it about 5 times the size of our home galaxy, the Milky Way. Images of lower resolution from the Digital Sky Survey were used to fill in marginal areas not covered by the other data.

    galaxy
    Credit: NASA’s Goddard Space Flight Center/ESO/JPL-Caltech/DSS

    The spectacular barred spiral galaxy NGC 6872 has ranked among the biggest stellar systems for decades. Now a team of astronomers from the United States, Chile and Brazil has crowned it the largest-known spiral, based on archival data from NASA’s Galaxy Evolution Explorer (GALEX) mission, which has since been loaned to the California Institute of Technology, Pasadena, Calif.

    Measuring tip-to-tip across its two outsized spiral arms, NGC 6872 spans more than 522,000 light-years, making it more than five times the size of our Milky Way galaxy.

    ‘Without GALEX’s ability to detect the ultraviolet light of the youngest, hottest stars, we would never have recognized the full extent of this intriguing system,’ said lead scientist Rafael Eufrasio, a research assistant at NASA’s Goddard Space Flight Center in Greenbelt, Md., and a doctoral student at Catholic University of America in Washington. He presented the findings Thursday at the American Astronomical Society meeting in Long Beach, Calif.”

    See the full article here.

    NASA Goddard

    The Galaxy Evolution Explorer (GALEX) is an orbiting ultraviolet space telescope launched on April 28, 2003. NASA cut off financial support for operations of GALEX in early February 2011 as it was ranked lower than other projects which were seeking a limited supply of funding. The California Institute of Technology negotiated to transfer control of GALEX and its associated ground control equipment to the California Institute of Technology in keeping with the Stevenson-Wydler Technology Innovation Act. Under this Act, excess research equipment owned by the US government can be transferred to educational institutions and non-profit organizations.[3] In May 2012, GALEX operations were transferred to Caltech.

    Caltech Logo

     
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