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  • richardmitnick 3:44 pm on June 14, 2016 Permalink | Reply
    Tags: , FU Orionis Gluttonous Star May Hold Clues to Planet Formation, , ,   

    From JPL-Caltech: “Gluttonous Star May Hold Clues to Planet Formation” 

    NASA JPL Banner

    JPL-Caltech

    June 14, 2016
    Elizabeth Landau
    Jet Propulsion Laboratory, Pasadena, Calif.
    818-354-6425
    elizabeth.landau@jpl.nasa.gov

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    The brightness of outbursting star FU Orionis has been slowly fading since its initial flare-up in 1936. Researchers found that it has dimmed by about 13 percent in short infrared wavelengths from 2004 (left) to 2016 (right). Credit: NASA/JPL-Caltech

    In 1936, the young star FU Orionis began gobbling material from its surrounding disk of gas and dust with a sudden voraciousness. During a three-month binge, as matter turned into energy, the star became 100 times brighter, heating the disk around it to temperatures of up to 12,000 degrees Fahrenheit (7,000 Kelvin). FU Orionis is still devouring gas to this day, although not as quickly.

    This brightening is the most extreme event of its kind that has been confirmed around a star the size of the sun, and may have implications for how stars and planets form. The intense baking of the star’s surrounding disk likely changed its chemistry, permanently altering material that could one day turn into planets.

    “By studying FU Orionis, we’re seeing the absolute baby years of a solar system,” said Joel Green, a project scientist at the Space Telescope Science Institute, Baltimore, Maryland. “Our own sun may have gone through a similar brightening, which would have been a crucial step in the formation of Earth and other planets in our solar system.”

    Visible light observations of FU Orionis, which is about 1,500 light-years away from Earth in the constellation Orion, have shown astronomers that the star’s extreme brightness began slowly fading after its initial 1936 burst. But Green and colleagues wanted to know more about the relationship between the star and surrounding disk. Is the star still gorging on it? Is its composition changing? When will the star’s brightness return to pre-outburst levels?

    To answer these questions, scientists needed to observe the star’s brightness at infrared wavelengths, which are longer than the human eye can see and provide temperature measurements.

    Green and his team compared infrared data obtained in 2016 using the Stratospheric Observatory for Infrared Astronomy, SOFIA, to observations made with NASA’s Spitzer Space Telescope in 2004.

    NASA/DLR SOFIA
    NASA/DLR SOFIA

    NASA/Spitzer Telescope
    NASA/Spitzer Telescope

    SOFIA, the world’s largest airborne observatory, is jointly operated by NASA and the German Aerospace Center and provides observations at wavelengths no longer attainable by Spitzer. The SOFIA data were taken using the FORCAST instrument (Faint Object infrared Camera for the SOFIA Telescope).

    NASA/SOFIA Forcast
    NASA/SOFIA Forcast

    “By combining data from the two telescopes collected over a 12-year interval, we were able to gain a unique perspective on the star’s behavior over time,” Green said. He presented the results at the American Astronomical Society meeting in San Diego, this week.

    Using these infrared observations and other historical data, researchers found that FU Orionis had continued its ravenous snacking after the initial brightening event: The star has eaten the equivalent of 18 Jupiters in the last 80 years.

    The recent measurements provided by SOFIA inform researchers that the total amount of visible and infrared light energy coming out of the FU Orionis system decreased by about 13 percent over the 12 years since the Spitzer observations. Researchers determined that this decrease is caused by dimming of the star at short infrared wavelengths, but not at longer wavelengths. That means up to 13 percent of the hottest material of the disk has disappeared, while colder material has stayed intact.

    “A decrease in the hottest gas means that the star is eating the innermost part of the disk, but the rest of the disk has essentially not changed in the last 12 years,” Green said. “This result is consistent with computer models, but for the first time we are able to confirm the theory with observations.”

    Astronomers predict, partly based on the new results, that FU Orionis will run out of hot material to nosh on within the next few hundred years. At that point, the star will return to the state it was in before the dramatic 1936 brightening event. Scientists are unsure what the star was like before or what set off the feeding frenzy.

    “The material falling into the star is like water from a hose that’s slowly being pinched off,” Green said. “Eventually the water will stop.”

    If our sun had a brightening event like FU Orionis did in 1936, this could explain why certain elements are more abundant on Mars than on Earth. A sudden 100-fold brightening would have altered the chemical composition of material close to the star, but not as much farther from it. Because Mars formed farther from the sun, its component material would not have been heated up as much as Earth’s was.

    At a few hundred thousand years old, FU Orionis is a toddler in the typical lifespan of a star. The 80 years of brightening and fading since 1936 represent only a tiny fraction of the star’s life so far, but these changes happened to occur at a time when astronomers could observe.

    “It’s amazing that an entire protoplanetary disk can change on such a short timescale, within a human lifetime,” said Luisa Rebull, study co-author and research scientist at the Infrared Processing and Analysis Center (IPAC), based at Caltech, Pasadena, California.

    Green plans to gain more insight into the FU Orionis feeding phenomenon with NASA’s James Webb Space Telescope, which will launch in 2018.

    NASA/ESA/CSA Webb Telescope annotated
    NASA/ESA/CSA Webb Telescope annotated

    SOFIA has mid-infrared high-resolution spectrometers and far-infrared science instrumentation that complement Webb’s planned near- and mid-infrared capabilities. Spitzer is expected to continue exploring the universe in infrared light, and enabling groundbreaking scientific investigations, into early 2019.

    NASA’s Jet Propulsion Laboratory, Pasadena, California, manages the Spitzer Space Telescope mission for NASA. Science operations are conducted at the Spitzer Science Center at Caltech. Spacecraft operations are based at Lockheed Martin Space Systems Company, Littleton, Colorado. Data are archived at the Infrared Science Archive housed at IPAC at Caltech. Caltech manages JPL for NASA.

    SOFIA is a joint project of NASA and the German Aerospace Center (DLR). The aircraft is based at NASA Armstrong Flight Research Center’s facility in Palmdale, California. NASA’s Ames Research Center in Moffett Field, California, manages the SOFIA science and mission operations in cooperation with the Universities Space Research Association (USRA) headquartered in Columbia, Maryland, and the German SOFIA Institute (DSI) at the University of Stuttgart.

    For more information about Spitzer, visit:

    http://www.nasa.gov/spitzer

    http://spitzer.caltech.edu

    For more information about SOFIA, visit:

    http://www.nasa.gov/sofia

    http://www.dlr.de/en/sofia

    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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    NASA image

     
  • richardmitnick 3:33 pm on June 10, 2016 Permalink | Reply
    Tags: , , Diane Souvaine-Vice Chair, Maria Zuber-Chair, National Science Board, ,   

    From NSF: Women in Science “The National Science Board taps Maria Zuber as its chairperson and Diane Souvaine for vice chairperson” 

    nsf
    National Science Foundation

    1
    National Science Board

    May 24, 2016 [Just appeared in social media.]

    1
    Left, Maria Zuber, Chair; right, Diane Souvaine, Vice Chair

    For the first time in National Science Foundation (NSF) history, women hold the positions of director and National Science Board (NSB) chair, and vice chair. During its May meeting, the board, which serves as the governing body for NSF, elected Maria Zuber, vice president for research at the Massachusetts Institute of Technology, as chair and Diane Souvaine, vice provost for research at Tufts University, as vice chair. They replace Dan Arvizu and Kelvin Droegemeier, who both rotated off the board after serving 12 years, the last four as chair and vice chair, respectively.

    Zuber’s research bridges planetary geophysics and the technology of space-based laser and radio systems, and she has published over 200 papers. She has held leadership roles associated with scientific experiments or instrumentation on nine NASA missions and remains involved with six of these missions. She is a member of the National Academy of Sciences and American Philosophical Society and is a fellow for the American Academy of Arts and Sciences, the American Association for the Advancement of Science, the Geological Society and the American Geophysical Union. In 2002, Discover magazine named her one of the 50 most important women in science. Zuber served on the Presidential Commission on the Implementation of United States Space Exploration Policy in 2004.

    NSF Director and NSB member ex officio France Córdova said, “I am delighted to say, on behalf of NSF that we are thrilled with Dr. Zuber’s election as chair and Dr. Souvaine’s election as vice chair of the National Science Board. As Dr. Zuber is a superb scientist and recognized university leader, she has the skills needed to help guide the agency’s policies and programs. Coupled with Dr. Souvaine’s background in computer science, exemplary leadership skills, and expertise in budget oversight and strategy, NSB is well-positioned for the coming years. I look forward to working with both leaders as NSF launches new big ideas in science and engineering.”

    Zuber is in her fourth year on the board and has served on its Committee on Strategy and Budget, which advises on NSF’s strategic direction and reviews the agency’s budget submissions.

    “It is a privilege to lead the National Science Board and to promote NSF’s bold vision for research and education in science and engineering,” Zuber said. “The outcomes of discovery science inspire the next generation and yield the knowledge that drives innovation and national competitiveness, and contribute to our quality of life. NSB is committed to working with director Córdova and her talented staff to assure that the very best ideas based on merit review are supported and that exciting, emerging opportunities — many at the intersection of disciplines — are pursued.”

    Souvaine is in her second term on the NSB and has served as chair of its Committee on Strategy and Budget, chair of its Committee on Programs and Plans, and as a member of its Committee on Audit and Oversight, all of which provide strategic direction, and oversight and guidance on NSF projects and programs. In addition, she co-chaired NSB’s Task Force on Mid-Scale Research and served three years on the Executive Committee.

    A theoretical computer scientist, Souvaine’s research in computational geometry has commercial applications in materials engineering, microchip design, robotics and computer graphics. She was elected a fellow of the Association for Computing Machinery for her research and for her service on behalf of the computing community. A founding member, Souvaine served for over two years in the directorate of the NSF Science and Technology Center on Discrete Mathematics and Theoretical Computer Science that originally spanned Princeton University, Rutgers University, Bell Labs and Bell Communications Research. She also works to enhance pre-college mathematics and foundations of computing education and to advance opportunities for women and minorities in mathematics, science and engineering.

    “I am truly honored and humbled by this vote of confidence from such esteemed colleagues. I do not take this responsibility lightly,” Souvaine said. “The board is proud of NSF’s accomplishments over its 66 years, from the discovery of gravitational waves at LIGO to our biennial Science and Engineering Indicators report on the state of our nation’s science and engineering enterprise. I look forward to working with Congress, the Administration, the science and education communities, and NSF staff to continue the agency’s legacy in advancing the progress of science.”

    Jointly, the 24-member board and the director pursue the goals and function of the foundation. NSB establishes NSF policies within the framework of applicable national policies set forth by the President and Congress. NSB identifies issues critical to NSF’s future, approves the agency’s strategic budget directions and the annual budget submission to the Office of Management and Budget, and new major programs and awards. The board also serves as an independent body of advisers to both the President and Congress on policy matters related to science and engineering and education in science and engineering. In addition to major reports, NSB publishes policy papers and statements on issues of importance to U.S. science and engineering.

    The President appoints board members, selected for their eminence in research, education or public service and records of distinguished service and who represent a variety of science and engineering disciplines and geographic areas. Board members serve six-year terms and the President may reappoint members for a second term. NSF’s director is an ex officio 25th member of the board.

    See the full article here .

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    The National Science Foundation (NSF) is an independent federal agency created by Congress in 1950 “to promote the progress of science; to advance the national health, prosperity, and welfare; to secure the national defense…we are the funding source for approximately 24 percent of all federally supported basic research conducted by America’s colleges and universities. In many fields such as mathematics, computer science and the social sciences, NSF is the major source of federal backing.

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  • richardmitnick 2:51 pm on June 10, 2016 Permalink | Reply
    Tags: 80 Percent of Humankind Can’t See the Milky Way Anymore, , , ,   

    From natgeo: “80 Percent of Humankind Can’t See the Milky Way Anymore” 

    National Geographic

    National Geographics

    June 10, 2016
    Michelle Z. Donahue

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    The Milky Way illuminates the sky over Dinosaur National Monument, which spreads across Colorado and Utah. Photograph by Dan Duriscoe

    The Milky Way galaxy, that torrent of stars that slashes across a deeply darkened night sky, has been a deep well of inspiration from humanity’s earliest days. The ancient Egyptians saw it as a pool of cow’s milk, while in Hindu mythology the arcing galactic arm was likened to a dolphin swimming through the sky. Countless scientists, philosophers, and artists, including Galileo, Aristotle, and Vincent Van Gogh, have drawn upon the galaxy as their muse. (Read “How Much Does the Milky Way Weigh?”)

    But a new atlas of the night sky across the entire globe shows that more than 80 percent of the planet’s land areas—and 99 percent of the population of the United States and Europe—live under skies so blotted with man-made light that the Milky Way has become virtually invisible.

    Fabio Falchi, a researcher at the Light Pollution Science and Technology Institute (ISTIL) in Thiene, Italy, announced Friday the release of a new survey that quantifies nighttime sky quality for every region in the world. Produced using over 35,000 ground-based observations and six months of data from 2014 collected with the Suomi National Polar-orbiting Partnership (NPP) satellite, the atlas is an update to a 2001 work and shows the planet’s darkest and brightest locations in stark contrast.

    NASA/Goddard Suomi NPP satellite
    NASA/Goddard Suomi NPP satellite

    Woe to Singapore, a place of eternal twilight, with the entire population living under skies so bright their eyes cannot fully adjust to night vision, let alone see the Milky Way. Kuwait, Qatar, and the United Arab Emirates have it nearly as bad.

    On the other hand, more than 75 percent of the population of Chad, the Central African Republic, and Madagascar live under near-pristine skies, or places where background light represents less than one percent of the sky’s overall brightness. And according to Falchi’s analysis, residents of the Azores have the distinction of living the farthest from land with unspoiled skies: They’d have to travel nearly 1,100 miles, to the western Sahara, to experience an ancestrally darkened landscape (unless they travel out into the ocean).

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    Light pollution clouds the view over Joshua Tree National Park, California. Photograph by Dan Duriscoe

    “In the first atlas we had a hint of what was happening, but these numbers are shocking,” Falchi says. “We have lost the connection with our roots, of literature, of philosophy, of science, of religion—all are connected with the contemplation of the night sky. A new generation can no longer appreciate this beauty.” (“See a Stunning New View of the Milky Way.”)

    Study co-author Dan Duriscoe, a physical scientist with the National Park Service’s Natural Sounds and Night Skies Division, has worked in the Park Service for 36 years and has collected light measurements in national parks since 1994. On the East Coast, apart from a few scattered points in West Virginia, Pennsylvania, and New England, it’s extremely difficult to get to a place with an unfettered view of stars.

    “People could get that experience closer to home decades ago, but now they’re forced out into Utah or Death Valley or Yellowstone, somewhere far from their backyards,” Duriscoe says. “There’s an increased public awareness of how this is a rare experience and becoming one that will cost them some money to go see.”

    High-Tech Eyes on the Sky

    Sweeping over the Earth’s poles 14 times a day, the Suomi satellite generates a complete global set of high-resolution day and night images every 24 hours. Falchi, along with ISTIL colleague Pierantonio Cinzano, worked with data from partners including the National Park Service (NPS) and the National Oceanographic and Atmospheric Administration (NOAA) to produce the atlas. The 2001 atlas looked at only light escaping from Earth into space, while the new data reveal where light is reflected from the sky down to the Earth’s surface. (Read “Graveyard of Stars May Lie at Milky Way’s Center.”)

    Falchi plans to release a print version of the atlas, and an interactive digital atlas, similar to one from 2006 produced using the 2001 data, is also in the works.

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    A map illustrates light pollution in North and South America. Illustration by Fabio Falchi, Google Earth

    Chris Elvidge, a co-author of the study and a scientist with NOAA’s National Centers for Environmental Information, says he expects that the satellite data and analysis will be useful not only for astronomers, who have a vested interest in a dark night sky, but also for biologists studying light impacts on nocturnal organisms, medical researchers interested in the human health effects, and city planners.

    One drawback of the satellite’s imaging instruments is limited detection of the blue and violet parts of the visible spectrum—the very zone where white LEDs would show up on satellite scans. Though highly efficient, white LEDs can be excessively bright, and as municipalities begin to install them in streetlights and for other outdoor purposes, the impact of LEDs may actually worsen overall light pollution in the long run.

    “Several cities have jumped on the LED bandwagon without getting their citizens’ approval,” says Connie Walker, an astronomer with the National Optical Astronomy Observatory in Tucson, Arizona, and a board member of the International Dark-Sky Association. Jurisdictions interested in effectively reducing light pollution can turn to the two atlases to research before-and-after maps, and compare what’s worked and what hasn’t, she says.

    “This atlas affords a consistent way of comparing light pollution in different areas of the world over the last 15 years,” she says.

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    This map shows light pollution in the Eastern Hemisphere. Illustration by Fabio Falchi, Google Earth

    Falchi’s work, done completely in his off hours as a labor of love, helps put the extent of the problem into perspective, Duriscoe says.

    “To tackle this on a global scale, nobody else before has attempted it,” he says. “When you can stand back and look at the whole Earth and the impact of our modern lifestyle on the ability of all cultures to enjoy the natural nocturnal environment, it shows how we just take it for granted.”

    Protecting Natural Cycles

    At one time, communities with large telescopes, like the Palomar Observatory outside of San Diego, California, prided themselves on their efforts to protect the night sky, though that attitude seems to have waned over the last several decades, Duriscoe notes. Now, however, with more research emerging about the negative impacts on humans of overexposure to light, there has been an uptick of interest in combating the 24-hour lifestyle.

    Falchi has been personally involved in his own community in changing approaches to outdoor lighting. As the current president of the nonprofit CieloBuio dark skies advocacy organization, he spearheaded a petition effort in the late 1990s to enact lighting reform laws in Lombardia, the region where he lives and works. With controls on the types of new fixtures being installed and limits on light intensity in given areas, despite a twofold increase in the number of new lights, light-pollution levels in the region have remained constant from 2000 to today.

    Though much of Italy is now governed by similar laws, it’s still only a start, Falchi says.

    “This is not a sufficient measure for controlling light pollution, but simply a stop in the increase,” he adds. “For almost all other pollutants—chemical, particulate, carbon monoxide, or anything else, graphs show that almost all of them have decreased over the last 20 years. We need to decrease pollution from light as well.”

    See the full article here .

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    The National Geographic Society has been inspiring people to care about the planet since 1888. It is one of the largest nonprofit scientific and educational institutions in the world. Its interests include geography, archaeology and natural science, and the promotion of environmental and historical conservation.

     
  • richardmitnick 1:27 pm on June 10, 2016 Permalink | Reply
    Tags: , , , T-Tauri stars   

    From CfA: “T-Tauri Stars” 

    Harvard Smithsonian Center for Astrophysics


    Center For Astrophysics

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    Young stars and nebulosity in Chamaeleon, a constellation visible predominantly in the southern sky. A new study of young (T-Tauri) stars in this region has determined their ages as being between about five – six million years old, as well as determining other properties. FORS Team, 8.2-meter VLT Antu, ESO

    ESO/VLT at Cerro Paranal, Chile
    ESO/VLT at Cerro Paranal, Chile

    ESO/FORS1
    “ESO/FORS1

    A newborn star typically goes through four stages of adolescence. It begins life as a protostar still enshrouded in its natal molecular cloud, accreting new material and developing a proto-planetary disc. Slowly, stellar winds and radiation blow away the surrounding shell of gas and dust, and the third stage, when the surrounding envelope has cleared, is called the T-Tauri phase. T-Tauri stars (the class is named after the first star of this type that was so identified) are less than about ten million years old, and provide astronomers with promising candidates in which to study the early lives of stars and planets. They were among the first young stars to be identified because the earlier stages, still embedded in their birth clouds, were blocked from optical observations by the dust. In the fourth stage, the disk stops accreting and the source’s radiation comes from the star’s photosphere. T-Tauri stars produce strong X-rays, primarily by what is thought to be coronal activity much like the coronal activity in our own Sun, although in some cases a component might be coming from hot material in the dusty disk.

    Measurements of T-Tauri circumstellar disks provide important tests for theories of planet formation and migration. Near-infrared results, for example, sample the hotter temperature dust grains, and can reveal the presence of gaps in the disk (perhaps cleared by massive planets) when an expected ring of warm dust around the star is not detected. Astronomers during the past few decades have been able to use infrared space telescopes like Spitzer to probe T-Tauri disks, but there are still many puzzles, in particular about the mechanisms responsible for the accretion, the subsequent dissipation of material, and the evolutionary ages when these processes occur.

    CfA astronomer Philip Cargile was a member of a team of seven scientists studying the evolution of these stars and their disks. They took detailed optical observations (including spectra) of a sample of twenty-five X-ray selected T-Tauri stars in two nearby star-forming clouds to derive their ages and stellar masses. They find that most of the sources in one cloud are between about five and six million year old; a couple turn out to be more like twenty-five million years old and can now be excluded from the T-Tauri class. In the other cloud, most of the sources are younger than about ten million years. The results agree well with theoretical models and other observations. Perhaps more usefully, the results help to identify true T-Tauri stars with disks that would be suitable for imaging observations with a new generation of large telescopes.

    Reference(s):

    Fundamental Stellar Parameters for Selected T-Tauri Stars in the Chamaeleon and Rho Ophiuchus Star-Forming Regions,” D.J. James, A.N. Aarnio, A.J.W. Richert, P.A. Cargile, N.C. Santos, C.H.F. Melo, and J. Bouvier, MNRAS 459, 1363.

    See the full article here .

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    The Center for Astrophysics combines the resources and research facilities of the Harvard College Observatory and the Smithsonian Astrophysical Observatory under a single director to pursue studies of those basic physical processes that determine the nature and evolution of the universe. The Smithsonian Astrophysical Observatory (SAO) is a bureau of the Smithsonian Institution, founded in 1890. The Harvard College Observatory (HCO), founded in 1839, is a research institution of the Faculty of Arts and Sciences, Harvard University, and provides facilities and substantial other support for teaching activities of the Department of Astronomy.

     
  • richardmitnick 12:16 pm on June 10, 2016 Permalink | Reply
    Tags: , , ,   

    From Ethan Siegel: “NASA’s big mistake: LIGO’s merging black holes were invisible after all” 

    Ethan Siegel
    6.10.16

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    Image Credit: SXS, the Simulating eXtreme Spacetimes (SXS) project (http://www.black-holes.org).

    The gravitational waves were real. But earlier announcements that X-rays and gamma-rays were detected, too? Not so much.

    What’s really exciting is what comes next. I think we’re opening a window on the universe — a window of gravitational wave astronomy.” -Dave Reitze

    On September 14, 2015, a tiny effect lasting 200 milliseconds passed through the Earth at the speed of light. The entire planet compressed and expanded in two mutually perpendicular directions by less than the width of a proton, oscillating back and forth roughly seven times in that span. And in two detectors separated by 2,000 miles, an interference pattern formed by two isolated lasers, reflected back-and-forth in a vacuum and then brought together again, gave us the telltale explanation for this effect.

    Caltech/MIT   Advanced Ligo Hanford, WA, USA installation
    Caltech/MIT Advanced aLigo Hanford, WA, USA installation

    Caltech/MIT Advanced aLigo detector in Livingston, LA, USA
    Caltech/MIT Advanced aLigo detector installation in Livingston, LA, USA

    From 1.3 billion light years away, two black holes some 30 times the mass of the Sun had spiraled into one another, merging together and sending energetic ripples through the fabric of space itself. For the first time, a gravitational wave — one of the oldest unverified predictions of Einstein’s General Relativity — had been directly detected.

    Gravitational waves. Credit: MPI for Gravitational Physics/W.Benger-Zib
    Gravitational waves. Credit: MPI for Gravitational Physics/W.Benger-Zib

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    Image credit: ESA–C.Carreau, of the “ripple” effect on spacetime that a passing gravitational wave imparts.

    Optical telescopes didn’t see anything, as expected. Merging black holes weren’t anticipated to emit any light, unlike merging stars (which create a larger star), white dwarfs (which create a supernova), or neutron stars (which are thought to create a gamma ray burst); they should only be detectable by their gravitational wave signal. Yet there was a curious possible exception, as a team from NASA’s Fermi satellite claimed to detect gamma rays coincident with this event, offset by a meagre 0.4 seconds. An array of 14 crystal detectors on board — the Gamma-ray Burst detection Monitor (GBM) instrument — detected an unexpected burst of X-rays, and claimed there was only a 0.2% chance of a false positive.

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    This image, taken in May 2008 as the Fermi Gamma-ray Space Telescope was being readied for launch, highlights the detectors of its Gamma-ray Burst Monitor (GBM). The GBM is an array of 14 crystal detectors. Image credit: NASA/Jim Grossmann.

    While NASA was celebrating, however, cautious scientists all over the world were skeptical. Not only would this overthrow the leading theoretical models for black hole mergers, and not only does a 99.8% chance of success correspond only to a 3-σ significance (rather than the 5-σ significance typically required for a discovery in physics), but a complimentary satellite in orbit — the ESA’s INTEGRAL satellite — failed to see the corroborating evidence it should have if this signal were real.

    ESA/Integral
    ESA/Integral

    On the contrary, INTEGRAL searched through all the data and failed to find any interesting signal coincident with LIGO’s gravitational wave at all. Far from a definitive detection, this conflicting data raised more questions than it answered.

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    A marginal detection only is available for the gravitational wave event associated with LIGO’s detection on September 14, 2015. Image credit: D. Bagoly et al., 2016 (submitted to A&A), via http://arxiv.org/abs/1603.06611.

    Thanks to a new paper now available from J. Greiner, J.M. Burgess, V. Savchenko and H.-F. Yu, however, the apparent conflict may at last be resolved. The secret lies in understanding how the GBM instrument aboard NASA’s Fermi satellite actually works. Rather than measuring an absolute signal, it measures a steady, continuous background of photons over a large energy range. The spikes above that background, when they appear, can show us either a real, physical event (like a burst or merger), or they can simply be evidence of a random fluctuation that has no physical origin at all. If you use an imperfect algorithm for discriminating which fluctuations are physical vs. non-physical, you could wind up drawing invalid conclusions about what’s real and what’s phantasmal. The huge advance of the new paper, submitted to the Astrophysical Journal as a Letter, isn’t observational or theoretical, but rather statistical; it more robustly and successfully discriminates between normal noise and a burst of high-energy light from an astrophysical source.

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    Various statistical techniques analyzing the Fermi data. The original analysis (purple) shows a signal, but the improved analysis (orange) shows only something consistent with pure noise. Image credit: Figure 5 from J. Greiner, J.M. Burgess, V. Savchenko and H.-F. Yu, retrieved from the preprint at http://arxiv.org/abs/1606.00314.

    Above, you can see a number of different ways of reconstructing the apparent signal coincident with LIGO’s gravitational wave. The original Fermi team’s analysis is shown in purple: a clear detection. However, the superior reconstruction of this new paper is shown in orange, and lines up with both the raw data (blue) and also — more importantly — is consistent with a non-detection, meaning that there is no electromagnetic signal here. According to one of the paper’s authors, J. Michael Burgess, the original paper (claiming a detection) had some statistical flaws his team was able to spot, relating the following:

    When I saw the announcement and the paper, the spectrum looked like what I always see as background.

    After pulling his team together and developing some new analysis tools, they confirmed their suspicions:

    We instantly saw that we got a much different answer. The spectrum of the event was basically zero: nothing there.

    The new statistical technique developed by Burgess and his collaborators has proven to be incredibly powerful, successfully pulling out even faint gamma ray signals from noisy data and drastically reducing the number of false positives. By combining this new technique with the existing Fermi data, it should be possible to make huge strides forward in identifying true astrophysical events.

    Gamma ray burst artist depiction Credit NASA Swift Mary Pat Hrybyk-Keith and John Jones
    Gamma ray burst artist depiction Credit NASA Swift Mary Pat Hrybyk-Keith and John Jones

    It’s important to remember that there can and will be correlations in the future not only between gravitational waves and gamma rays, but between LIGO and Fermi’s GBM instrument. When asked for comment, Burgess said the following:

    “GBM is an amazing instrument and its synergy with LIGO provides an amazing way for us to view the Universe. The GBM team has made a huge effort for this, and when a neutron star merger happens nearby, it is very likely GBM and LIGO (and others) will see something… and this will be amazing!”

    But in order to make sure we aren’t fooling ourselves, we have to do it right. Collaboration between the teams — the Fermi team, the INTEGRAL team, and the gravitational wave teams — are incredibly important. But the necessity of calibrating the signals that multiple observatories will see is essential to getting the right results. Merging black holes may, in fact, sometimes lead to electromagnetic radiation, a possibility which future events will hopefully test. But the golden rule in situations like these is the null hypothesis: in the absence of extraordinary evidence, as is the case here, bet on exactly what the leading physics ideas predict.

    See the full article here .

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    “Starts With A Bang! is a blog/video blog about cosmology, physics, astronomy, and anything else I find interesting enough to write about. I am a firm believer that the highest good in life is learning, and the greatest evil is willful ignorance. The goal of everything on this site is to help inform you about our world, how we came to be here, and to understand how it all works. As I write these pages for you, I hope to not only explain to you what we know, think, and believe, but how we know it, and why we draw the conclusions we do. It is my hope that you find this interesting, informative, and accessible,” says Ethan

     
  • richardmitnick 11:32 am on June 10, 2016 Permalink | Reply
    Tags: , , , Jets from Merging Neutron Stars   

    From AAS NOVA: “Jets from Merging Neutron Stars” 

    AASNOVA

    Amercan Astronomical Society

    1
    Still from a simulation of the merger of two neutron stars. In this late stage of the simulation, the neutron stars have merged to form a black hole, which has launched a powerful jet. [Adapted from Ruiz et al. 2016]

    With the recent discovery of gravitational waves from the merger of two black holes, it’s especially important to understand the electromagnetic signals resulting from mergers of compact objects. New simulations successfully follow a merger of two neutron stars that produces a short burst of energy via a jet consistent with short gamma-ray burst (sGRB) detections.

    2
    Still from the authors’ simulation showing the two neutron stars, and their magnetic fields, before merger. [Adapted from Ruiz et al. 2016]

    Challenging System

    We have long suspected that sGRBs are produced by the mergers of compact objects, but this model has been difficult to prove. One major hitch is that modeling the process of merger and sGRB launch is very difficult, due to the fact that these extreme systems involve magnetic fields, fluids and full general relativity.

    Traditionally, simulations are only able to track such mergers over short periods of time. But in a recent study, Milton Ruiz (University of Illinois at Urbana-Champaign and Industrial University of Santander, Colombia) and coauthors Ryan Lang, Vasileios Paschalidis and Stuart Shapiro have modeled a binary neutron star system all the way through the process of inspiral, merger, and the launch of a jet.

    A Merger Timeline

    How does this happen? Let’s walk through one of the team’s simulations, in which dipole magnetic field lines thread through the interior of each neutron star and extend beyond its surface (like magnetic fields found in pulsars). In this example, the two neutron stars each have a mass of 1.625 solar masses.

    Simulation start (0 ms)
    Loss of energy via gravitational waves cause the neutron stars to inspiral.
    Merger (3.5 ms)
    The neutron stars are stretched by tidal effects and make contact. Their merger produces a hypermassive neutron star that is supported against collapse by its differential (nonuniform) rotation.
    Delayed collapse into a black hole (21.5 ms)
    Once the differential rotation is redistributed by magnetic fields and partially radiated away in gravitational waves, the hypermassive neutron star loses its support and collapses to a black hole.
    Plasma velocities turn around (51.5 ms)
    Initially the plasma was falling inward, but as the disk of neutron-star debris is accreted onto the black hole, energy is released. This turns the plasma near the black hole poles around and flings it outward.
    Magnetic field forms a helical funnel (62.5 ms)
    The fields near the poles of the black hole amplify as they are wound around, creating a funnel that provides the wall of the jet.
    Jet outflow extends to heights greater than 445 km (64.5 ms)
    The disk is all accreted and, since the fuel is exhausted, the outflow shuts off (within 100ms)

    Neutron-Star Success

    3
    Plot showing the gravitational wave signature for one of the authors’ simulations. The moments of merger of the neutron stars and collapse to a black hole are marked. [Adapted from Ruiz et al. 2016]

    These simulations show that no initial black hole is needed to launch outflows; a merger of two neutron stars can result in an sGRB-like jet. Another interesting result is that the magnetic field configuration doesn’t affect the formation of a jet: neutron stars with magnetic fields confined to their interiors launch jets as effectively as those with pulsar-like magnetic fields. The accretion timescale for both cases is consistent with the duration of an sGRB.

    While this simulation models milliseconds of real time, it’s enormously computationally challenging and takes months to simulate. The successes of this simulation represent exciting advances in numerical relativity, as well as in our understanding of the electromagnetic counterparts that may accompany gravitational waves.

    Bonus

    Check out this awesome video of the authors’ simulations. The colors differentiate the plasma density and the white lines depict the pulsar-like magnetic field that initially threads the two merging neutron stars. Watch as the neutron stars evolve through the different stages outlined above, eventually forming a black hole and launching a powerful jet. [Simulations and visualization by M. Ruiz, R. Lang, V. Paschalidis, S. Shapiro and the Illinois Relativity Group REU team: S. Connelly, C. Fan, A. Khan, and P. Wongsutthikoson]


    Access mp4 video here .

    Citation

    Milton Ruiz et al 2016 ApJ 824 L6. doi:10.3847/2041-8205/824/1/L6

    See the full article here .

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  • richardmitnick 11:21 am on June 10, 2016 Permalink | Reply
    Tags: , , , Laura Shou, ,   

    From Caltech: Women in Science “Shou Receives Fellowship for Graduate Studies in Germany” Laura Shou 

    Caltech Logo
    Caltech

    06/09/2016
    Lori Dajose

    1
    Laura Shou. Credit: Courtesy of L. Shou

    Laura Shou, a senior in mathematics, has received a Graduate Study Scholarship from the German Academic Exchange Service (DAAD) to pursue a master’s degree in Germany. She will spend one year at the Ludwig-Maximilians-Universität München and the Technische Universität München, studying in the theoretical and mathematical physics (TMP) program.

    The DAAD is the German national agency for the support of international academic cooperation. The organization aims to promote international academic relations and cooperation by offering mobility programs for students, faculty, and administrators and others in the higher education realm. The Graduate Study Scholarship supports highly qualified American and Canadian students with an opportunity to conduct independent research or complete a full master’s degree in Germany. Master’s scholarships are granted for 12 months and are eligible for up to a one-year extension in the case of two-year master’s programs. Recipients receive a living stipend, health insurance, educational costs, and travel.

    “As a math major, I was especially interested in the TMP course because of its focus on the interplay between theoretical physics and mathematics,” Shou says. “I would like to use mathematical rigor and analysis to work on problems motivated by physics. The TMP course at the LMU/TUM is one of the few programs focused specifically on mathematical physics. There are many people doing research in mathematical physics there, and the program also regularly offers mathematically rigorous physics classes.”

    At Caltech, Shou has participated in the Summer Undergraduate Research Fellowship (SURF) program three times, conducting research with Professor of Mathematics Yi Ni on knot theory and topology, with former postdoctoral fellow Chris Marx (PhD ’12) on mathematical physics, and with Professor of Mathematics Nets Katz on analysis. She was the president of the Dance Dance Revolution Club and a member of the Caltech NERF Club and the Caltech Math Club.

    Following her year in Germany, Shou will begin the mathematics PhD program at Princeton.

    See the full article here .

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    Caltech campus

    The California Institute of Technology (commonly referred to as Caltech) is a private research university located in Pasadena, California, United States. Caltech has six academic divisions with strong emphases on science and engineering. Its 124-acre (50 ha) primary campus is located approximately 11 mi (18 km) northeast of downtown Los Angeles. “The mission of the California Institute of Technology is to expand human knowledge and benefit society through research integrated with education. We investigate the most challenging, fundamental problems in science and technology in a singularly collegial, interdisciplinary atmosphere, while educating outstanding students to become creative members of society.”

     
  • richardmitnick 9:44 am on June 10, 2016 Permalink | Reply
    Tags: , , ,   

    From Quanta: Women in Science “An Explorer of Quantum Borderlands” Suchitra Sebastian 

    Quanta Magazine
    Quanta Magazine

    June 9, 2016
    Maggie McKee

    1
    Suchitra Sebastian is building a new lab to study exotic quantum behavior at Cambridge University. Philipp Ammon for Quanta Magazine

    Suchitra Sebastian is a fringe physicist. Not a crackpot — she lectures at the University of Cambridge and has published a string of papers in Science and Nature. But she likes to venture into the borderlands between forms of matter that other physicists have already explored. There, in the liminal space where the particles in a material begin to change from one configuration to another, new quantum effects appear. “A lot of it is really exciting phenomena that emerges before it’s theoretically predicted,” Sebastian said with delight.

    Last year, she and her colleagues discovered what appeared to be electrons looping their way through an insulator, a type of material that by definition prevents such movement. The observation, in a substance called samarium hexaboride, is still not understood. But Sebastian says one possibility is that what was looping was not electrons but an entirely new kind of subatomic building block.

    Interactions between electrons create wavelike disturbances — known as quasiparticles — that serve as the basic components of almost every complex material. The known quasiparticles tend to act like heavier versions of electrons, but not so in this case. “In samarium hexaboride, the possibility is that the electron itself has broken apart,” said Sebastian. “So instead of thinking of the electron as the building block, we would need to think of fractional parts of the electron as building blocks.” These fractional quasiparticles would create an entirely new way to understand the universe of materials.

    Sebastian herself moves between very different worlds. Before delving into science, she worked as a management consultant, and now she performs in experimental theater pieces when she’s not in the lab. “I kind of intensely do different things,” she says. “If I spend too much time doing the analytical physics side, I’m, like, gasping for oxygen.” Research, she said, “is not about drawing within the lines. It’s about discovery and creativity.”

    Quanta Magazine spoke with Sebastian about her research and her unconventional path to science. An edited and condensed version of the interview follows.

    QUANTA MAGAZINE: You search for quantum effects that are entirely new to science. How do you go about looking for them?

    SUCHITRA SEBASTIAN: One option is to look at many, many, many, materials. You can say, “I’m trying to find the one that does something very different.” You may never find it. What I realized is you can use external conditions — pressures or temperatures or magnetic fields — to manipulate a material and move it into a region where it does something really interesting and where new quantum properties emerge.

    Where is that magical region?

    Water can be water, or it can be ice, or it can be steam. These are the same material but in different phases. In the quantum world you can also have different phases. You can have the same material and the same electrons, but the interactions can result either in the substance organizing into one kind of material — so under certain conditions, you can have a magnet — or you exert pressure on the material — you press it — and then it quantum configures in a slightly different way and the magnet transforms into a superconductor. The region I’m excited about is the region between these phases, which is a quantum critical region. Between one phase and another phase you get this intermediate region, where it’s unknown what might happen, and you can have completely new forms of matter emerging.

    What gives rise to the quantum effects?

    Simple materials with weak electron interactions can be modeled just in terms of the electrons’ propensity to hop around, which can be averaged over the entire material. But in more strongly interacting materials, the repulsive force due to interactions between each of the trillions and trillions of electrons is stronger than their propensity to hop around. In this case, the resulting collective effects are almost impossible to predict and can be dramatically different from individual electron behavior.

    Last year, you found an unexpected quantum effect in a material called samarium hexaboride. What was so surprising?

    We think of metals as carrying electricity, and insulators as not. Electrons in metals are traveling long distances, and they’re carrying charge — it’s how electricity flows. In insulators, electrons are largely stuck in one position. That’s why electricity is not being transported in insulators. Samarium hexaboride was predicted to be in a class of materials known as topological insulators, where current flows only on the surface and not in the bulk [the material’s interior].

    We were really, really shocked when the magnetization we measured in the sample started showing wiggles that are characteristic of an electron executing orbits. We see these electrons that travel really long orbits, and they’re coming from the bulk. But the bulk is insulating; those electrons are barely moving. How is it conceivable they’re traveling in these large orbits?

    What might be going on?

    We assume it’s the electrons that are traveling in these orbits, but at the same time, the electrons can’t possibly be moving because there’s no charge moving.

    Maybe what’s happening is that when the electrons come together in this quantum ensemble, we cannot describe the physics in terms of the individual electrons anymore. The possibility is that the electron itself has broken apart. So instead of thinking of the electron as the building block, we would need to think of fractional parts of the electron as building blocks.

    One new finding in support of this is that we do have heat transport through this material, but there are no charges being transported. So maybe you need to think about particles that carry [the quantum property of] spin — which carry heat — and not charge. One possibility is a type of neutral quasiparticle known as a spinon, which carries spin and not charge.

    If it turned out that the electron was no longer the basic building block, that would be very shocking. You can count on the fingers of one hand how many such cases there are.

    Why would it be so shocking?

    It’s always shocking when we discover the fundamental building block of matter isn’t what we thought it was. Originally we thought the fundamental building block was the atom. Then subatomic particles — neutrons, protons and electrons — were discovered.

    When we describe complex materials, we think of the fundamental building block as the electron. One of the overarching quests in condensed matter physics is to find a material that behaves radically differently, as though the electron has broken down, which means we need a new description — not in terms of electronlike quasiparticles but in terms of quasiparticles based on fractional components of an electron.

    One of the clearest examples is the fractional quantum Hall effect, in which instead of an electron that carries charge as the building block, one observes the fundamental building block to be fragments of an electron that carry fractional charges.


    Video: Sebastian talks about how extreme conditions can create unexpected quantum behavior. Philipp Ammon for Quanta Magazine
    Access mp4 video here .

    You have also created a superconductor — a material that transmits electricity without any resistance — by squeezing a magnet with a diamond anvil, a process you call “quantum alchemy.” What strategies do you use to search for new types of superconductors?

    Thus far, if you look at existing superconductors, they’re often close to being magnetic, and they’re often close to being insulating. Another promising feature is layered materials, so that rather than being cubic in their crystal structure, the materials are quite two-dimensional — their crystal structure is stretched out.

    What’s important is to take materials with these promising properties, then apply pressure and go from a non-superconductor into a superconductor. You’re probably not going to start with an optimal high-temperature superconductor by doing this. But if we can make several superconductors from different families of materials, then you’re going to be able to start making a road map: “Now I know these properties of this material gave me a superconductor, but it wasn’t as good as this other one where I started with a material with these other properties.” When you start finding patterns, that will give you a good bridge to then pursue the ultimate optimization of superconductivity.

    What would this optimization lead to, practically?

    One of the big implications of a room-temperature superconductor would be that you could transport energy over very long distances — from anywhere in the world to anywhere else — without any loss. Renewables will be a big part of the future for sustainable energy. What’s not always recognized is that we also need to transport the renewable energy. Solar energy will be abundant in the Sahara, but the most populous cities are, for instance, in New York. How are you going to transport energy over thousands of miles? If you wave a magic wand and get to ideal superconductors, a really long cable would take energy from where it’s created to where it’s most needed. We could start thinking of renewable energy in a more holistic way. You could start thinking more of a worldwide grid.

    Is science doing enough to find more superconductors?

    I don’t think there is a very big effort to search for new superconductors. There are these two questions: How do we understand copper oxide superconductors, which are the one known family of materials that superconduct above liquid-nitrogen temperatures at ambient conditions? And how do we create new superconductors? My impression is about 90 percent of the field’s effort is focused on how to understand copper oxide superconductors. That is a really interesting and important area, but I think there is way too little effort and interest in how to make new superconductors. Personally I feel that scientists should be partnering with industry, or partnering with organizations that are familiar with the idea of assembly-line processes, to accelerate this process of discovery. It’s such an important problem.

    You have some experience working with industry. After studying physics in college, you went on to do an MBA and work as a management consultant for several years before returning to physics. Why did you leave science for a while?

    As much as I love physics and I’m passionate about it, I think the field itself is quite insular, and it does tend to be not very diverse. I didn’t identify with the kind of people I saw doing physics. They didn’t seem very fun or interesting. It seemed like they were really locked into these little worlds, and they knew a lot about what they did, but I felt like they were totally out of touch with the rest of the world. I really need to be engaged with everything around me in different ways. How does the world work, how does economics work, how do governments run? I’m interested in the social implications of what we do. I actually applied to an MBA, I applied to physics, I applied to engineering, and I applied to literature. I interviewed for all of them, and the MBA interview — it was quite an interesting interview. This is how I made my decision.

    But you didn’t enjoy consulting in the end?

    They sell it to you as out-of-the-box thinking and meeting all these interesting people in different fields. But doing it I realized it is not that out-of-the-box thinking. The longer you stay in it, the less it becomes about discovering solutions and the more it becomes about trying to network and market the same old solutions.

    But I will say that I think that is why I recognize how important communication is and how important it is to get your audience on board. I think scientists are sometimes quite complacent in thinking they know a lot about something very specific, and really, if someone doesn’t understand, that’s their problem. But if you’re making a pitch and your client doesn’t buy it, that is your problem. It’s up to you to learn to make a compelling case so you bring people on board. The difference really was, in my consulting work, I wasn’t passionate enough about the solution I was pitching to want to do it the rest of my life. It’s nice, but does it change the world? No. But with physics, I’m passionate about it. It has the potential to revolutionize the world.

    So did you find fulfillment with physics?

    I think it took time to find my own way. I think I needed all those experiences. When I came back to physics, now I’m able to keep all the different parts of me and develop them. Now I can be a more balanced person and recognize that I can do physics without being that stereotypical physicist.

    Physics isn’t just about writing equations on a board and sitting in front of a computer. Science is about exploring new worlds. There are lots of people who would approach the world in that way, but they don’t recognize that physics is about that. We need to attract more of these people to physics.

    You have said, “Who I am is at the heart of the science I do.” Can you explain that?

    I think often people have this impression that the science you do is removed from the person you are. It’s almost like people are swappable. I feel like in physics they don’t really recognize that the person you are is integral to the science you do. The way different people do physics is completely different. I choose to do extremely exploratory physics where I deliberately choose problems where I don’t know what the answer is going to be. But I recognize that for other people, they need to do the kind of physics where you have to be incredibly careful and take years setting something up because you’re looking for the 10th digit to prove a hypothesis. In order to learn more about the world around us, you need to come at it in different ways.

    How have you tried to draw more people to science?

    I’ve done things called soapbox talks before. We go into public spaces — it’s like science busking. It’s literally upturned wooden boxes, and a few people engage with pedestrians walking by, saying, “Do you want to learn about some cool science?” People are really excited about it.

    In your free time, you do theater, and you just spearheaded an art exhibit to celebrate the opening of a new science building at the University of Cambridge. Do you plan to do more art-science events?

    Engaging through the arts is really new for me. But I’m really excited about how well it worked the first time. We are having conversations about taking it forward. Creativity happens when you bring together disparate worlds. If you just do the one thing, and you meet people very similar to you, I think this often reinforces certain ways of thinking and deepens ruts. But where does creativity come from? It comes when you have different approaches intersecting. I think physical spaces are really, really important for this — where people come together, where you have chance encounters. I just really think it’s important to have these interfaces and porous boundaries to break down any kind of siloing.

    See the full article here .

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    Formerly known as Simons Science News, Quanta Magazine is an editorially independent online publication launched by the Simons Foundation to enhance public understanding of science. Why Quanta? Albert Einstein called photons “quanta of light.” Our goal is to “illuminate science.” At Quanta Magazine, scientific accuracy is every bit as important as telling a good story. All of our articles are meticulously researched, reported, edited, copy-edited and fact-checked.

     
  • richardmitnick 3:52 pm on June 9, 2016 Permalink | Reply
    Tags: 2002 image of Cone Nebula, , ,   

    From Hubble: “Hubble’s newest camera images ghostly star-forming pillar of gas and dust” 2002 

    NASA Hubble Banner

    NASA/ESA Hubble Telescope

    NASA/ESA Hubble Telescope

    1

    Resembling a nightmarish beast rearing its head from a crimson sea, this celestial object is actually just a pillar of gas and dust. Called the Cone Nebula (in NGC 2264) – so named because in ground-based images it has a conical shape – this monstrous pillar resides in a turbulent star-forming region. This picture, taken by the newly installed Advanced Camera for Surveys (ACS) aboard the NASA/ESA Hubble Space Telescope, shows the upper 2.5 light-years of the Cone, a height that equals 23 million roundtrips to the Moon. The entire pillar is seven light-years long.

    NASA/ESA Hubble ACS
    NASA/ESA Hubble ACS

    Radiation from hot, young stars (located beyond the top of the image) has slowly eroded the nebula over millions of years. Ultraviolet light heats the edges of the dark cloud, releasing gas into the relatively empty region of surrounding space. There, additional ultraviolet radiation causes the hydrogen gas to glow, which produces the red halo of light seen around the pillar. A similar process occurs on a much smaller scale to gas surrounding a single star, forming the bow-shaped arc seen near the upper left side of the Cone. This arc, seen previously with the Hubble telescope, is 65 times larger than the diameter of our Solar System. The blue-white light from surrounding stars is reflected by dust. Background stars can be seen peeking through the evaporating tendrils of gas, while the turbulent base is pockmarked with stars reddened by dust.

    Over time, only the densest regions of the Cone will be left. But inside these regions, stars and planets may form. The Cone Nebula resides 2500 light-years away in the constellation Monoceros.

    The Cone is a cousin of the M16 pillars, which the Hubble telescope imaged in 1995.

    Pillars of Creation. NASA, ESA, and the Hubble Heritage Team (STScI/AURA)
    Pillars of Creation. NASA, ESA, and the Hubble Heritage Team (STScI/AURA)

    Consisting mainly of cold gas, the pillars in both regions resist being eroded away by the blistering ultraviolet radiation from young, massive stars. Pillars like the Cone and M16 are common in large regions of star birth. Astronomers believe that these pillars may be incubators for developing stars.

    The ACS made this observation on 2 April 2002. The colour image is constructed from three separate images taken in blue, near-infrared, and hydrogen-alpha filters.

    Image credit: NASA, the ACS Science Team (H. Ford, G. Illingworth, M. Clampin, G. Hartig, T. Allen, K. Anderson, F. Bartko, N. Benitez, J. Blakeslee, R. Bouwens, T. Broadhurst, R. Brown, C. Burrows, D. Campbell, E. Cheng, N. Cross, P. Feldman, M. Franx, D. Golimowski, C. Gronwall, R. Kimble, J. Krist, M. Lesser, D. Magee, A. Martel, W. J. McCann, G. Meurer, G. Miley, M. Postman, P. Rosati, M. Sirianni, W. Sparks, P. Sullivan, H. Tran, Z. Tsvetanov, R. White, and R. Woodruff) and ESA

    Credit:
    NASA, Holland Ford (JHU), the ACS Science Team and ESA

    See the full article here .

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

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  • richardmitnick 3:40 pm on June 9, 2016 Permalink | Reply
    Tags: An ancient tale in astronomical time, , , ESO FORS   

    From ESO: “FORS1 at the VLT UT1: First Spectra Obtained” 1998, but too good to pass up 

    ESO 50 Large

    This post is dedicated to the well traveled ESO ambassador O.S. I hope she sees it.

    European Southern Observatory

    7 October 1998 (retrieved from current post http://www.eso.org/public/images/eso9846a/)
    No writer credit in those ancient days

    First commissioning phase successfully completed

    1

    The FORS Team at Paranal has concluded the first phase of the extensive FORS1 commissioning tests at the first 8.2-m VLT Unit Telescope (UT1), successfully and according to the plan. Although this work was primarily aimed at testing the technical performance of this new instrument, it has also been possible to obtain some spectacular images already at this early stage. And now, for the first time, spectra [1] have also been observed with the VLT.

    ESO/FORS1
    ESO/FORS1

    After three weeks of intense work, the FORS team reports that FORS1 has now been trimmed to a very high level of performance. A large amount of test data was obtained in all FORS1 observing modes. They include direct images through various optical filtres of star fields, galactic nebulae, galaxies, galaxy clusters, gravitational arcs as well as spectroscopic and also spectro-polarimetric observations of single and multiple objects. Towards the end, the work concentrated on streamlining certain functions of the control software in order to make observations safe and easy to perform, thereby further optimizing the use of the telescope time.

    The purpose of this Commission Phase 1 was first of all to get the instrument on-line and to prove that all observing modes work correctly. This goal was fully achieved and mostly involved observations of comparatively bright objects although, already now, a spectrum of a 25-magnitude galaxy proved to be no problem. Later, during Commission Phase 2 and especially the subsequent FORS Science Verification programme, observations will also be made of extremely faint objects at the limit of what is possible with FORS1.

    The FORS team is now on its way back to Europe, elated but also quite exhausted after one month of continuous hard work, from the initial installation of the instrument to the final checks during this commissioning phase.

    The following pictures are based on test observations done during the commissioning period now terminated. Full details about the exposures are given below as “Technical Information”.

    The Dumbbell Nebula

    The Dumbbell Nebula – also known as Messier 27 or NGC 6853 – is a typical planetary nebula and is located in the constellation Vulpecula (The Fox). The distance is rather uncertain, but is believed to be around 1200 light-years. It was first described by the French astronomer and comet hunter Charles Messier who found it in 1764 and included it as no. 27 in his famous list of extended sky objects [2].

    Despite its class, the Dumbbell Nebula has nothing to do with planets. It consists of very rarified gas that has been ejected from the hot central star (well visible on this photo), now in one of the last evolutionary stages. The gas atoms in the nebula are excited (heated) by the intense ultraviolet radiation from this star and emit strongly at specific wavelengths.

    2
    eso9846a

    eso9846a is the beautiful by-product of a technical test of some FORS1 narrow-band optical interference filtres. They only allow light in a small wavelength range to pass and are used to isolate emissions from particular atoms and ions.

    3
    eso9846b

    eso9846b is an enlargment that shows well the intricate structure in the central part of the nebula.
    In this three-colour composite, a short exposure was first made through a wide-band filtre registering blue light from the nebula. It was then combined with exposures through two interference filtres in the light of double-ionized oxygen atoms and atomic hydrogen. They were colour-coded as “blue”, “green” and “red”, respectively, and then combined to produce this picture that shows the structure of the nebula in “approximately true” colours.

    4
    eso9846c

    eso9846c shows a direct image of the entire sky field (square and outlined by a blue line) with 19 horizontal strips that define the allowed areas for each of the 19 vertical slits. The positions of the slits that were chosen for this exposure are also indicated by vertical double lines.

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    eso9846d

    eso9846d shows the recorded spectra of the stars in this cluster that were selected for this observation. They appear as bright lines spanning the full field in horizontal direction. Spectrum no. 4 from the top (of star “Be41”) is indicated. The shorter, bright vertical lines are spectral emission lines originating in the terrestrial atmosphere (air glow); they show the extent of the individual slits. Note that in some slits, more than one star spectrum has been registered, thus further increasing the observing efficiency.

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    eso9846e
    FORS1 at the VLT UT1: First Spectra

    Multi-object spectra of extragalactic stars

    One of the main features of the FORS instruments is their ability to do multi-object spectroscopy (MOS), i.e., to obtain spectra of several objects at the same time. Many conventional spectrographs in use at telescopes around the world are only capable of observing one spectrum at a time. This necessitates a large amount of precious observing time when spectra of several stars or galaxies shall be observed, e.g., for comparison, or when searching for objets with unusual physical properties.

    FORS1 and FORS2 are designed in such a way that they can register spectra of up to 19 astronomical objects simultaneously. Moreover, they can change from one set of objects to the next within seconds. This greatly increases the observing efficiency and ensures that valuable data can be obtained much faster. That is particularly useful during especially excellent, but relatively rare observing conditions.

    The MOS mode of FORS1 is here illustrated by example of spectra of stars in the open cluster NGC 330 in the Small Magellanic Cloud (SMC)[No illustration present]. The SMC is a companion galaxy of our Milky Way galaxy at a distance of about 150,000 light-years. It is seen deep down in the southern sky and will be a main object of future studies with the VLT.

    Small Magellanic Cloud. NASA/ESA Hubble and ESO/Digitized Sky Survey 2
    Small Magellanic Cloud. NASA/ESA Hubble and ESO/Digitized Sky Survey 2

    Sophisticated software was written by the FORS consortium that allows interactive allocation of target objects in the sky field to the individual slits of the multi-object spectroscopy unit (MOS) of FORS1. The dispersing element that separates the incoming light into different wavelengths (colours) is a grism (a glass prism with a ruled grating replicated onto a thin resin layer on one of the prism surfaces). FORS1 has different grisms that produce spectra with different spectral resolutions. This allows a wide range of projects to be carried out, from quite detailed spectra of brighter objects, to low-resolution spectra of very faint objects, e.g., extremely distant galaxies.

    The FORS1 MOS spectrum was taken for technical reasons, in order to verify the accuracy with which the positions of the individual MOS slits can be set. Therefore, fairly bright stellar objects (down to about 19th magnitude) and a comparatively short exposure time were used. However, already on such “technical” spectra, it will be possible to perform very useful science, as explained below.

    NGC 330 is an extraordinary, young open star cluster. It is famous because it is extremely metal poor, even more than its surroundings in the Small Magellanic Cloud. It furthermore contains unusually many Be stars . In fact, no less than about 70% of its B stars belong to this peculiar variety, compared to about 10% in star clusters of our own Milky Way Galaxy. Be stars are fairly young and hot (~30,000 K) and rotate comparatively fast. Their spectra show broad emission lines of hydrogen from a rotating circumstellar disk. The reason for the overabundance of Be stars in NGC 330 is not known with certainty; the reason may be the very low content of heavy elements.

    Until now, the fainter Be stars in NGC 330 have only been identified by means of photometric observations of their colours. Now, however, the FORS Team was able to obtain the first spectra of some of these stars and confirm the presence of emission lines. eso9846e displays the tracing (brightness vrs. wavelength) of the spectrum of star “Be41” in NGC 330. It is of magnitude 17 and the spectrum isa the fourth from the top in eso9846d. In addition to broad absorption lines of hydrogen and helium (a doppler effect of the rapid rotation), there is a sharp H-beta emission peak from hydrogen near the center of the spectrum, thus confirming it as a Be star . Note that this emission line can also be seen as a bright spot in spectrum no. 4 in eso9846d.
    Notes

    [1] A spectrum is the dispersion of light from an object into the colours of the rainbow. Spectroscopy is a key technique in astronomy: From a spectrum, it is possible to deduce important information about the object emitting the light, e.g. its chemical composition, surface temperature and the direction and speed of its motion (relative to us). This is especially important in the investigation of very distant objects as it allows the determination of their distance due to the expansion of the universe. This will be one of the main domains of the work with FORS.

    [2] More information about this impressive object is available on the web at various locations, e.g., http://messier.seds.org/m/m027.html.

    See the full article here .

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