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  • richardmitnick 5:21 pm on March 22, 2017 Permalink | Reply
    Tags: 2MASS, , , , , , , Dark Energy Spectroscopic Instrument (DESI), , , New Study Maps Space Dust in 3-D, ,   

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

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    Berkeley Lab

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


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

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

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

    Building a better dust map

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

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

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

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

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

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

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

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

    Combined data from sky surveys shed new light on dust

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

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

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

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

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

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


    SDSS Telescope at Apache Point Observatory, NM, USA

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

    New questions emerge on the makeup of space dust

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

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

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

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


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

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

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

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

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

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

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

    See the full article here .

    Please help promote STEM in your local schools.

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    A U.S. Department of Energy National Laboratory Operated by the University of California

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  • richardmitnick 9:47 am on April 17, 2016 Permalink | Reply
    Tags: 2MASS, , , ,   

    From JPL-Caltech: “A Space Spider Watches Over Young Stars” 

    NASA JPL Banner

    JPL-Caltech

    1

    The spider part of The Spider and the Fly” nebulae, IC 417 abounds in star formation, as seen in this infrared image from NASA’s Spitzer Space Telescope and the Two Micron All Sky Survey (2MASS).

    NASA/Spitzer Telescope
    NASA/Spitzer Telescope

    Caltech 2MASS Telescope
    Caltech 2MASS telescope interior
    Caltech 2MASS Telescope

    Located in the constellation Auriga, IC 417 lies about 10,000 light-years away. It is in the outer part of the Milky Way, almost exactly in the opposite direction from the galactic center. This region was chosen as the subject of a research project by a group of students, teachers and scientists as part of the NASA/IPAC Teacher Archive Research Program (NITARP) in 2015.

    A cluster of young stars called “Stock 8” can be seen at center right. The light from this cluster carves out a bowl in the nearby dust clouds, seen here as green fluff. Along the sinuous tail in the center and to the left, groupings of red point sources are also young stars.

    In this image, infrared wavelengths, which are invisible to the unaided eye, have been assigned visible colors. Light with a wavelength of 1.2 microns, detected by Caltech 2MASS Telescope, is shown in blue. The Spitzer wavelengths of 3.6 and 4.5 microns are green and red, respectively.

    Spitzer data used to create this image were obtained during the space telescope’s “warm mission” phase, following its depletion of coolant in mid-2009. Due to its design, Spitzer remains cold enough to operate efficiently at two channels of infrared light. It is now in its 12th year of operation since launch.

    The 2MASS mission was a joint effort between the California Institute of Technology, Pasadena; the University of Massachusetts, Amherst; and NASA’s Jet Propulsion Laboratory, Pasadena, California.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    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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