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Penn State Joins New Project to Map the Universe

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12 August 2014
Click on the Image for a high-resolution version. Schneider_MaNGA_7-2014.jpgThe new SDSS will measure spectra at multiple points in the same galaxy, using a newly created fiber bundle technology. The left-hand side shows the Sloan Foundation Telescope and a close-up of the tip of the fiber bundle. The bottom right illustrates how each fiber will observe a different section of each galaxy. The image (from the Hubble Space Telescope) shows one of the first galaxies that the new SDSS has measured. The top right shows data gathered by two fibers observing two different part of the galaxy, showing how the spectrum of the central regions differs dramatically from outer regions. Credit: Dana Berry / SkyWorks Digital, Inc., David Law, SDSS Collaboration Hubble Space Telescope image credit: NASA, ESA, the Hubble Heritage (STScI/AURA)-ESA/Hubble Collaboration, and A. Evans (University of Virginia, Charlottesville/NRAO/Stony Brook University)

Penn State is an institutional partner in a major new research effort to investigate the structure of our galaxy, the evolution of nearby galaxies, and the nature of dark energy. The effort is the newest phase of the Sloan Digital Sky Survey (SDSS-IV), an international collaboration of more than 200 astronomers at over 40 institutions. "The SDSS has been one of the most productive endeavors in the history of astronomy, and it provides exciting scientific opportunities to Penn State faculty and students," remarked Donald Schneider, the head of the Penn State's Department of Astronomy and Astrophysics.

Changing a cartridge, opening the enclosure, sunset, and nightly observing at the Sloan Foundation 2.5m Telescope at Apache Point Observatory, Sunspot, New Mexico. During the night, an observer changes the cartridge to observe a new set of stars or galaxies roughly every hour. Each cartridge contains hundreds of fiber-optic cables plugged into holes in a large aluminum plate. Each fiber observes a single star or galaxy. The "bright time" observing is during a nearly full moon, the "dark time" is before moonrise, with the moon (not the sun!) rising shortly before the end of the video. The orange glow in the background is from the city of El Paso, Texas, 90 miles to the south. The multi-colored lights briefly shining through the telescope petals before and after cartridge changes are calibration sequences. We use different light sources to check that all parts of the instrument see light the same way and to compare the observations to known standards. Credit: Music from "Just Ancient Loops" Composed by Michael Harrison, Cellos performed by Maya Beiser From the Cantaloupe Music CD Time Loops.  Video: Sloan Digital Sky Survey

The SDSS-IV survey has three primary scientific programs. The first is to explore the compositions and motions of stars across the entire Milky Way in unprecedented detail. SDSS-IV will use an instrument that is sensitive to infrared light to peer through the dust in our galaxy to investigate the properties of over 100,000 stars in our own galaxy. "The unique capabilities of the infrared instrument will help us to understand the dynamics and compositions of stellar populations in our galaxy, binary stars, and the properties of planet-hosting stars discovered by the Kepler mission," said Assistant Professor of Astronomy and Astrophysics Suvrath Mahadevan.

In addition to the Sloan Foundation's 2.5-meter Telescope in New Mexico, SDSS-IV will obtain observations with the 2.5-meter Irinie du Pont Telescope at Las Campanas Observatory, high in the Chilean Andes, where the skies are among the clearest on Earth. The Chilean telescope will allow a full study of the Milky Way, reaching areas of the sky that are inaccessible from New Mexico. It also will be used to investigate of the Magellanic Clouds -- nearby dwarf galaxies that are always below the horizon in New Mexico.

Click on the image for a high-resolution version. Schneider_APOGEE_7-2014.jpgSDSS-IV will extend its reach by using both the Sloan Foundation Telescope at Apache Point Observatory and the du Pont telescope at Las Campanas Observatory in Chile, as shown on the left. Because of the orientation of the Earth’s axis relative to the disk of the Milky Way, the northern telescope will observe a very different part of the Milky Way (shaded in blue) than the southern telescope (shaded in green), which will have an excellent view of the galactic center regions. The nested spheres show the range of distances from the Sun that the survey of the Milky Way will reach, depending on survey strategy and the density of stars and dust along the line-of-sight. Some observations will reach to the innermost sphere, while the deepest observations will extend to the outermost sphere and our neighboring dwarf galaxies, the Magellanic Clouds, shown at the bottom of the image. Credit: Dana Berry / SkyWorks Digital, Inc. and the SDSS collaboration

The second program of SDSS-IV also will improve our understanding of the large-scale structure of the universe. The survey will accurately measure the expansion history of the universe through 80 percent of cosmic history, back to times when the universe was less than three billion years old. These detailed measurements will improve constraints on the nature of dark energy, the most mysterious experimental result in modern physics.

"These observations of distant objects also will extend greatly our ability to monitor the variations of the emission from quasars, providing insights into how quasar winds, which have speeds of millions of miles per hour, are created," remarked Niel Brandt, distinguished professor of Astronomy and Astrophysics at Penn State. "These violent motions, ultimately powered by material falling into supermassive black holes, are crucial to our understanding of the growth of black holes and the evolution of their host galaxies."

Click on the image for a high-resolution version.
 Schneider_eBOSS_7-2014.jpgPreviously, SDSS has mapped the universe across billions of light-years, focusing on the time from 7 billion years after the Big Bang to the present and the time from 2 billion years to 3 billion years after the Big Bang. SDSS-IV will focus on mapping the distribution of galaxies and quasars 3 billion years to 7 billion years after the Big Bang, a critical time when dark energy is thought to have started to affect the expansion of the Universe.
Credit: Dana Berry / SkyWorks Digital, Inc. and SDSS collaboration and WMAP cosmic microwave background image credit: NASA/WMAP Science Team

SDSS-IV will use innovative new technology to produce detailed maps of thousands of nearby galaxies. Construction of these maps now is made possible with a new technique for bundling sets of fiber-optic cables into tightly-packed arrays. These fiber arrays collect light from across the entire extent of a galaxy, enabling detailed spectral measurements during the duration of the SDSS-IV project of more than 10,000 nearby galaxies. "Our goal is to understand the 'life cycle' of present-day galaxies from imprinted clues of their birth and assembly, through their ongoing growth via star formation and merging, to their eventual fade-out after star formation ends," said Matt Bershady of the University of Wisconsin, the SDSS-IV Project Scientist.

With the enhanced capabilities of its powerful instruments, a new outpost in the Southern Hemisphere, and the continuing generous support of the Alfred P. Sloan Foundation, the SDSS continues to be one of the world's most productive astronomical facilities. Penn State astronomers, and others worldwide, anticipate that science results from the SDSS will continue to reshape our view of the fundamental constituents of the cosmos, the universe of galaxies, and our home in the Milky Way.


[ D P S / B K K ]


Penn State SDSS Contacts:


Penn State Public Information Officer:


SDSS Director:


SDSS Spokesperson:


SDSS Press Officer:

  • Jordan Raddick, SDSS-IV Public Information Officer, Johns Hopkins University, raddick@jhu.edu, 1-410-516-8889



Funding for the Sloan Digital Sky Survey IV has been provided by the Alfred P. Sloan Foundation and the Participating Institutions. SDSS-IV acknowledges support and resources from the Center for High-Performance Computing at the University of Utah. The SDSS web site is www.sdss.org.

SDSS-IV is managed by the Astrophysical Research Consortium for the Participating Institutions of the SDSS Collaboration including the Carnegie Institution for Science, Carnegie Mellon University, the Chilean Participation Group, Harvard-Smithsonian Center for Astrophysics, Instituto de Astrofisica de Canarias, The Johns Hopkins University, Kavli Institute for the Physics and Mathematics of the Universe (IPMU)/University of Tokyo, Lawrence Berkeley National Laboratory, Leibniz Institut fur Astrophysik Potsdam (AIP), Max-Planck-Institut fur Astrophysik (MPA Garching), Max-Planck-Institut fur Extraterrestrische Physik (MPE), Max-Planck-Institut fur Astronomie (MPIA Heidelberg), National Astronomical Observatory of China, New Mexico State University, New York University, The Ohio State University, Penn State University, Shanghai Astronomical Observatory, United Kingdom Participation Group, Universidad Nacional Autonoma de Mexico, University of Arizona, University of Colorado Boulder, University of Portsmouth, University of Utah, University of Washington, University of Wisconsin, Vanderbilt University, and Yale University.

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