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The Milky Way Tomography with Sloan Digital Sky Survey. IV. Dissecting Dust

Berry, Michael and Sesar, Branimir (2012) The Milky Way Tomography with Sloan Digital Sky Survey. IV. Dissecting Dust. Astrophysical Journal, 757 (2). Art. No. 166. ISSN 0004-637X.

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We use Sloan Digital Sky Survey (SDSS) photometry of 73 million stars to simultaneously constrain best-fit main-sequence stellar spectral energy distribution (SED) and amount of dust extinction along the line of sight toward each star. Using a subsample of 23 million stars with Two Micron All Sky Survey (2MASS) photometry, whose addition enables more robust results, we show that SDSS photometry alone is sufficient to break degeneracies between intrinsic stellar color and dust amount when the shape of extinction curve is fixed. When using both SDSS and 2MASS photometry, the ratio of the total to selective absorption, R_V , can be determined with an uncertainty of about 0.1 for most stars in high-extinction regions. These fits enable detailed studies of the dust properties and its spatial distribution, and of the stellar spatial distribution at low Galactic latitudes (|b| < 30°). Our results are in good agreement with the extinction normalization given by the Schlegel et al. (SFD) dust maps at high northern Galactic latitudes, but indicate that the SFD extinction map appears to be consistently overestimated by about 20% in the southern sky, in agreement with recent study by Schlafly et al. The constraints on the shape of the dust extinction curve across the SDSS and 2MASS bandpasses disfavor the reddening law of O'Donnell, but support the models by Fitzpatrick and Cardelli et al. For the latter, we find a ratio of the total to selective absorption to be RV = 3.0 ± 0.1(random)±0.1 (systematic) over most of the high-latitude sky. At low Galactic latitudes (|b| < 5°), we demonstrate that the SFD map cannot be reliably used to correct for extinction because most stars are embedded in dust, rather than behind it, as is the case at high Galactic latitudes. We analyze three-dimensional maps of the best-fit R_V and find that R_V = 3.1 cannot be ruled out in any of the 10 SEGUE stripes at a precision level of ~0.1-0.2. Our best estimate for the intrinsic scatter of R_V in the regions probed by SEGUE stripes is ~0.2. We introduce a method for efficient selection of candidate red giant stars in the disk, dubbed "dusty parallax relation," which utilizes a correlation between distance and the extinction along the line of sight. We make these best-fit parameters, as well as all the input SDSS and 2MASS data, publicly available in a user-friendly format. These data can be used for studies of stellar number density distribution, the distribution of dust properties, for selecting sources whose SED differs from SEDs for high-latitude main-sequence stars, and for estimating distances to dust clouds and, in turn, to molecular gas clouds.

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Sesar, Branimir0000-0002-0834-3978
Additional Information:© 2012 American Astronomical Society. Received 2011 November 18; accepted 2012 July 1; published 2012 September 14. Z. Ivezić and B. Sesar acknowledge support by NSF grants AST-615991 and AST-0707901, and by NSF grant AST-0551161 to LSST for design and development activity. Ž. Ivezić thanks the University of Zagreb, where a portion of this work was completed, for its hospitality, and acknowledges support by the Croatian National Science Foundation grant O-1548-2009. M. Berry, Ž. Ivezić, and B. Sesar acknowledge hospitality by the Institute for Astronomy, University of Hawaii. D. Finkbeiner and E. Schlafly acknowledge the support of NASA grant NNX10AD69G. This work was supported by the Director, Office of Science, Office of High Energy Physics, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. T. C. Beers acknowledges partial support from PHY 08-22648: Physics Frontier Center/Joint Institute for Nuclear Astrophysics (JINA), awarded by the U.S. National Science Foundation. We acknowledge the hospitality of the KITP at the University of California, Santa Barbara, where part of this work was completed (supported by NSF grant PHY05-51164). Fermilab is operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy. Funding for the SDSS and SDSS-II has been provided by the Alfred P. Sloan Foundation, the Participating Institutions, the National Science Foundation, the U.S. Department of Energy, the National Aeronautics and Space Administration, the Japanese Monbukagakusho, the Max Planck Society, and the Higher Education Funding Council for England. The SDSS Web site is The SDSS is managed by the Astrophysical Research Consortium for the Participating Institutions. The Participating Institutions are the American Museum of Natural History, Astrophysical Institute Potsdam, University of Basel, University of Cambridge, Case Western Reserve University, University of Chicago, Drexel University, Fermilab, the Institute for Advanced Study, the Japan Participation Group, Johns Hopkins University, the Joint Institute for Nuclear Astrophysics, the Kavli Institute for Particle Astrophysics and Cosmology, the Korean Scientist Group, the Chinese Academy of Sciences (LAMOST), Los Alamos National Laboratory, the Max-Planck-Institute for Astronomy (MPIA), the Max-Planck- Institute for Astrophysics (MPA), New Mexico State University, Ohio State University, University of Pittsburgh, University of Portsmouth, Princeton University, the United States Naval Observatory, and the University of Washington.
Funding AgencyGrant Number
Croatian National Science FoundationO-1548-2009
Department of Energy (DOE)DE-AC02-05CH11231
NSFPHY 08-22648
Subject Keywords:catalogs; dust, extinction; stars: statistics; surveys
Issue or Number:2
Record Number:CaltechAUTHORS:20121106-153920625
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Official Citation:The Milky Way Tomography with Sloan Digital Sky Survey. IV. Dissecting Dust Michael Berry et al. 2012 ApJ 757 166
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:35315
Deposited By: Jason Perez
Deposited On:07 Nov 2012 00:22
Last Modified:03 Oct 2019 04:27

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