Astronomy and Astrophysics – Astronomy
Scientific paper
Jan 2011
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2011aas...21725008b&link_type=abstract
American Astronomical Society, AAS Meeting #217, #250.08; Bulletin of the American Astronomical Society, Vol. 43, 2011
Astronomy and Astrophysics
Astronomy
Scientific paper
We use SDSS photometry for 73 million stars to simultaneously obtain best-fit main-sequence stellar energy distribution and the amount of dust extinction along the line of sight towards each star. Using a subsample of 23 million stars with 2MASS photometry, whose addition enables more robust results, we show that SDSS photometry alone is sufficient to break degeneracies between intrinsic stellar color, dust amount, and dust properties. 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 degrees). Our results are in good agreement with the extinction normalization given by the Schlegel, Finkbeiner & Davis (1998, 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. For the latter, we find a ratio of the total to selective absorption to be RV = 3.01 ± 0.05(random)±0.1 (systematic) over most of the high-latitude sky. At low galactic latitudes (|b| < 5 degrees), 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 present evidence that sometimes the SFD map grossly overestimates the dust extinction at low galactic latitudes even when these distance effects are accounted for. In cases where such discrepancies are large, they seem correlated with the distribution of molecular gas. We analyze three-dimensional maps of the best-fit RV and show that it can reach values as high as 5-6 in some low-latitude regions with large amounts of dust.
Berry Michael
Ivezic Zeljko
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