THE MILKY WAY TOMOGRAPHY WITH SLOAN DIGITAL SKY SURVEY. IV. DISSECTING DUST

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