Three-Dimensional Reddening Map for Stars from 2MASS Photometry: The Method and the First Results

Abstract

The first results of the construction of a 3D reddening map for stars within 1600 pc of the Sun are presented. Analysis of the distribution of 70 million stars from the 2MASS catalog with the most accurate photometry on the (J-Ks) - Ks diagram supplemented with Monte Carlo simulations has shown that one of the maxima of this distribution corresponds to F-type dwarfs and subgiants with a mean absolute magnitude MKs=2.5m. The shift of this maximum toward large (J-Ks) with increasing $Ks$ reflects the reddening of these stars with increasing heliocentric distance. The distribution of the sample of stars over Ks, l, and b cells with corresponds to their distribution over 3D spatial cells. As a result, the reddening E(J-Ks) has been determined with an accuracy of 0.03m for spatial cells with a side of 100 pc. All of the known large absorbing clouds within 1600 pc of the Sun have manifested themselves in the results obtained. The distances to the near and far edges of the clouds have been determined with a relative accuracy of 15\%. The cases where unknown clouds are hidden behind known ones on the same line of sight have been found. The distance dependence of reddening is considered for various Galactic latitudes and longitudes. The absorbing matter of the Gould Belt is shown to manifest itself at latitudes up to 40 deg and within 600 pc of the Sun. The size and influence of the Gould Belt may have been underestimated thus far. The absorbing matter at latitudes up to 60 deg and within 1600 pc of the Sun has been found to be distributed predominantly in the first and second quadrants in S hemisphere and in the third and fourth quadrants in N hemisphere. A nonrandom orientation of the clouds relative to the Sun is possible. The mass of the baryonic dark matter in solar neighborhoods can then be considerably larger than is generally believed.