A three-dimensional extinction map of the Galactic anticentre from multiband photometry

Abstract

We present a three dimensional extinction map in r band. The map has a spatial angular resolution, depending on latitude, between 3 -9 arcmin and covers the entire XSTPS-GAC survey area of over 6,000 deg 2 for Galactic longitude 140 ď l ď 220 deg and latitude´40 ď b ď 40 deg. By cross-matching the photometric catalog of the Xuyi Schmidt Telescope Photometric Survey of the Galactic Anticentre (XSTPS-GAC) with those of 2MASS and WISE, we have built a multi-band photometric stellar sample of about 30 million stars and applied spectral energy distribution (SED) fitting to the sample. By combining photometric data from the optical to the near-infrared, we are able to break the degeneracy between the intrinsic stellar colours and the amounts of extinction by dust grains for stars with high photometric accuracy, and trace the extinction as a function of distance for low Galactic latitude and thus highly extincted regions. This has allowed us to derive the best-fit extinction and distance information of more than 13 million stars, which are used to construct the three dimensional extinction map. We have also applied a Rayleigh-Jeans colour excess (RJCE) method to the data using the 2MASS and WISE colour pH´W2q. The resulting RJCE extinction map is consistent with the integrated two dimensional map deduced using the best-fit SED algorithm. However for individual stars, the amounts of extinction yielded by the RJCE method suffer from larger errors than those given by the best-fit SED algorithm.

LAMOST Spectroscopic Survey of the Galactic Anticentre (LSS-GAC): target selection and the first release of value-added catalogues

“…28. Note that within the footprint of LSS-GAC, stars in the southern Galactic hemisphere overall suffer from higher extinction than those in the north (Chen et al 2014). As a consequence, most control sample stars are from the northern hemisphere.…”

“…Given that the stellar colour loci for main sequence stars are well described by a single parameter, i.e., the effective temperature, reddening can also be determined from multi-band photometry alone by fitting the stellar SED from the optical to the near-IR (e.g., Berry et al 2012). Using this technique and combining the photometry of XSTPS-GAC in the optical, 2MASS and WISE in the near to mid-IR, Chen et al (2014) has derived values of extinction and distances for about 15 million stars surveyed by the XSTPS-GAC, including most stars targeted by the LSS-GAC.…”

“…Values of E(B −V ) phot are systematically smaller than those of E(B − V )sp by about 0.06 mag. The differences are possibly caused by the spatial variations of the extinction law as well as by the uncertainties of the photometric method which tends to underestimate the true values of reddening (Chen et al 2014).…”

“…ebv sfd E(B − V ) from the SFD extinction map (mag) 61 ebv sp E(B − V ) derived from the star pair method (mag) 62 ebv mod E(B − V ) derived by comparing the observed and synthetic model atmosphere colours (mag) 63 ebv phot E(B − V ) derived by fitting multi-band photometry to the empirical stellar loci (Chen et al 2014 Three samples consisting of stars of spectral S/N(4650Å) 10 are defined, corresponding to, respectively, the footprints of the LSS-GAC main, M31-M33 and VB surveys. Spectral classifications and stellar parameters yielded by the LSP3 are presented in publically accessible online valueadded catalogues, supplementary to the official LAMOST DR1.…”

Three-Dimensional Dust Mapping Reveals That Orion Forms Part of a Large Ring of Dust

“…We use the technique of Green et al (2014), taking advantage of high-quality optical photometry from Pan-STARRS1 to find the distances and reddenings to stars. This effort is related to that of Lallement et al (2014), , Chen et al (2014), Hanson & Bailer-Jones (2014), and Marshall et al (2006), who also map the Galaxy's dust in three dimensions. The work of Schlafly et al (2014b) and Schlafly et al (2014a) has recently used data from Pan-STARRS1 to create a catalog of distances to major dust clouds and to map the angular structure of the dust, demonstrating the value of this technique.…”