The Three-Dimensional Density Distribution of Candidate AGB Stars in the Milky Way
Abstract
We study the structure of the Milky Way disk candidate asymptotic giant branch (AGB) stars selected from the infrared ALLWISE catalog. The advantages of our approach, compared to most recent similar works such as those based on SDSS data, are large distance limits due to the high luminosity of AGB stars, small interstellar dust obscuration due to longer wavelengths, and the all-sky coverage of the WISE survey. The candidate AGB stars are color-selected with high completeness and low contamination, as quantified using samples of known AGB stars and other objects with known classifications from the SIMBAD and SDSS databases. Distances to candidate AGB stars are estimated simultaneously with interstellar dust extinction along the line of sight using a 3-dimensional dust distribution model developed to support LSST simulations and a color vs. absolute magnitude relation calibrated using the LMC and the Galactic bulge. We find that the Galactic disk extends radially out to about 15 kpc, and that it is flaring towards its edge. We present measurements of the vertical scale height and scale length for double-exponential disk models. We find that the density distribution of AGB candidates within 9 kpc from the Galactic center is consistent with that of a double-exponential profile, while at larger radii the distribution is indistinguishable from a single-exponential profile.
- Publication:
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American Astronomical Society Meeting Abstracts #225
- Pub Date:
- January 2015
- Bibcode:
- 2015AAS...22514220H