A Galactic Self-portrait: Density Structure and Integrated Properties of the Milky Way Disk

作者：Julie Imig, Jon A. Holtzman, Gail Zasowski, Jianhui Lian, Nicholas Fraser Boardman, Alexander Stone-Martinez, J. Ted Mackereth, Moire K. M. Prescott, Rachael L. Beaton, Timothy C. Beers, Dmitry Bizyaev, Michael R. Blanton, Kátia Cunha, José G. Fernández-Trincado, Catherine E. Fielder, Sten Hasselquist, Christian R. Hayes, M. Haywood, Henrik Jönsson, Richard R. Lane, Steven R. Majewski, Szabolcs Mészáros, Ivan Minchev, David L. Nidever, Christian Nıtschelm, Jennifer Sobeck · 发表于：The Astrophysical Journal · 年份：2025 · DOI：10.3847/1538-4357/adf723 · 被引用次数：6 · 研究领域：Stellar, planetary, and galactic studies、Astrophysics and Star Formation Studies、Astronomy and Astrophysical Research

Abstract The evolutionary history of the Milky Way disk is imprinted in the ages, positions, and chemical compositions of individual stars. In this study, we derive the intrinsic density distribution of different stellar populations using the final data release of the Apache Point Observatory Galactic Evolution Experiment (APOGEE) survey. A total of 203,197 red giant branch stars are used to sort the stellar disk ( R ≤ 20 kpc) into subpopulations of metallicity (Δ[M/H] = 0.1 dex), age ( Δ log ( age yr ) = 0.1 ), and α -element abundances ([ α /M]). We fit the present-day structural parameters and density distribution of each stellar subpopulation after correcting for the survey selection function. The low- α disk is characterized by longer scale lengths and shorter scale heights, and is best fit by a broken exponential radial profile for each population. The high- α disk is characterized by shorter scale lengths and larger scale heights, and is generally well-approximated by a single exponential radial profile. These results are applied to produce new estimates of the integrated properties of the Milky Way from early times to the present day. We measure the total stellar mass of the disk to be 5.2 7 − 1.5 + 0.2 × 1 0 10 M ⊙ , and the average mass-weighted scale length is R d = 2.37 ± 0.2 kpc. The Milky Way’s present-day color of ( g − r ) = 0.72 ± 0.02 is consistent with the classification...