2026/04/27 by Wenbo Wu, Yuqin Chen, Jianhui Lian +10 · 1 voice
#astro-ph.GA
paper · pdf · doi:10.3847/1538-4357/ae5236
This study explores the density profile of the stellar disk, radially and azimuthally, based on approximately 8.4 million red clump stars selected from Gaia Bp/Rp spectra. After correcting for selection effects and distance uncertainties, we fit the vertical stellar density profile of the Galactic disk with a two-component model consisting of geometrically thin and thick disks. Our derived density profile shows several breaks radially: (1) a steep exponential inside R∼3 kpc; (2) a nearly flat plateau from R∼3 to ∼7 kpc; (3) an exponential decline beyond the solar radius to around 13 kpc; (4) a sharper exponential drop-off beyond R∼13 kpc. The parameters of these four main components depend on φ to some extent. Variation of the termination radius of the first component suggests an interaction with the bar/bulge. Besides the typical flaring at R>6.4 kpc, we find that the thin disk also exhibits a similar and smooth thickening/flaring feature toward the Galactic center at R<6.4 kpc. The observed inner flaring may indicate heating effects introduced by the Galactic bar, since R=6.4 kpc lies close to the co-rotation radius where the bar's dynamical influence becomes significant. Additionally, we identify a localized density bump in the region 5<R<7 kpc and -30^∘<φ<15^∘, where a corresponding metallicity bump is also visible near the Galactic plane. This density/metallicity bump may be related to the recently reported bimodal distribution of the guiding radius of super metal-rich stars in the solar vicinity through radial migration.