Galaxy: kinematics and dynamics

The surface mass density of the Milky Way: does the traditional $K_Z$ approach work in the context of new surveys?

Abstract We revisit the classical $K_Z$ problem — determination of the vertical force and implied total mass density distribution of the Milky Way disk — for a wide range of Galactocentric radius and vertical height using chemically selected thin and thick disk samples based on APOGEE spectroscopy combined with the Gaia astrometry. We derived the velocity dispersion profiles in Galactic cylindrical coordinates, and solved the Jeans Equation for the two samples separately.

Ripple Patterns in In-plane Velocities of OB Stars from LAMOST and Gaia

Abstract With about 12,000 OB type stars selected from the LAMOST and Gaia survey, we study their 3 dimensional velocity distribution over the range of galactocentric radius from 6 to 15 kpc in the Galactic disk plane. A clear ripple pattern in the radial velocity ($V_R$) map is shown. The median $V_R$ reaches $-8$ km s$^{-1}$ at $R\sim9$ kpc, then increases to $\sim0$ km s$^{-1}$ at $R\sim12$ kpc, and later declines to below $-10$ km s$^{-1}$ beyond $R\sim13$,kpc.