Radial distribution of stellar motions inGaiaDR2

Abstract

By taking advantage of the superb measurements of position and velocity for an unprecedented large number of stars provided inGaiaDR2, we have generated the first maps of the rotation velocity,Vrot, and vertical velocity,Vz, distributions as a function of the Galactocentric radius, Rgal, across a radial range of 5 < Rgal < 12 kpc. In theR-Vrot map, we have identified many diagonal ridge features, which are compared with the location of the spiral arms and the expected outer Lindblad resonance of the Galactic bar. We have detected also radial wave-like oscillations of the peak of the vertical velocity distribution.