The RAVE stellar velocity gradient in the extended solar neighbourhood

Benoit Famaey

University of Strasbourg

Moving groups such as the Hyades and Sirius streams, containing stars of very different ages and chemical compositions, were until recently the best local dynamical tracers of the bar and spiral of the Milky Way. These dynamical tracers are also complemented by the observed non-zero value of the Oort constant C as determined from proper motion surveys of red giants in the extended local disk. Here, we additionally report the recent detection of a radial velocity gradient in the inner disk, with RAVE line-of-sight velocities of more than 200 thousand stars limited to a distance of 2 kpc from the Sun. Further observational confirmation of this finding, e.g. with line-of-sight velocities of stars at lower latitudes and to larger distances, together with further modeling, should help better constrain the radial motion of the Local Standard of Rest, as well as the non-axisymmetric components of the Galactic potential and their ability at radially mixing the stellar disk.