Galactic Rotation and Solar Motion from Stellar Kinematics

Understand

I present three methods to determine the distance to the Galactic centre R0, the solar azimuthal velocity in the Galactic rest frame Vg,\odot and hence the local circular speed Vc at R0.

• These simple, model-independent strategies reduce the set of assumptions to near axisymmetry of the disc and are designed for kinematically hot stars, which are less affected by spiral arms and other effects.
• The first two methods use the position-dependent rotational streaming in the heliocentric radial velocities U.
• The resulting rotation estimate {\theta} from U velocities does not depend on Vg,\odot.