Parameters of the Galactic rotation curve and spiral pattern from Cepheid kinematics

Abstract

A method is developed for analyzing stellar velocity fields in our Galaxy, with allowance for spiral-density-wave perturbations. The parameters of the Galactic rotation curve, spiral pattern, and mean solar motion are inferred using new Cepheid radial velocities and proper motions measured by the HIPPARCOS space telescope. The Sun is very close to the corotation circle, where the velocity of the Galactic rotation coincides with the velocity of the spiral pattern: the corotation radius is R_C ~ 7.3 kpc, whereas the radius of the solar circle is R_solar ~ 7.5 kpc.