Determination of the Solar Galactocentric Distance from the Kinematics of Masers

Abstract

We determine the parameters of Galactic rotation and the solar galactocentric distance R0 by simultaneously solving Bottlinger’s kinematic equations using data for masers with known line-of-sight velocities and highly accurate VLBI trigonometric parallaxes and proper motions. Our sample includes 93 masers spanning the range of galactocentric distances R from 3 to 15 kpc. The inferred parameters are Ω0 = 29.7 ± 0.5 km s−1 kpc−1, Ω′0 = −4.20 ± 0.11 km s−1 kpc−2, Ω″0 = 0.730 ± 0.029 km s−1 kpc−3, and R0 = 8.03 ± 0.12 kpc, implying a circular rotation velocity of V0 = 238 ± 6 km s−1 at the solar distance R0.

Keywords

• masers
• galaxy: kinematics and dynamics
• galaxy: solar galactocentric distance