Study of the Galactic Rotation Based on Masers and Radio Stars with VLBI Measurements of Their Parallaxes

Abstract

Based on published data, we have produced a sample of 256 radio sources whose trigonometric parallaxes and proper motions were measured by VLBI. This sample contains Galactic masers associated with massive protostars and stars in active star-forming regions. It also includes young low-mass stars from the Gould Belt region whose radio observations were performed in continuum. Based on this, most complete sample of sources to date, we have estimated the velocities $U_{\odot}$, $V_{\odot}$, $W_{\odot}$ and the parameters of the angular velocity of Galactic rotation $\Omega_{0},\Omega^{(1)}_{0},\ldots,\Omega^{(4)}_{0}$ and obtained a new estimate of the distance from the Sun to the Galactic center, $R_{0}=8.15_{-0.20}^{+0.04}$ kpc. The parameters of the Galactic spiral density wave have been found from the series of radial, $V_{R}$, and residual tangential, $\Delta V_{\textrm{circ}}$, velocities of stars. The amplitudes of the radial and tangential velocity perturbations are $f_{R}=7.0\pm 0.9$ km s${}^{-1}$ and $f_{\theta}=3.8\pm 1.1$ km s${}^{-1}$, the perturbation wavelengths are $\lambda_{R}=2.3\pm 0.2$ kpc and $\lambda_{\theta}=2.0\pm 0.4$ kpc, and the Sun’s phases in the spiral density wave are $(\chi_{\odot})_{R}=-163^{\circ}\pm 9^{\circ}$ and $(\chi_{\odot})_{\theta}=-137^{\circ}\pm 10^{\circ}$ for the adopted four-armed spiral pattern.