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 $Ω₀,Ω^{(1)}₀,\ldots,Ω^{(4)}₀$ and obtained a new estimate of the distance from the Sun to the Galactic center, $R₀=8.15_{-0.20}^{+0.04}$ kpc. The parameters of the Galactic spiral density wave have been found from the series of radial, $V_R$, and residual tangential, $Δ V_{\textrm{circ}}$, velocities of stars. The amplitudes of the radial and tangential velocity perturbations are $f_R=7.0± 0.9$ km s${}^{-1}$ and $f_{θ}=3.8± 1.1$ km s${}^{-1}$, the perturbation wavelengths are $λ_R=2.3± 0.2$ kpc and $λ_{θ}=2.0± 0.4$ kpc, and the Sun's phases in the spiral density wave are $(χ_{\odot})_R=-163^{\circ}± 9^{\circ}$ and $(χ_{\odot})_{θ}=-137^{\circ}± 10^{\circ}$ for the adopted four-armed spiral pattern.