Estimation of Galactic Spiral Density Wave Parameters Based on the Velocities of OB2 stars from the Gaia EDR3 Catalogue

V. V. Bobylev, A. T. Bajkova

Submitted on 7 July 2022


We have analyzed the kinematics of 9750 OB2 stars with proper motions and parallaxes selected by Xu et al. from the Gaia EDR3 catalogue. The relative parallax errors for these stars do not exceed 10\%. Based on the entire sample of stars, we have found the velocities (U,V)=(7.17,7.37)±(0.16,0.24) km s1 and the components of the angular velocity of Galactic rotation: Ω0=29.700±0.076 km s1 kpc1, Ω0=4.008±0.022 km s1 kpc2, and Ω0=0.671±0.011 km s1 kpc3, where the linear rotation velocity of the Galaxy at the solar distance is V0=240.6±3.0 km s1 for the adopted R0=8.1±0.1 kpc. There are 1812 OB2 stars with measured line-of-sight velocities, and the space velocities VR and ΔVcirc have been calculated from them. Based on a spectral analysis independently for the radial and residual tangential velocities, we have obtained the following estimates: fR=4.8±0.7 km s1, fθ=4.1±0.9 km s1, λR=2.1±0.2 kpc, λθ=2.2±0.4 kpc, (χ)R=116±12, and (χ)θ=156±14 for the adopted four-armed (m=4) spiral pattern. Thus, both velocity perturbation amplitudes are nonzero at a high significance level.


Comment: 13 pages, 2 figures, 2 tables. arXiv admin note: text overlap with arXiv:2203.12902, arXiv:1903.09313, arXiv:1906.10151, arXiv:2207.01924

Subject: Astrophysics - Astrophysics of Galaxies