Kinematics of OB Stars with Data from the LAMOST and Gaia Catalogues

V. V. Bobylev, A. T. Bajkova, G. M. Karelin

Submitted on 5 July 2022


We have analyzed the kinematics of OB stars from the list by Xiang et al. (2021) that contains 13 000 single OB stars. For these stars there are photometric distance estimates and proper motions from the Gaia catalogue and line-of-sight velocities from the LAMOST catalogue. Based on a sample of single OB stars and using the photometric distances and proper motions of stars from the Gaia EDR3 catalogue, we have found the group velocity components (U,V,W)=(9.63,9.93,7.45)±(0.27,0.34,0.10) km s1, and the following parameters of the angular velocity of Galactic rotation: Ω0=29.20±0.18 km s1 kpc1, Ω0=4.150±0.046 km s1 kpc2 and Ω0=0.795±0.018 km s1 kpc3, where the error per unit weight σ0 is 9.56 km s1 and V0=236.5±3.3 km s1 (for the adopted R0=8.1±0.1 kpc). Based on the same OB stars, we have found the residual velocity dispersions (σ1,σ2,σ3)=(15.13,9.69,7.98)±(0.07,0.05,0.04) km s1. We show that using the line-of-sight velocities increases significantly the space velocity dispersion and leads to a biased estimate of the velocity U. A comparison of the distances scales used has shown that the photometric distances from Xiang et al. (2021) should be lengthened approximately by 10%.


Comment: 19 pages, 5 figures, 4 tables

Subject: Astrophysics - Astrophysics of Galaxies