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

We have analyzed the kinematics of 9750 OB2 stars with proper motions and parallaxes selected by Xu et al. from Gaia EDR3 catalogue. The relative parallax errors for these do not exceed 10 $${\%}$$ . Based on entire sample stars, we found velocities $$(U,V)_{\odot}=(7.17,7.37)\pm(0.16,0.24)$$ km s $${}^{-1}$$ components angular velocity Galactic rotation: $$\Omega_{0}=29.700\pm 0.076$$ kpc , $$\Omega^{\prime}_{0}={-}4.008\pm 0.022$$ $${}^{-2}$$ $$\Omega^{\prime\prime}_{0}=0.671\pm 0.011$$ $${}^{-3}$$ where linear rotation Galaxy at solar distance is $$V_{0}=240.6\pm 3.0$$ adopted $$R_{0}=8.1\pm 0.1$$ kpc. There are 1812 measured line-of-sight velocities, space $$V_{R}$$ $$\Delta V_{\rm circ}$$ been calculated them. a spectral analysis independently radial residual tangential obtained following estimates: $$f_{R}=4.8\pm 0.7$$ $$f_{\theta}=4.1\pm 0.9$$ $$\lambda_{R}=2.1\pm 0.2$$ kpc, $$\lambda_{\theta}=2.2\pm 0.4$$ $$(\chi_{\odot})_{R}={-}116^{\circ}\pm 12^{\circ}$$ $$(\chi_{\odot})_{\theta}={-}156^{\circ}\pm 14^{\circ}$$ four-armed ( $$m=4$$ ) spiral pattern. Thus, both perturbation amplitudes nonzero high significance level.