http://arxiv.org/abs/1809.10512
We have selected and analyzed a sample of OB stars with known line-of-sight velocities determined through ground-based observations and with trigonometric parallaxes and proper motions from the Gaia DR2 catalogue. Some of the stars in our sample have distance estimates made from calcium lines. A direct comparison with the trigonometric distance scale has shown that the calcium distance scale should be reduced by 13\%. The following parameters of the Galactic rotation curve have been determined from 495 OB stars with relative parallax errors less than 30\%:
$(U,V,W)\odot=(8.16,11.19,8.55)\pm(0.48,0.56,0.48)$ km s$^{-1}$,
$\Omega_0=28.92\pm0.39$ km s$^{-1}$ kpc$^{-1}$,
$\Omega^{‘}_0=-4.087\pm0.083$ km s$^{-1}$ kpc$^{-2}$ and
$\Omega^{”}_0=0.703\pm0.067$ km s$^{-1}$ kpc$^{-3}$, where the circular velocity of the local standard of rest is
$V_0=231\pm5$ km s$^{-1}$ (for the adopted $R_0=8.0\pm0.15$ kpc). The parameters of the Galactic spiral density wave have been found from the series of radial, $V_R,$ residual tangential, $\Delta V{circ}$, and vertical, $W,$ velocities of OB stars by applying a periodogram analysis. The amplitudes of the radial, tangential, and vertical velocity perturbations are
$f_R=7.1\pm0.3$ km s$^{-1}$,
$f_\theta=6.5\pm0.4$ km s$^{-1}$, and
$f_W=4.8\pm0.8$ km s$^{-1}$, respectively; the perturbation wavelengths are
$ \lambda_R=3.3\pm0.1$ kpc,
$\lambda_\theta=2.3\pm0.2$ kpc, and
$ \lambda_W=2.6\pm0.5$ kpc; and the Sun’s radial phase in the spiral density wave is
$ (\chi_\odot)R=-135\pm5^\circ$,
$(\chi\odot)\theta=-123\pm8^\circ$, and
$ (\chi\odot)_W=-132\pm21^\circ$ for the adopted four-armed spiral pattern.
V. Bobylev and A. Bajkova
Fri, 28 Sep 18
32/52
Comments: 16 pages,6 figures, 1 table
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