Galactic Rotation Based on OB Stars from the Gaia DR2 Catalogue. (arXiv:1906.10151v1 [astro-ph.GA])
<a href="http://arxiv.org/find/astro-ph/1/au:+Bobylev_V/0/1/0/all/0/1">V.V. Bobylev</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bajkova_A/0/1/0/all/0/1">A.T. Bajkova</a>

We have studied a sample containing about 6000 OB stars with proper motions
and trigonometric parallaxes from the Gaia DR2 catalogue. The following
parameters of the angular velocity of Galactic rotation have been found:
$Omega_0=29.70pm0.11$ km s$^{-1}$ kpc$^{-1}$, $Omega’_0=-4.035pm0.031$ km
s$^{-1}$ kpc$^{-2}$, and $Omega”_0= 0.620pm0.014$ km s$^{-1}$ kpc$^{-3}$.
The circular rotation velocity of the solar neighborhood around the Galactic
center is $V_0=238pm5$ km s$^{-1}$ for the adopted Galactocentric distance of
the Sun $R_0=8.0pm0.15$ kpc. The amplitudes of the tangential and radial
velocity perturbations produced by the spiral density wave are
$f_theta=4.4pm1.4$ km s$^{-1}$ and $f_R=5.1pm1.2$ km s$^{-1}$, respectively;
the perturbation wavelengths are $lambda_theta=1.9pm0.5$ kpc and
$lambda_R=2.1pm0.5$ kpc for the adopted four-armed spiral pattern. The Sun’s
phase in the spiral density wave is $chi_odot=-178^circpm12^circ$.

We have studied a sample containing about 6000 OB stars with proper motions
and trigonometric parallaxes from the Gaia DR2 catalogue. The following
parameters of the angular velocity of Galactic rotation have been found:
$Omega_0=29.70pm0.11$ km s$^{-1}$ kpc$^{-1}$, $Omega’_0=-4.035pm0.031$ km
s$^{-1}$ kpc$^{-2}$, and $Omega”_0= 0.620pm0.014$ km s$^{-1}$ kpc$^{-3}$.
The circular rotation velocity of the solar neighborhood around the Galactic
center is $V_0=238pm5$ km s$^{-1}$ for the adopted Galactocentric distance of
the Sun $R_0=8.0pm0.15$ kpc. The amplitudes of the tangential and radial
velocity perturbations produced by the spiral density wave are
$f_theta=4.4pm1.4$ km s$^{-1}$ and $f_R=5.1pm1.2$ km s$^{-1}$, respectively;
the perturbation wavelengths are $lambda_theta=1.9pm0.5$ kpc and
$lambda_R=2.1pm0.5$ kpc for the adopted four-armed spiral pattern. The Sun’s
phase in the spiral density wave is $chi_odot=-178^circpm12^circ$.

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