Peculiarities of Galactic rotation in the solar neighbourhood from data on Red Clump giants

Rybka, SP
Kinemat. fiz. nebesnyh tel (Online) 2008, 24(2):137-145
Language: Russian
Abstract: 

The local velocity field of more than 53000 Red Clump giants within one kiloparsec from the Sun was investigated by means of the three-dimensional Ogorodnikov-Milne model. These stars were identified to be the most probable Red Clump candidates from the «Tycho-2» catalogue. The values of galactic rotation parameters are presented for two stellar groups: \b\ 30°. It was shown that galactic rotation of the first stellar group has some peculiarities, which is confirmed by statistically significant values of phase offset parameter φ = 6.9±0.6° and contraction parameter K = -6.3 ±1.1 km ⋅ s-1kpc-1 in the framework of Ogorodnikov-Milne model. The velocity ellipsoid of both stellar groups and the motion of the Sun relative to these groups were also determined. The vertex deviation is found to vary most significantly with the star sample. Its value is 5.9±0.7° for Red Clump giants at \b\ 30°.

Keywords: Galactic rotation, Red Clump giant