Kinematics and Velocity Ellipsoid of Halo Red Giants

Abstract

In the present paper, we aim to determine the kinematical properties, velocity ellipsoid, and Oort constants using a sample of halo red giants. The study is based mainly on the space and radial velocities of about 1583 red giant stars collected from the SEGUE-1 and SEGUE-2 surveys. We divided the sample into three subsamples, the inner halo, the outer halo and the stars near the galactic plane. The fitting of the radial velocity equation gives a the mean of Oort constants, A = 15.6 +- 1.6 km s-1 kpc-1 and B= -13.9 +- 1.8 km s-1 kpc-1, the angular velocity |A-B|= 29.5 +- 0.2 km s-1 kpc-1 implying a rotational velocity of 221.25 +- 26.66 km s-1 if we take the distance to the Galactic center as 7.5 kpc.

arXiv comment15 pages, 3 figures. arXiv admin note: text overlap with arXiv:0706.3005 by other authors

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