RevMexAA: Abstracts of Accepted Papers for Volume 47 Number 2


March 23, 2011

2011: March



March 2011


The Kinematics and Velocity Ellipsoid of the G III Stars

Richard L. Branham, Jr.

Instituto Argentino de Nivologa, Glaciologa y Ciencias Ambientales, Mendoza, Argentina

richardbranham_1943@yahoo.com

Received: 2010 October 27
Accepted: 2011 March 10

Abstract: To study the kinematics of the G giant stars (luminosity class III) use is made of proper motions and parallaxes taken from van Leeuwens new reduction of the Hipparcos catalog. 3,075 stars, of which 658 have radial velocities, were used in the nal study. The solution gives: solar velocity of 16.72 ± 0.41 km s-1; Oorts constants, in units of km s-1 kpc-1, A = 14.05 ± 3.28 and B = -9.30 ± 2.87, implying a rotational velocity of 198.48 ± 26.95 km s-1 if we take the distance to the Galactic center as 8.2 ± 1.1 kpc; velocity dispersions, in units of km s-1, of σx = 51.78 ± 0.55, σy = 42.81 ± 0.32, σz = 28.45 ± 0.22 with a vertex deviation of 3.88 ± 6.62. A comparison of the velocity dispersions with those given by other spectral types shows that Parenagos discontinuity also exists for the giant stars.