Kinematics of nearby subdwarf stars
Astronomisches Rechen-Institut, Mönchhofstraße 12-14, 69120 Heidelberg, Germany e-mail: arifyanto@ari.uni-heidelberg.de
Received:
9
December
2003
Accepted:
10
December
2004
We present an analysis of the space motions of 742
subdwarf stars based on the sample of Carney et al. (1994, AJ, 107, 22
40). Hipparcos parallaxes, TYC2+HIP proper
motions and Tycho 2 proper motions were combined with radial
velocities and metallicities from CLLA. The kinematical behavior
is discussed in particular in relation to their metallicities. The
majority of these sample stars have metal abundances of [Fe/H] 
and represent the thick disk population. The halo component,
with [Fe/H] 
, is characterized by a low mean rotation
velocity and a radially elongated velocity ellipsoid. In the
intermediate metallicity range (
[Fe/H] 
), we
find a significant number of subdwarfs with disklike
kinematics. We interpret this population of stars as a metal-weak
thick disk (MWTD) population.
Key words: stars: subdwarfs / Galaxy: kinematics and dynamics / Galaxy: solar neighbourhood
© ESO, 2005