OH/IR stars close to the galactic centre. II. Their spatial and kinematics properties and the mass distribution within 5-100 PC from the galactic centre.
Abstract
An analysis of a sample of OH/IR stars close to the Galactic Center (GC) has been performed. The dispersion in radial velocity and the dispersion in galactic latitude are both correlated with the envelope expansion velocity. The surface density distribution of the OH/IR stars within 30 pc from the GC (projected distance) has a peak which agrees with the position of Sgr A* within the errors. The surface density distribution agrees quite well with the distribution of stars at 2.2 microns. There is a correlation between the radial velocity of the stars and the galactic longitude. Fifteen stars closer than 8 pc from the GC follow a much steeper rotation curve than the rest of the stars. This is in agreement with infrared measurements (Rieke & Rieke 1988; McGinn et al. 1989). We have calculated the enclosed mass as a function of distance from the GC using the Boltzmann equation and assuming a spherical potential and an isotropic velocity distribution. The mass connects well to the mass determined by McGinn et al. (1989) inside 10 pc from the GC. It is somewhat lower than the mass determined from the diffuse 2 micron emission assuming a mass-to-luminosity ratio of unity.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- June 1992
- Bibcode:
- 1992A&A...259..118L
- Keywords:
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- Galactic Nuclei;
- Hydroxyl Emission;
- Infrared Stars;
- Mass Distribution;
- Spatial Distribution;
- Stellar Motions;
- Milky Way Galaxy;
- Velocity Distribution;
- Astrophysics