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Do the OH/IR stars within 100 pc of the Galactic Center belong to the disk population?

Published online by Cambridge University Press:  07 August 2017

A.E. Whitford*
Affiliation:
Lick Observatory, University of California Santa Cruz, California 95064 USA

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The 135 OH/IR stars within 0.8 deg (∼ 100 pc) of the Galactic Center (GC) identified in a search with the VLA (Lindqvist et al. 1991) are in rapid rotation about the center with a regression line showing a velocity gradient of 1.2±0.1 km s−1, equivalent to 178 km s—1 deg−1 for Ro = 8.5 kpc (Lindqvist et al. 1992). This is of the same order as the inward extrapolation of the Galactic rotation curve derived from the terminal velocities of HI for l < 2 deg (Burton and Gordon 1978) and the general trend of the velocities of the CO clouds in the equatorial disk mapped by Dame et al. (1987) (Fig. 1b). These OH/IR stars are located along the ridge of highest projected CO density. This spatial location and the flat configuration argue for assignment to the disk population, a possibility suggested by Feast (1989). The VLA objects are not in general supergiants (Blommaert et al. 1992). On a K-band map of an area 1×2 deg around the GC, Catchpole et al. (1990) found a number of stars brighter than (mK)o = 5. On the assumption that BCK = 3.3, (Frogel and Whitford 1987), and Ro = 8.5 kpc, Mbol < — 6.3, i.e., in the supergiant range.

Type
Contributed Papers
Copyright
Copyright © Kluwer 1993 

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