Spectral Types of Stars in the Globular Clusters Messier 3 and Messier 13.
Abstract
Spectral classifications have been obtained for fourteen stars in Messier 3 and for twenty-one stars in Messier 13. The brightest stars, which have absolute photovisual magnitudes between -2 and -3 and color indices principally between +0.9 and + 1.6 mag., are of spectral type G5-KO and luminosity class Tb. They are peculiar in that the CN absorption shortward from X 4215 is weak. This result is in agreement with an early observation by Lindblad and with Baade's grouping of the globular-cluster stars in the same population group as the high-velocity stars. Among the brightest members of each cluster is' at least one 0 or B star. Approximate magnitudes and colors have been obtained for the bright- est stars in the central regions of the two clusters. These observations augment Shapley's photometry and show that a large fraction of the brightest stars are to be found in the central regions: The dispersion in radial velocity of the most massive stars in Messier 13 is not more than a few kilometers per second
- Publication:
-
The Astrophysical Journal
- Pub Date:
- January 1947
- DOI:
- 10.1086/144893
- Bibcode:
- 1947ApJ...105..204P