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Photometric Classification of Blue Horizontal-Branch Stars

Published online by Cambridge University Press:  14 August 2015

A. G. Davis Philip
A. G. Davis Philip*
Affiliation:
Dudley Observatory and State University of New York at Albany

Abstract

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The Strömgren four-color system has been used to classify blue horizontal-branch stars in globular clusters and in the general field. A relation between δ log g (log gmain sequence–log gstar) and δc1 (c1observed–c1main sequence) has been determined which gives log g to within ±0.2 for stars with log g's between 4.4 and 2.0. Newell (1970) has determined a relation between (B–V)0 and θe. Thus the gravities and effective temperatures of blue horizontal-branch stars can be determined from photometric measures alone. Five globular clusters have been studied at the present time. The BHB stars in the globular cluster M3 and M13 have lower surface gravities than BHB stars in the other clusters studied. Iben and Rood (1970) have recently suggested that the BHB stars of M3 may have lost more mass than BHB stars in more metal poor clusters.

Type
Part III: Photometric Classification
Information
Symposium - International Astronomical Union , Volume 50: Spectral Classification and Multicolour Photometry , 1973 , pp. 230 - 244
Copyright
Copyright © Reidel 1973 

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