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A Combined Photometric/Spectroscopic Study of RR Lyrae Stars in the Globular Cluster Omega Centauri

Published online by Cambridge University Press:  14 August 2015

Dennis Butler ,
Roger A. Bell ,
R. J. Dickens  and
Elizabeth Epps
Dennis Butler
Affiliation:
University of Maryland
Roger A. Bell
Affiliation:
University of Maryland
R. J. Dickens
Affiliation:
Royal Greenwich Observatory
Elizabeth Epps
Affiliation:
Royal Greenwich Observatory

Extract

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Most CM diagrams of well observed galactic globular clusters have giant branch widths which are understandable in terms of realistic estimates of random (and systematic) error associated with data acquisition and reduction. Not Omega Centauri. The scatter in (B-V) color among Omega Centauri giant branch stars is considerably greater than that allowed by observational error, differential reddening, or star-to-star mass and/or helium abundance variation (Demarque and Geisler 1963; Woolley 1966; Dickens and Woolley 1967; Rood 1973; Cannon and Stobie 1973; Cannon and Kontizas 1974; Iben 1974; Norris and Bessell 1975; Hesser et al. 1976; 1977). This problem is an old one, but one which has recently received a flurry of attention. Indeed, our next speakers have investigated possible causal relationships between interior mixing and Omega Centauri giant (or subgiant) color. I see from the program that they intend to discuss such things today, so we shall try to avoid those topics as much as possible.

Type
Part IV: HR Diagrams, Clusters
Information
Symposium - International Astronomical Union , Volume 80: The HR Diagram , 1978 , pp. 183 - 194
Copyright
Copyright © Reidel 1978 

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