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Calcium Abundance in the RR Lyrae Stars in NGC 3201 and M 5

Published online by Cambridge University Press:  14 August 2015

C. Cacciari  and
K. C. Freeman
C. Cacciari
Affiliation:
Mount Stromlo and Siding Spring Observatories, Australia Bologna Observatory, Italy
K. C. Freeman
Affiliation:
Mount Stromlo and Siding Spring Observatories, Australia

Extract

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The assumption that individual globular clusters formed from chemically homogeneous protosystems, which seems to be valid for some clusters, is clearly not valid in others, e.g., ω Cen and M22 (see Freeman and Rodgers 1975, Hesser, Hartwick and McClure 1976, Butler, Dickens and Epps 1978 and references quoted therein). One indicator of chemical inhomogeneity is the width of the cluster giant branch in the C-M diagram, because the B-V colors for the cool giants are sensitive to heavy element abundance. NGC 3201 and M 5 show narrow giant branches (Lee 1977, Arp 1962) and so are not expected to show large star-to-star heavy element differences.

Type
August 30 Globular Clusters
Information
Symposium - International Astronomical Union , Volume 85: Star Clusters , 1980 , pp. 427 - 428
Copyright
Copyright © Reidel 1980 

References

Arp, H.C.: 1962, Astrophys. J. 135, 311.Google Scholar
Butler, D., Dickens, R.J., and Epps, E.: 1978, Astrophys. J. 225, 148.Google Scholar
Freeman, K.C. and Rodgers, A.W.: 1975, Astrophys. J. Letters 201, L71.Google Scholar
Hesser, J.E., Hartwick, F.D.A., and McClure, R.D.: 1976, Astrophys. J. Letters 207, L113.Google Scholar
Lee, S.W.: 1977, Astron. Astrophys. Suppl. 28, 409.Google Scholar
Manduca, A. and Bell, R.A.: 1978, Astrophys. J. 225, 908.CrossRefGoogle Scholar