The galactic globular cluster system - Calibration of the ratio R = N(HB)/N(RGB)

Bibcode
1987A&A...183..228C
Caputo, F.; Martinez Roger, C.; Paez, E.
Bibliographical reference

Astronomy and Astrophysics (ISSN 0004-6361), vol. 183, no. 2, Sept. 1987, p. 228-233.

Advertised on:
9
1987
Number of authors
3
IAC number of authors
2
Citations
66
Refereed citations
59
Description
On the basis of Synthetic Horizontal Branches computed with Sweigart and Gross (1976) Horizontal Branch evolutionary tracks, and by means of Sweigart and Gross (1978) Red Giant Branch star models, the calibration of the ratio R = N(HB)/N(RGB) in terms of helium abundance (Y), He-core mass (Mc) and Horizontal Branch morphology is derived. The results obtained in the present paper confirm that the estimate for Y is independent of the Horizontal Branch morphology, at least within the observed range of R-values and for clusters containing RR Lyrae variables. As far as the occurrence of enhanced He-core mass is concerned, the resulting estimate for Y increases by dY/dΔMc = 0.40. From star counts in some well studied RR Lyrae rich globular clusters a mean value for Y equal to 0.24±0.01 is obtained.
Type
Refereed
Variable stars

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