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

C. Cacciari, K. C. Freeman
1980 Symposium - International astronomical union  
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
more » ... dance. 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.
doi:10.1017/s0074180900092275 fatcat:huztayykvvcp5i5ti6kr2afdjm