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He-rich and He-poor populations in RGB stars. Results on a sample of 19 globular clusters

Published online by Cambridge University Press:  23 April 2010

Angela Bragaglia ,
Valentina D'Orazi ,
Raffaele Gratton ,
Eugenio Carretta ,
Santi Cassisi  and
Sara Lucatello
Angela Bragaglia
Affiliation:
INAF-Osservatorio Astronomico di Bologna, via Ranzani 1, 40127 Bologna, Italy email: [email protected], [email protected]
Valentina D'Orazi
Affiliation:
INAF-Osservatorio Astronomico di Padova, vicolo Osservatorio 5, 35122 Padova, Italy email: [email protected], [email protected], [email protected]
Raffaele Gratton
Affiliation:
INAF-Osservatorio Astronomico di Padova, vicolo Osservatorio 5, 35122 Padova, Italy email: [email protected], [email protected], [email protected]
Eugenio Carretta
Affiliation:
INAF-Osservatorio Astronomico di Bologna, via Ranzani 1, 40127 Bologna, Italy email: [email protected], [email protected]
Santi Cassisi
Affiliation:
INAF-Osservatorio Astronomico di Collurania, via M. Maggini, I-64100, Teramo, Italy email: [email protected]
Sara Lucatello
Affiliation:
INAF-Osservatorio Astronomico di Padova, vicolo Osservatorio 5, 35122 Padova, Italy email: [email protected], [email protected], [email protected]
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Abstract

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We use about 1400 red giant branch stars observed in 19 Galactic Globular Clusters (GCs) to compare colours, metallicities, and RGB bump luminosities of stars assigned to first and second generations. We find subtle differences which we attribute to the different He content. In general these differences are visible only when we consider the extreme second generation stars, with the exception of NGC 2808. When using various indicators, the implied helium enhancements are similar, but the absolute calibration is still uncertain.

Keywords

Stars: abundancesPopulation II – Galaxy: globular clusters
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 5 , Symposium S268: Light Elements in the Universe , November 2009 , pp. 169 - 170
Copyright
Copyright © International Astronomical Union 2010

References

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