A Triple Main Sequence in the Globular Cluster NGC 2808

Accurate photometry with HSTs ACS shows that the main sequence (MS) of the globular cluster NGC 2808 splits into three separate branches. The three MS branches may be associated with the complexities of the cluster's horizontal branch and of its abundance distribution. We attribute the MS branc...

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Veröffentlicht in:	The Astrophysical journal 2007-05, Vol.661 (1), p.L53-L56
Hauptverfasser:	Piotto, G, Bedin, L. R, Anderson, J, King, I. R, Cassisi, S, Milone, A. P, Villanova, S, Pietrinferni, A, Renzini, A
Format:	Artikel
Sprache:	eng
Schlagworte:	Astronomy Earth, ocean, space Exact sciences and technology
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Zusammenfassung:	Accurate photometry with HSTs ACS shows that the main sequence (MS) of the globular cluster NGC 2808 splits into three separate branches. The three MS branches may be associated with the complexities of the cluster's horizontal branch and of its abundance distribution. We attribute the MS branches to successive rounds of star formation, with different helium abundances; we discuss possible sources of helium enrichment. Some other massive globulars also appear to have complex populations; we compare them with NGC 2808.
ISSN:	1538-4357 0004-637X 1538-4357
DOI:	10.1086/518503