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Age as the Second Parameter in NGC 288/NGC 362?

Published online by Cambridge University Press:  03 August 2017

M. Catelan ,
M. Bellazzini ,
F. R. Ferraro ,
F. Fusi Pecci ,
S. Galleti  and
W. B. Landsman
M. Catelan
Affiliation:
Hubble Fellow, University of Virginia, Department of Astronomy, P.O. Box 3818, Charlottesville, VA 22903-0818, USA
M. Bellazzini
Affiliation:
Osservatorio Astr. di Bologna, via Ranzani 1, I-40126 Bologna, Italy
F. R. Ferraro
Affiliation:
Osservatorio Astr. di Bologna, via Ranzani 1, I-40126 Bologna, Italy
F. Fusi Pecci
Affiliation:
Osservatorio Astr. di Bologna, via Ranzani 1, I-40126 Bologna, Italy
S. Galleti
Affiliation:
Osservatorio Astr. di Bologna, via Ranzani 1, I-40126 Bologna, Italy
W. B. Landsman
Affiliation:
Raytheon ITSS, NASA GSFC, Greenbelt, MD 20771, USA

Abstract

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We derive the age difference between NGC 288 and NGC 362 using the bimodal horizontal branch (HB) of NGC 1851 as a “bridge” in the CMD analysis. Our results suggest that NGC 288 is older than both NGC 362 and NGC 1851 by ⋍ 2 ± 1 Gyr. A new grid of synthetic HBs discloses that age may be the second parameter (2ndP) for this pair provided that the Carretta & Gratton (1997) metallicity scale is to be preferred over the Zinn & West (1984) scale. In addition, the dispersion in ZAHB mass is found to be about twice as large in NGC 362 as in NGC 288, probably due to the much higher central density of the former.

Type
Part 1. The Star Clusters of Local Group Galaxies
Information
Symposium - International Astronomical Union , Volume 207: Extragalactic Star Clusters , 2002 , pp. 116 - 118
Copyright
Copyright © Astronomical Society of the Pacific 2002 

References

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