Evidence for metallicity spreads in three massive M 31 globular clusters
Abstract
Aims. We quantify the intrinsic width of the red giant branches of three massive globular clusters in M 31 in a search for metallicity spreads within these objects. Methods. We present HST/ACS observations of three massive clusters in M 31, G78, G213, and G280. A thorough description of the photometry extraction and calibration is presented. After derivation of the color-magnitude diagrams, we quantify the intrinsic width of the red giant branch of each cluster. Results. This width translates into a metallicity dispersion that indicates a complex star formation history for this type of system. For G78, σ[Fe/H] = 0.86 ± 0.37; for G213, 0.89 ± 0.20; and for G280, 1.03 ± 0.26. We find that the metallicity dispersion of the clusters does not scale with mean metallicity. We also find no trend with the cluster mass. We discuss some possible formation scenarios that would explain our results.
Additional Information
© ESO 2008. Article published by EDP Sciences. (Received 22 October 2007 / Accepted 14 March 2008) I.F.C. acknowledges the financial support of FAPESP grant no.03/01625-2 and the Sixth Program of the EU for a Marie Curie Fellowship. AS was partially supported by STScI grant HST-GO-09719.01-A. S.G.D. acknowledges a partial support from the STScI grant HST-GO-09719.03-A, and the Ajax Foundation. I.F.C. also thanks D.R. Gonçalves and H. Flores for computational support. Note added in proof. Since this paper was accepted for publication, it has been noted that we did not take into account the effect of differential reddening on the width of the cluster RGBs. However, for a number of reasons (e. g. our small field of view,the small absolute reddenings of our clusters), we believe that this effect is likely to be negligible. We thank Ivan King for bringing this to our attention.Attached Files
Published - FUEaanda08.pdf
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Additional details
- Eprint ID
- 12731
- Resolver ID
- CaltechAUTHORS:FUEaanda08
- 03/01625-2
- Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
- European Union
- HST-GO-09719.01-A
- Space Telescope Science Institute, Hubble Fellow
- HST-GO-09719.03-A
- Space Telescope Science Institute
- Ajax Foundation
- Created
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2008-12-22Created from EPrint's datestamp field
- Updated
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2021-11-08Created from EPrint's last_modified field