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Astron. Astrophys. 359, 131-137 (2000)

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Resolved stellar populations of super-metal-rich star clusters in the bulge of M 31

P. Jablonka 1, F. Courbin 2, G. Meylan 3, A. Sarajedini 4, T.J. Bridges 5 and P. Magain 6

1 DAEC-URA 8631, Observatoire de Paris-Meudon, Place Jules Janssen, 92195 Meudon, France
2 Universidad Católica de Chile, Departamento de Astronoma y Astrofsica, Av. Vicuña Mackena 4860, Casilla 306, Santiago 22, Chile
3 European Southern Observatory, Karl-Schwarzschild-Strasse 2, 85748 Garching, Germany
4 Astronomy Department, Wesleyan University, Middletown, CT 06459, USA
5 Anglo-Australian Observatory, P.O. Box 296, Epping, NSW, 1710, Australia
6 Institut d'Astrophysique, Université de Liège, 5 Avenue de Cointe, 4000 Liège, Belgium

Received 23 February 2000 / Accepted 4 May 2000


We have applied the MCS image deconvolution algorithm (Magain et al. 1998) to HST/WFPC2 V, I data of three M 31 bulge globular clusters (G170, G177, and G198) and control fields near each cluster. All three clusters are clearly detected, with an increase in stellar density with decreasing radius from the cluster centers; this is the first time that stars have been resolved in bulge clusters in the inner regions of another galaxy. From the RGB slopes of the clusters and the difference in I magnitude between the HB and the top of the RGB, we conclude that these three clusters all have roughly solar metallicity, in agreement with earlier integrated-light spectroscopic measurements. Our data support a picture whereby the M 31 bulge clusters and field stars were born from the same metal-rich gas, early in the galaxy formation.

Key words: methods: data analysis – galaxies: formation – galaxies: individual: M 31 – galaxies: spiral – galaxies: star clusters – galaxies: stellar content

Send offprint requests to: P. Jablonka

Correspondence to: pascale.jablonka@obspm.fr

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© European Southern Observatory (ESO) 2000

Online publication: June 30, 2000