Deriving physical parameters of unresolved star clusters⋆
V. M 31 PHAT star clusters
1 Center for Physical Sciences and Technology, Saulėtekio av. 3, 10257 Vilnius, Lithuania
2 Vilnius University Observatory, Čiurlionio 29, 03100 Vilnius, Lithuania
Received: 8 March 2017
Accepted: 29 March 2017
Context. This study is the fifth of a series that investigates the degeneracy and stochasticity problems present in the determination of physical parameters such as age, mass, extinction, and metallicity of partially resolved or unresolved star cluster populations in external galaxies when using HST broad-band photometry.
Aims. In this work we aim to derive parameters of star clusters using models with fixed and free metallicity based on the HST WFC3+ACS photometric system. The method is applied to derive parameters of a subsample of 1363 star clusters in the Andromeda galaxy observed with the HST.
Methods. Following Paper III, we derive the star cluster parameters using a large grid of stochastic models that are compared to the six observed integrated broad-band WFC3+ACS magnitudes of star clusters.
Results. We show that the age, mass, and extinction of the M 31 star clusters, derived assuming fixed solar metallicity, are in agreement with previous studies. We also demonstrate the ability of the WFC3+ACS photometric system to derive metallicity of star clusters older than ~1 Gyr. We show that the metallicity derived using broad-band photometry of 36 massive M 31 star clusters is in good agreement with the metallicity derived using spectroscopy.
Key words: galaxies: individual: M 31 / galaxies: star clusters: general
Table 1 is only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (220.127.116.11) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/602/A112
© ESO, 2017