Compact Star Clusters in the M~31 Disk
Abstract
Based on Suprime-Cam high-resolution images, about 17.5 arcmin × 28.5 arcmin field of the southwest part of the disk of M 31 was surveyed for compact clusters of an apparent size less than ∼3 arcsec. UBVRI photometry of 285 compact cluster candidates was performed using Local Group Galaxy Survey (LGGS) archive images. Cluster colors indicate a wide range of ages, 1 Myr ⪉ t ⪉ 10 Gyr. About 50 bright (17.0 ⪉ V ⪉ 19.0) clusters were studied in detail, to reveal that their structure is similar to classic globular clusters, except for some irregularities, resembling the massive clusters in LMC and SMC. According to the results of
single stellar population (SSP) model fitting to the observed photometric data, main part of them are of intermediate mass, between that of Milky Way open clusters and that of Milky Way globular clusters (3.0 ⪉ log (m/m_{sun}) ⪉ 4.5). These intermediate-mass clusters have ages of 30 Myr ⪉ t ⪉ 3 Gyr and an average metallicity of [M/H] ∼ -0.4. These findings suggest that they are disk clusters of intermediate population, which are not well known in the Milky Way, and may serve as useful tools to understand the evolution of the galaxy disk.- Publication:
-
Panoramic Views of Galaxy Formation and Evolution
- Pub Date:
- October 2008
- Bibcode:
- 2008ASPC..399..431K