Journal
ASTRONOMICAL JOURNAL
Volume 133, Issue 3, Pages 1125-1137Publisher
IOP PUBLISHING LTD
DOI: 10.1086/511185
Keywords
galaxies : abundances; galaxies : evolution; galaxies : individual (M33); galaxies : stellar content; galaxies : structure; Local Group
Categories
Ask authors/readers for more resources
Studying the stellar populations in the outskirts of spiral galaxies can provide important constraints on their structure, formation, and evolution. To that end, we present VI photometry obtained with the Advanced Camera for Surveys for three fields located similar to 20'-30' in projected distance southeast of M33's nucleus (corresponding to approximately four to six visual scale lengths or similar to 9-13 kpc in deprojected radius). The color-magnitude diagrams reveal a mixed stellar population whose youngest constituents have ages no greater than similar to 100 Myr and whose oldest members have ages of at least several gigayears. The presence of stars as massive as 3-5M(circle dot) is consistent with global star formation thresholds in disk galaxies but could argue for a threshold in M33 that is on the low end of observational and theoretical expectations. The metallicity gradient as inferred by comparing the observed red giant branch (RGB) to the Galactic globular clusters is consistent with M33's inner disk gradient traced by several other studies. The surface density of the RGB stars drops off exponentially with a radial scale length of 4.7' +/- 0.1'. The scale length increases with age in a manner similar to the vertical scale height of several nearby late-type spirals. Based on the metallicity gradient, density gradient, and mixed nature of the stellar populations, we conclude that these fields are dominated by a disk population, although we cannot rule out the presence of a small halo component.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available