PSF Photometry of HST ACS/HRC Images of CGCG 269-049
Abstract
We present HST ACS/HST images and PSF photometry of the resolved stellar population within star-forming dwarf galaxy CGCG 269-049. At a distance of only 5 Mpc, this galaxy is one of the most metal-poor known, with 12+log(O/H) = 7.43. Claims in the recent literature that the handful of extreme objects like CGCG 269-049 that are presently forming their very first generation of stars -- i.e., that these galaxies are the counterparts of the galaxies seen at the highest redshifts -- are highly controversial. Our F330W, F550M, and F814W photometry of the CGCG 269-049 images reveals a large population of red giant and asymptotic giant branch stars, which rules out the possibility that CGCG 269-049 is a young galaxy. We also estimated the mass fraction of old, > 1 Gyr--10Gyr, stars in this galaxy, which is 60--90%, depending on the choice of the initial mass functions. These galaxies are therefore useful objects to study as possible local descendants of the dwarf galaxies that finished cosmic reionization at z >= 6.
Funding for this project was provided by NASA grant GO-10843.01-A from STScI, which is operated by AURA under NASA contract NAS5-26555.- Publication:
-
American Astronomical Society Meeting Abstracts
- Pub Date:
- December 2007
- Bibcode:
- 2007AAS...21110419K