Clues on the rejuvenation of the S0 galaxy NGC 404 from the chemical abundance of its outer disk
arXiv:1306.3027 · doi:10.1088/2041-8205/772/2/L23
Abstract
The oxygen abundance of the outer disk of the nearby S0 galaxy NGC 404, a prototypical early-type galaxy with extended star formation, has been derived from the analysis of HII region spectra. The high mean value found, 12+log(O/H)=8.6 \pm 0.1, equivalent to approximately 80% of the solar value, argues against both the previously proposed cold accretion and recent merger scenarios as viable mechanisms for the assembly of the star-forming gas. The combination of the present-day gas metallicity with the published star formation history of this galaxy favors a model in which the recent star forming activity represents the declining tail of the original one.
Accepted for publication in the Astrophysical Journal Letters