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| Paper: |
Self-Consistent Chemical Abundances and Star Formation Histories of Dwarf Irregular Galaxies |
| Volume: |
147, Abundance Profiles: Diagnostic Tools for Galaxy History |
| Page: |
133 |
| Authors: |
Skillman, Evan D.; Dohm-Palmer, Robbie C.; Kobulnicky, Henry A. |
| Abstract: |
Using Hubble Space Telescope WFPC2 photometry of the resolved stars in the nearby dwarf irregular galaxies Sextans A and Pegasus, we have constructed color-magnitude diagrams in V and I to a limit of 26 in V. We use the blue, core helium burning stars as a tracer of the star formation rate over the past 600 Myr in both galaxies. While Sextans A shows a relatively high star formation rate during this period, Pegasus has been relatively quiescent. From H\,Ii region observations we also find that the ISM in Pegasus shows a relatively high N/O ratio, while Sextans A shows a relatively low N/O ratio. These results are consistent with the hypothesis that oxygen production is dominated by high mass stars, while nitrogen production is dominated by intermediate to low mass stars. Thus, the star formation history as recorded in the stars is consistent with the star formation history inferred from the ISM abundances. |
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