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Session 9 - Dwarf Galaxies.
Display session, Monday, June 10
We have used the Hubble Space Telescope to observe the resolved stars of the nearby (D = 1.4 Mpc) dwarf irregular galaxy Sextans A. The data consist of WF/PC2 images in 3 bands: F439W (1 hour), F555W (30 minutes), and F814W (30 minutes). The stellar photometry was extracted using the DoPHOT program developed by Schechter, Mateo amp; Saha (1993, PASP, 105, 1342) with modifications for WF/PC2 data by Saha et al. (1996, ApJ, submitted). From this photometry, we were able to construct color-magnitude diagrams (CMD) and color-color diagrams down to a limiting magnitude of 26 in V. The CMD shows excellent detail. The main sequence, blue-loop stars, red supergiants, and red giant branch are all clearly distinct distributions in the CMDs. From these diagrams, we can constrain the star formation history of Sextans A through a statistical comparison with stellar evolution models.
Program listing for Monday