2007AJ....134.1124B

We present resolved-star VI photometry of the Local Group dwarf irregular galaxy IC 1613 reaching I∼23.5, obtained with the wide-field camera at the 2.5 m Isaac Newton Telescope. A fit to the stellar density distribution shows an exponential profile of scale length 2.9'±0.1' and gives a central surface brightness µ_V,0=22.7±0.6. The significant number of red giant branch (RGB) stars present in the outer part of our images (r>16.5') indicates that the galaxy is actually more extended than previously estimated. A comparison of the color-magnitude diagrams (CMDs) as a function of galactocentric distance shows a clear gradient in the age of its population, the scale length increasing with age, while we find no evidence of a metallicity gradient from the width of the RGB. We present quantitative results of the recent star formation history from a synthetic CMD analysis using IAC-STAR. We find a mean star formation rate of (1.6±0.8)x10^–3 M_☉/yr/kpc2 in the central r≲2.5' for the last 300 Myr.