Stellar Content and Recent Star Formation History of the Local Group Dwarf Irregular Galaxy IC 1613

Bernard, Edouard J.; Aparicio, Antonio; Gallart, Carme; Padilla-Torres, Carmen P.; Panniello, Maurizio
Bibliographical reference

The Astronomical Journal, Volume 134, Issue 3, pp. 1124-1132 (2007).

Advertised on:
9
2007
Number of authors
5
IAC number of authors
5
Citations
32
Refereed citations
28
Description
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 μV,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) × 10-3 Modot yr-1 kpc-2 in the central r lesssim 2.5' for the last 300 Myr. Based on observations made with the Isaac Newton Telescope, operated on the island of La Palma by the Isaac Newton Group, in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias.