A Spitzer IRAC census of the asymptotic giant branch populations in local group dwarfs. II. IC 1613

We present Spitzer IRAC photometry of the Local Group dwarf irregular galaxy IC 1613. We compare our 3.6, 4.5, 5.8, and 8.0 μm photometry with broadband optical photometry and find that from the optical data we cannot detect 43% and that an additional 11% of the total AGB population are misidentified, likely because of extinction caused by circumstellar material. Furthermore, we find that a narrowband optical carbon star study of IC 1613 detects 50% of the total AGB population and only considers 18% of this population in calculating the carbon to M-type AGB ratio. We derive an integrated mass-loss rate from the AGB stars of (0.2-1.0) × 10 ^-3 M_⊙ yr^-1 and find that the distribution of bolometric luminosities and mass-loss rates are consistent with those for other nearby metal-poor galaxies. Both the optical completeness fractions and mass-loss rates in IC 1613 are very similar to those in the Local Group dwarf irregular galaxy WLM, which is expected, given their similar characteristics and evolutionary histories.