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arXiv · 1703.06468

The Carnegie-Chicago Hubble Program. II. The Distance to IC 1613: The Tip of the Red Giant Branch and RR Lyrae Period-Luminosity Relations

Dylan Hatt·Rachael L. Beaton·Wendy L. Freedman·Barry F. Madore·In Sung Jang·Taylor J. Hoyt·Myung Gyoon Lee·Andrew J. Monson·Jeffrey A. Rich·Victoria Scowcroft·Mark Seibert
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Abstract

IC 1613 is an isolated dwarf galaxy within the Local Group. Low foreground and internal extinction, low metallicity, and low crowding make it an invaluable testbed for the calibration of the local distance ladder. We present new, high-fidelity distance estimates to IC 1613 via its Tip of the Red Giant Branch (TRGB) and its RR Lyrae (RRL) variables as part of the Carnegie-Chicago Hubble Program, which seeks an alternate local route to \ho using Population II stars. We have measured a TRGB magnitude I=20.35+/-0.01 (statistical)+/-0.01 (systematic) using wide-field observations obtained from the IMACS camera on the Magellan-Baade telescope. We have further constructed optical and near-infrared RRL light curves using archival BI- and new H- band observations from the ACS/WFC and WFC3/IR instruments aboard the Hubble Space Telescope (HST). In advance of future Gaia data releases, we set provisional values for the TRGB luminosity via the Large Magellanic Cloud and Galactic RRL zero-points via HST parallaxes. We find corresponding true distance moduli μ(TRGB)=24.30+/-0.03 (statistical)+/-0.05 (systematic) and μ(RRL)=24.28+/-0.04 (statistical+systematic). We compare our results to a body of recent publications on IC 1613 and find no statistically significant difference between the distances derived from stars of Population I and II.

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Dylan Hatt, Rachael L. Beaton, Wendy L. Freedman, Barry F. Madore, In Sung Jang, Taylor J. Hoyt, Myung Gyoon Lee, Andrew J. Monson, Jeffrey A. Rich, Victoria Scowcroft, Mark Seibert. 2017-10-10. The Carnegie-Chicago Hubble Program. II. The Distance to IC 1613: The Tip of the Red Giant Branch and RR Lyrae Period-Luminosity Relations. https://doi.org/10.3847/1538-4357%2Faa7f73

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