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

Journal Article · Sun Aug 20 04:00:00 EDT 2017 · Astrophysical Journal

DOI:https://doi.org/10.3847/1538-4357/AA7F73· OSTI ID:22875894

Hatt, Dylan; Freedman, Wendy L.; Madore, Barry F.; Hoyt, Taylor J. ^[1]; Beaton, Rachael L.; Rich, Jeffrey A.; Seibert, Mark ^[2]; Jang, In-Sung ^[3]; Lee, Myung Gyoon ^[4]; Monson, Andrew J. ^[5]; Scowcroft, Victoria ^[6]

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1. Department of Astronomy and Astrophysics, University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637 (United States)
2. Observatories of the Carnegie Institution for Science 813 Santa Barbara St., Pasadena, CA 91101 (United States)
3. Leibniz-Institut für Astrophysik Potsdam, D-14482 Potsdam (Germany)
4. Department of Physics and Astronomy, Seoul National University, Gwanak-gu, Seoul 151-742 (Korea, Republic of)
5. Department of Astronomy and Astrophysics, Pennsylvania State University, 525 Davey Lab, University Park, PA 16802 (United States)
6. Department of Physics, University of Bath, Claverton Down, Bath, BA2 7AY (United Kingdom)

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 H {sub 0} using Population II stars. We have measured a TRGB magnitude I{sub ACS}{sup TRGB}=20.35±0.01{sub stat}±0.01{sub sys} mag 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 on board 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{sub 0}{sup TRGB}=24.30±0.03{sub stat}±0.05{sub sys} mag and 〈μ{sub 0}{sup RRL}〉=24.28±0.04{sub stat+sys} mag. We compare our results to a body of recent publications on IC 1613 and find no statistically significant difference between the distances derived from Population I and II stars.

• OSTI ID: 22875894
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 845; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
CALIBRATION
COMPARATIVE EVALUATIONS
DISTANCE
LUMINOSITY
MAGELLANIC CLOUDS
METALLICITY
SPACE
TELESCOPES
VARIABLE STARS