A New Red Giant–based Distance Modulus of 13.3 Mpc to the Antennae Galaxies and Its Consequences
Publication date: 10 May 2008
Authors: Saviane, I. et al.
Journal: The Astrophysical Journal
Volume: 678
Issue: 1
Page: 179-186
Year: 2008
Copyright: The American Astronomical Society
The Antennae galaxies are the closest example of an ongoing major galaxy merger and, as such, represent a unique laboratory for furthering the understanding of the formation of exotic objects (e.g., tidal dwarf galaxies, ultraluminous X-ray sources, super stellar clusters). In a previous paper HST WFPC2 observations were used to demonstrate that the Antennae system might be at a distance considerably less than that conventionally assumed in the literature. Here we report new, much deeper HST ACS imaging that resolves the composite stellar populations and, most importantly, reveals a well-defined red giant branch. The tip of this red giant branch (TRGB) is unambiguously detected at I0TRGB=26.65+-0.09 mag. Adopting the most recent calibration of the luminosity of the TRGB then yields a distance modulus for the Antennae of (m-M)0 = 30.62+-0.17 corresponding to a distance of 13.3+-1.0 Mpc. This is consistent with our earlier result, once the different calibrations for the standard candle are considered. We briefly discuss the implications of this now well-determined shorter distance.
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