Presentation #420.04 in the session Large Scale Structure, Cosmic Distance Scale II.
The J-region Asymptotic Giant Branch (JAGB) method is a powerful new extragalactic distance indicator that uses the mean J-band magnitude of a color-selected subset of carbon stars as a standard candle. We present an updated zeropoint for the JAGB method derived from a combination of LMC and SMC detached eclipsing binary (DEB) distances and Gaia EDR3 Milky Way parallaxes. Then, using high-precision near-infrared photometry obtained from the FourStar near-infrared camera on the 6.5 m Baade-Magellan telescope at Las Campanas, we apply the JAGB method to measure distances to six nearby galaxies. We find excellent agreement with previously published distances based on the TRGB, indicating that the JAGB method has enormous potential for an independent determination of the Hubble constant via a type Ia supernovae distance ladder, comparable in accuracy and precision to the Tip of the Red Giant Branch (TRGB) and the Cepheid Leavitt Law.