Milky Way Zero-point Calibration of the JAGB Method: Using Thermally Pulsing AGB Stars in Galactic Open Clusters

Abstract

We present a new calibration of the J -band absolute magnitude of the JAGB method based on thermally pulsing AGB stars that are members of Milky Way open clusters, having distances and reddenings, independently compiled and published by Marigo. A total 17 of these photometrically selected J-Branch AGB stars give M J = −6.40 mag with a scatter of ±0.40 mag, and 1 σ on the mean of ±0.10 mag. Combining the Milky Way field carbon star calibration of Lee with this determination gives a weighted average of M J (MW) = −6.19 ± 0.04 mag (error on the mean). This value is statistically indistinguishable from the value determined for this population of distance indicators in the LMC and SMC, giving further evidence that JAGB stars are extremely reliable distance indicators of high luminosity and universal applicability. Combining the zero-points for JAGB stars in these three systems, a value of M J = −6.20 ± 0.01 (stat) ±0.04 (sys) mag becomes our best current estimate of the JAGB zero-point and its associated errors. Finally, we note that no evidence is found for any statistically significant dependence of this zero-point on metallicity.