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

TL;DR

This paper calibrates the J-band absolute magnitude of JAGB stars using Milky Way open clusters, confirming their reliability as universal distance indicators with a new zero point estimate.

Contribution

The study provides the first calibration of the JAGB zero point based on Milky Way open cluster stars, enhancing the method's accuracy and universality.

Findings

JAGB stars have M_J = -6.20 mag with minimal systematic error.

The zero point shows no significant metallicity dependence.

Calibration aligns with values from LMC and SMC, confirming universality.

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 et al (2022). 17 of these photometrically-selected J-Branch AGB stars give M_J = -6.40 mag with a scatter of +/-0.40 mag, and a sigma on the mean of +/-0.10 mag. Combining the Milky Way field carbon star calibration of Lee et al. (2021) 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.