Distance and extinction determination for APOGEE stars with Bayesian method

TL;DR

This paper presents a Bayesian method to accurately determine distances and extinctions for over 100,000 APOGEE red giant stars, validated against multiple independent datasets, improving our understanding of stellar parameters in the Milky Way.

Contribution

The study introduces a novel Bayesian approach that integrates spectroscopic, photometric, and prior Galactic information to derive stellar distances and extinctions with high accuracy.

Findings

Distances agree within 4.2% to 3.6% of other methods.

Dispersion in distances ranges from 15% to 25%.

Extinction estimates align well with other methods, with some overestimation by RJCE for certain stars.

Abstract

Using a Bayesian technology we derived distances and extinctions for over 100,000 red giant stars observed by the Apache Point Observatory Galactic Evolution Experiment (APOGEE) survey by taking into account spectroscopic constraints from the APOGEE stellar parameters and photometric constraints from 2MASS, as well as a prior knowledge on the Milky Way. Derived distances are compared with those from four other independent methods, the Hipparcos parallaxes, star clusters, APOGEE red clump stars, and asteroseismic distances from APOKASC (Rodrigues et al. 2014) and SAGA Catalogues (Casagrande et al. 2014). These comparisons covers four orders of magnitude in the distance scale from 0.02 kpc to 20 kpc. The results show that our distances agree very well with those from other methods: the mean relative difference between our Bayesian distances and those derived from other methods ranges from -4.2% to +3.6%, and the dispersion ranges from 15% to 25%. The extinctions toward all stars are also derived and compared with those from several other independent methods: the Rayleigh-Jeans Color Excess (RJCE) method, Gonzalez's two-dimensional extinction map, as well as three-dimensional extinction maps and models. The comparisons reveal that, overall, estimated extinctions agree very well, but RJCE tends to overestimate extinctions for cool stars and objects with low logg.