BAFFLES: Bayesian Ages for Field Lowermass Stars
Abstract
Age is a fundamental parameter of stars, yet in many cases, ages of individual stars are presented without robust estimates of the uncertainty. We have developed a Bayesian framework, BAFFLES, to produce the age posterior for a star from its calcium emission strength (log( ${R}_{{HK}}^{{\prime} }$ )) or lithium abundance (Li EW) and B  V color. We empirically determine the likelihood functions for calcium and lithium as functions of age from literature measurements of stars in benchmark clusters with welldetermined ages. We use a uniform prior on age, which reflects a uniform star formation rate. The age posteriors we derive for several test cases are consistent with literature ages found from other methods. BAFFLES represents a robust method to determine the age posterior probability distribution for any field star with 0.45 ≤ B  V ≤ 0.9 and a measurement of ${R}_{{HK}}^{{\prime} }$ and/or 0.35 ≤ B  V ≤ 1.9 and measured Li EW. We compile colors, ${R}_{{HK}}^{{\prime} }$ , and Li EW from over 2630 nearby field stars from the literature, and present the derived BAFFLES age posterior for each star.
 Publication:

The Astrophysical Journal
 Pub Date:
 July 2020
 DOI:
 10.3847/15384357/ab9a35
 arXiv:
 arXiv:2006.04811
 Bibcode:
 2020ApJ...898...27S
 Keywords:

 Stellar activity;
 Stellar ages;
 Field stars;
 Bayesian statistics;
 1580;
 1581;
 2103;
 1900;
 Astrophysics  Solar and Stellar Astrophysics;
 Astrophysics  Earth and Planetary Astrophysics;
 Astrophysics  Astrophysics of Galaxies
 EPrint:
 Accepted to ApJ, 80 pages, 14 figures, 3 tables