Bayesian Ages For Field LowEr-mass Stars

We have developed a Bayesian framework, BAFFLES, to produce the age posterior for a star from its calcium emission strength (log(R_HK_^'^)) 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 well-determined 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-V0.9 and a measurement of R_HK_^'^ and/or 0.35<=B-V<=1.9 and measured Li EW.