Age Determinations of the Hyades, Praesepe, and Pleiades via MESA Models with Rotation

Abstract The Hyades, Praesepe, and Pleiades are well-studied stellar clusters that anchor important secondary stellar age indicators. Recent studies have shown that main sequence turn off based ages for these clusters may depend on the degree of rotation in the underlying stellar models. Rotation induces structural instabilities that can enhance the chemical mixing of a star, extending its fuel supply. In addition, rotation introduces a modulation of the star’s observed magnitude and color due to the effects of gravity darkening. We aim to investigate the extent to which stellar rotation affects the age determination of star clusters. We utilize the MESA stellar evolution code to create models that cover a range of rotation rates corresponding to Ω/Ωc = 0.0–0.6 in 0.1 dex steps, allowing the assessment of variations in this dimension. The statistical analysis package, MATCH, is employed to derive ages and metallicities by fitting our MESA models to Tycho B T , V T , and 2MASS J, K s color–magnitude diagrams. We find that the derived ages are relatively insensitive to the effects of rotation. For the Hyades, Praesepe, and Pleiades clusters, we derive ages based on synthetic populations that model a distribution of rotation rates or a fixed rate. Across each case, the derived ages tend to agree roughly within errors, near 680, 590, and 110–160 Myr for the Hyades, Praesepe, and Pleiades clusters, respectively. These ages are in agreement with Li depletion boundary-based ages and previous analyses that used nonrotating isochrones. Our methods do not provide a strong constraint on the metallicities of these clusters.