Re-crowning The Queen: Membership, Age, and Rotation Periods for the Open Cluster Coma Berenices

Abstract Coma Berenices (Coma Ber), an open cluster about the same age as Praesepe and Hyades (700–800 Myr) is, despite being only 85 pc away, less well studied than its famous cousins. This is due principally to sparseness low proper motion, which together made Ber’s membership challenging establish pre-Gaia. We have curated a new list of members based on Gaia DR2 astrometry, derived metallicity interstellar reddening using LAMOST data, inferred cluster’s by fitting PARSEC isochrones color–magnitude diagram. then measured rotation periods for low-mass TESS ZTF photometry. Our isochrone TESS- ZTF-derived confirm that Ber coeval with Praesepe. work first step toward re-establishing another valuable benchmark age–rotation–activity studies.