Presentation #124.01 in the session “Stellar Rotation, Variability, and Flares”.
Coma Bernices (Coma Ber), an open cluster thought to be about the same age as the Hyades (~800 Myr) and not much farther away, is far less well studied than its famous cousin. This is due principally to its sparseness and low proper motion, which together made Coma Ber’s membership challenging to establish pre-Gaia. We have curated a new list of its members based on Gaia DR2 astrometry, derived the cluster’s metallicity and interstellar reddening using Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) data, and inferred its age by fitting PAdova and TRieste Stellar Evolution Code (PARSEC) isochrones to its color-magnitude diagram. We then measured rotation periods for Coma Ber’s low-mass members using time-series photometry from the Transiting Exoplanet Survey Satellite (TESS). Our isochrone fitting and the TESS-derived rotation periods confirm that Coma Ber is coeval with the Hyades and Praesepe. However, its metallicity is about 0.2 dex lower than these two benchmark clusters, allowing us to investigate the impact of metallicity on the age-rotation relation for low-mass stars.