Rotating Stars from Kepler Observed with Gaia DR1

Abstract: Astrometric data from the recent Gaia Data Release 1 has been matched against the sample of stars from Kepler with known rotation periods. A total of 1,299 bright rotating stars were recovered from the subset of Gaia sources with good astrometric solutions, most with temperatures hotter than 5000 K. From these sources, 894 were selected as lying near the main sequence using their absolute G-band magnitudes. These main sequence stars show a bimodality in their rotation period distribution, centered roughly around a 600 Myr rotation-isochrone. This feature matches the bimodal period distribution found in cooler stars with Kepler, but was previously undetected for solar-type stars due to sample contamination by subgiants. A tenuous connection between the rotation period and total proper motion is found, suggesting the period bimodality is due to the age distribution of stars within ~300pc of the Sun, rather than a phase of rapid angular momentum loss. This work emphasizes the unique power for understanding stellar populations by combining temporal monitoring from Kepler with astrometric data from Gaia.