Revised Radii of Kepler Stars and Planets Using Gaia Data Release 2

Understand

One bottleneck for the exploitation of data from the $Kepler$ mission for stellar astrophysics and exoplanet research has been the lack of precise radii and evolutionary states for most of the observed stars.

• We report revised radii of 177,911 $Kepler$ stars derived by combining parallaxes from $Gaia$ Data Release 2 with the DR25 $Kepler$ Stellar Properties Catalog.
• The median radius precision is $\approx$ 8%, a typical improvement by a factor of 4-5 over previous estimates for typical $Kepler$ stars.
• We find that $\approx$ 67% ($\approx$ 120,000) of all $Kepler$ targets are main-sequence stars, $\approx$ 21% ($\approx$ 37,000) are subgiants, and $\approx$ 12% ($\approx$ 21,000) are red giants, demonstrating that subgiant contamination is less severe than some previous estimates and that Kepler targets are mostly main-sequence stars.