Resonant and ultra-short-period planet systems

This evolution is impossible to directly observe on human timescales in most individual systems. While the availability of accurate and precise age inferences for individual exoplanet host stars with ages {tau} in the interval 1Gyr<~{tau}<~10Gyr would constrain this evolution, accurate and precise age inferences are difficult to obtain for isolated field dwarfs like the host stars of most exoplanets.

The Galactic velocity dispersion of a thin-disk stellar population monotonically grows with time, and the relationship between age and velocity dispersion in a given Galactic location can be calibrated by a stellar population for which accurate and precise age inferences are possible. Using a sample of subgiants with precise age inferences, we calibrate the age-velocity dispersion relation in the Kepler field. Applying this relation to the Kepler field's planet populations, we find that Kepler-discovered systems plausibly in second-order mean-motion resonances have 1Gyr<~{tau}<~2Gyr.