Exoplanet parameters from Kepler and K2

Applying completeness corrections clearly reveals the radius valley in the maximum a posteriori occurrence rates as a function of orbital separation and planet radius. We measure the slope of the valley to be r_p,valley_{prop}F^-0.060{+/-}0.025^, which bears the opposite sign from that measured around Sun-like stars, thus suggesting that thermally driven atmospheric mass loss may not dominate the evolution of planets in the low stellar mass regime or that we are witnessing the emergence of a separate channel of planet formation.

The latter notion is supported by the relative occurrence of rocky to non-rocky planets increasing from 0.5{+/-}0.1 around mid-K dwarfs to 8.5{+/-}4.6 around mid-M dwarfs. Furthermore, the center of the radius valley at 1.54{+/-}0.16R{earth} is shown to shift to smaller sizes with decreasing stellar mass, in agreement with physical models of photoevaporation, core-powered mass loss, and gas-poor formation. Although current measurements are insufficient to robustly identify the dominant formation pathway of the radius valley, such inferences may be obtained by the Transiting Exoplanet Survey Satellite with O(85000) mid-to-late M dwarfs observed with 2minutes cadence.