Evolutionary Timescales On M Dwarf Planets From Dynamical Stability Arguments

The diversity of dynamical conditions among exoplanets is now well established. The overlap between typical dynamical timescales and (potential) evolutionary timescales is as-yet not well understood. We employ an agnostic approach to constraining the dynamical timescales relevant to M dwarf planetary systems, requiring only that dynamical sculpting (if it occurs) reproduces observed demographics today. Based on limiting cases for these timescales, we explore the potential effect of dynamical sculpting on evolutionary conditions. Changes in eccentricity and mutual inclination may alter the conditions on the surface of a planet, with life on Earth showing varying robustness to dramatic environmental changes. With a suite of simulations, we assign dynamical stability states to synthetic planetary systems according to the age of the star (varying the disruption rate within allowable limits that are consistent with the present-day sample). We simulate the resulting detection yield of planets, according to the sensitivity of NASA’s Kepler and TESS missions. We find that multi-transiting systems are predicted to have, on average, longer uninterrupted evolutionary timescales than single-transiting systems. The degree of this effect is different among the Kepler and TESS samples. These results may inform the selection of targets for atmospheric follow-up studies by telescopes such as JWST.