Planetary eccentricity-period (PEP) distributions

We first divided the sample into low- and high-mass exoplanet subsamples based on the distribution of the (minimum) planetary masses, which displays a clear two-Gaussian distribution, separated at 0.165M_J_. We then selected 216 orbits, low- and high-mass alike, with eccentricities significantly distinct from circular orbits.

The 131 giant-planet eccentric orbits display a clear upper envelope, which we model quantitatively, rises monotonically from zero eccentricity and reaches an eccentricity of 0.8 at P~100 days. Conversely, the 85 low-mass planetary orbits display a flat eccentricity distribution between 0.1 and 0.5, with almost no dependence on the orbital period. We show that the striking difference between the two PEP distributions is not a result of the detection technique used.