We present a uniform analysis of the atmospheric escape rate of Neptune-like planets with estimated radius and mass (restricted to M_p_<30M_{Earth}). For each planet, we compute the restricted Jeans escape parameter, {Lambda}, for a hydrogen atom evaluated at the planetary mass, radius, and equilibrium temperature. Values of {Lambda}0.1M{Earth}_/Gyr), well in excess of the energy-limited mass-loss rates. This constitutes a contradiction, since the hydrogen envelopes cannot be retained given the high mass-loss rates. We hypothesize that these planets are not truly under such high mass-loss rates. Instead, either hydrodynamic models overestimate the mass-loss rates, transit-timing-variation measurements underestimate the planetary masses, optical transit observations overestimate the planetary radii (due to high-altitude clouds), or Neptunes have consistently higher albedos than Jupiter planets. We conclude that at least one of these established estimations/techniques is consistently producing biased values for Neptune planets. Such an important fraction of exoplanets with misinterpreted parameters can significantly bias our view of populations studies, like the observed mass-radius distribution of exoplanets for example.

Cone search capability for table J/MNRAS/466/1868/tablea1 (*Observed and derived parameters for the sub-Neptune planet sample.)