A sub-Saturn mass-radius desert for planets with equilibrium temperature

Abstract

The sample of exoplanets from the NASA Exoplanet Archive with equilibrium temperature ≤ 600 K and with low uncertainty for both mass and radius measurements is found to have a desert in the mass-radius distribution consistent with predictions from the core-accretion scenario. This sub-Saturn mass-radius desert is almost completely barren of any planets with both a mass > 20 M⊕ and a radius in the range 4.0–7.5 R⊕ for the sample of planets with Teq ≤ 600 K. In contrast, the sample of planets with Teq > 630 K includes a large fraction of planets with mass-radius values that fall into the Teq ≤ 600 K sub-Saturn mass-radius desert. The difference between the two populations may result from differences in migration history in the core-accretion scenario.