Benjamin Liberles

Understanding the origin of the enhanced occurrence of compact systems of multiple small exoplanets around metal-poor stars in the planet formation process is a topic of ongoing research. Here we consider the radii of planets residing in systems of multiple-transiting planets, compared to those residing in single-transiting systems, with a particular focus on late-type host stars. We find statistical evidence (p < 0.0026) that planets in compact multiple systems are larger, on average, than their single-transiting counterparts for planets with Rp < 6 R⊕. We determine that the offset cannot be explained by detection bias. We investigate whether this effect could be explained via more efficient outgassing of a secondary atmosphere in compact multiple systems due to the stress and strain forces of interplanetary tides on planetary interiors. We find that this effect is insufficient to explain our observations without significant enrichment in H2O compared to Earth-like bulk composition.