Exoplanet Radius Gap Dependence on Host Star Type

TL;DR

This paper investigates how the observed exoplanet radius gap at around 2 Earth radii varies depending on the type of host star, using Kepler data and stellar spectroscopy.

Contribution

It extends previous analysis by examining the dependence of the exoplanet radius gap on host star spectral type.

Findings

The radius gap varies with host star type.

Host star properties influence planet size distribution.

Results suggest different formation or evolution processes based on star type.

Abstract

Exoplanets smaller than Neptune are numerous, but the nature of the planet populations in the 1-4 Earth radii range remains a mystery. The complete Kepler sample of Q1-Q17 exoplanet candidates shows a radius gap at ~ 2 Earth radii, as reported by us in January 2017 in LPSC conference abstract #1576 (Zeng et al. 2017). A careful analysis of Kepler host stars spectroscopy by the CKS survey allowed Fulton et al. (2017) in March 2017 to unambiguously show this radius gap. The cause of this gap is still under discussion (Ginzburg et al. 2017; Lehmer & Catling 2017; Owen & Wu 2017). Here we add to our original analysis the dependence of the radius gap on host star type.