Deserts and pile-ups in the distribution of exoplanets due to photoevaporative disc clearing

TL;DR

This paper models how EUV photoevaporation-driven disc clearing influences giant planet migration, creating observable deserts and pile-ups in exoplanet distributions, which can test theories of planet formation and disc evolution.

Contribution

It demonstrates that photoevaporative disc clearing significantly shapes the distribution of giant exoplanets, linking disc physics to observed planet arrangements.

Findings

Photoevaporation creates deserts and pile-ups in planet distributions.

The locations of features depend on planetary accretion efficiency.

Observations can test models of planet migration and disc clearing.

Abstract

We present models of giant planet migration in evolving protoplanetary discs. We show that disc clearing by EUV photoevaporation can have a strong effect on the distribution of giant planet semi-major axes. During disc clearing planet migration is slowed or accelerated in the region where photoevaporation opens a gap in the disc, resulting in "deserts" where few giant planets are found and corresponding "pile-ups" at smaller and larger radii. However, the precise locations and sizes of these features are strong functions of the efficiency of planetary accretion, and therefore also strongly dependent on planet mass. We suggest that photoevaporative disc clearing may be responsible for the pile-up of ~Jupiter-mass planets at ~1AU seen in exoplanet surveys, and show that observations of the distribution of exoplanet semi-major axes can be used to test models of both planet migration and disc clearing.