Evolution of Exoplanets and their Parent Stars

TL;DR

This paper reviews the evolution, composition, and formation of exoplanets, especially giant gaseous ones, highlighting how their properties relate to their host stars and the implications for planetary development.

Contribution

It provides a comprehensive review of exoplanet evolution, linking planetary characteristics with stellar properties and emphasizing the role of accretion and stellar dissipation in planetary formation.

Findings

Giant exoplanets have large radii due to hydrogen-helium envelopes.

Planetary heavy element content correlates with stellar metallicity.

Distribution of massive planets varies with host star type.

Abstract

Studying exoplanets with their parent stars is crucial to understand their population, formation and history. We review some of the key questions regarding their evolution with particular emphasis on giant gaseous exoplanets orbiting close to solar-type stars. For masses above that of Saturn, transiting exoplanets have large radii indicative of the presence of a massive hydrogen-helium envelope. Theoretical models show that this envelope progressively cools and contracts with a rate of energy loss inversely proportional to the planetary age. The combined measurement of planetary mass, radius and a constraint on the (stellar) age enables a global determination of the amount of heavy elements present in the planet interior. The comparison with stellar metallicity shows a correlation between the two, indicating that accretion played a crucial role in the formation of planets. The dynamical evolution of exoplanets also depends on the properties of the central star. We show that the lack of massive giant planets and brown dwarfs in close orbit around G-dwarfs and their presence around F-dwarfs are probably tied to the different properties of dissipation in the stellar interiors. Both the evolution and the composition of stars and planets are intimately linked.