Jupiter will become a hot Jupiter: Consequences of Post-Main-Sequence Stellar Evolution on Gas Giant Planets

TL;DR

This paper explores how gas giant planets like Jupiter will become hot Jupiters due to increased stellar irradiation during the Sun's red giant phase, affecting their atmospheres and wind patterns.

Contribution

It provides a detailed analysis of the atmospheric and wind changes in Jupiter-like planets as their host stars evolve into red giants, highlighting potential observational signatures.

Findings

Jupiter may become more highly irradiated than known hot Neptunes.

Post-main-sequence planets could accrete material, altering atmospheric chemistry.

Red-giant hot Jupiters likely have multiple narrow jets, unlike main-sequence counterparts.

Abstract

When the Sun ascends the red giant branch (RGB), its luminosity will increase and all the planets will receive much greater irradiation than they do now. Jupiter, in particular, might end up more highly irradiated than the hot Neptune GJ 436b and, hence, could appropriately be termed a "hot Jupiter." When their stars go through the RGB or asymptotic giant branch (AGB) stages, many of the currently known Jupiter-mass planets in several-AU orbits will receive levels of irradiation comparable to the hot Jupiters, which will transiently increase their atmospheric temperatures to ~1000 K or more. Furthermore, massive planets around post-main-sequence stars could accrete a non-negligible amount of material from the enhanced stellar winds, thereby significantly altering their atmospheric chemistry as well as causing a significant accretion luminosity during the epochs of most intense stellar mass loss. Future generations of infrared observatories might be able to probe the thermal and chemical structure of such hot Jupiters' atmospheres. Finally, we argue that, unlike their main-sequence analogs (whose zonal winds are thought to be organized in only a few broad, planetary-scale jets), red-giant hot Jupiters should have multiple, narrow jets of zonal winds and efficient day-night redistribution.