Origins of Hot Jupiters

TL;DR

Hot Jupiters are close-in exoplanets whose origins are debated, with in situ formation, disk migration, and high eccentricity tidal migration as main hypotheses, and current evidence suggests multiple channels contribute.

Contribution

This paper reviews and synthesizes the three main hypotheses for hot Jupiter formation, highlighting that a combination of channels likely explains their properties.

Findings

No single origin channel explains all observations.

Two major formation channels together account for hot Jupiter properties.

Current evidence supports multiple formation pathways.

Abstract

Hot Jupiters were the first exoplanets to be discovered around main sequence stars and astonished us with their close-in orbits. They are a prime example of how exoplanets have challenged our textbook, solar-system inspired story of how planetary systems form and evolve. More than twenty years after the discovery of the first hot Jupiter, there is no consensus on their predominant origin channel. Three classes of hot Jupiter creation hypotheses have been proposed: in situ formation, disk migration, and high eccentricity tidal migration. Although no origin channel alone satisfactorily explains all the evidence, two major origins channels together plausibly account for properties of hot Jupiters themselves and their connections to other exoplanet populations.