Origin Of Hot & Warm Jupiters From Enhanced High Eccentricity Migration

Hot Jupiters are gas giants orbiting their host stars with an orbital period ≲10 days, warm Jupiters have periods ranging between 10 days and 100 days. Explaining the origin of hot and warm Jupiters sets a great challenge to the current planet formation theories. In situ formation is problematic due to deficiency of materials close to the host star, hence hot and warm Jupiters candidates are assumed to migrate from their initial formation location.Nevertheless, current theories predict much long formation timescales which implies lower fractions of hot and warm Jupiters than observations indicate.

A possible formation channel is high eccentricity migration, induced by tidal forces. The resulting timescales depend strongly on the radius of the migrating planet, dictated from the initial core accretion phase.Hot and warm Jupiters contract within a Kelvin-Helmholtz timescales to their current observed radii. Thus, while the observed radii of current hot Jupiters are ~1–2.5 R_J, and ~1 R_J for warm Jupiters, their initial radii, once the core accretion phase ended, might exceed these values.

Here we suggest an enhanced high eccentricity migration, induced by initially inflated hot and warm Jupiters candidates. We couple the internal evolution of the planet with its orbital evolution around its host, which are affected by tidal dissipation, tidal heating and irradiation.We show that external energy sources might play a role in maintaining large radii during the migration, shortening even more the migration timescales.We conclude that our model suggests an intense formation channel of hot and warm Jupiters, that produces hot Jupiters within timescales shorter by an order of magnitude or more from the initially non-inflated hot Jupiters, and eccentric warm Jupiter within Hubble time.