Super-Eccentric Migrating Jupiters

TL;DR

This paper discusses the role of super-eccentric migrating Jupiters in hot Jupiter formation, predicting their detectable population and providing a test for high-eccentricity migration theories.

Contribution

It introduces a theoretical framework linking super-eccentric Jupiters to hot Jupiter formation and predicts their observable distribution for Kepler to test migration scenarios.

Findings

Super-eccentric Jupiters should be detectable by Kepler if they are common progenitors.

The number distribution of these planets follows a specific a^0.5 relation.

Detection of such planets would support high-eccentricity migration models.

Abstract

An important class of formation theories for hot Jupiters involves the excitation of extreme orbital eccentricity (e=0.99 or even larger) followed by tidal dissipation at periastron passage that eventually circularizes the planetary orbit at a period less than 10 days. In a steady state, this mechanism requires the existence of a significant population of super-eccentric (e>0.9) migrating Jupiters with long orbital periods and periastron distances of only a few stellar radii. For these super-eccentric planets, the periastron is fixed due to conservation of orbital angular momentum and the energy dissipated per orbit is constant, implying that the rate of change in semi-major axis a is \dot a \propto a^0.5 and consequently the number distribution satisfies dN/dlog a\propto a^0.5. If this formation process produces most hot Jupiters, Kepler should detect several super-eccentric migrating progenitors of hot Jupiters, allowing for a test of high-eccentricity migration scenarios.