Collaborative Research: Explaining the Orbits of Eccentric Warm Jupiters

The orbits of planetary systems hold clues about their origins. Gas giants like Jupiter are thought to form on circular orbits far from stars. However, exoplanets with large eccentricity abound, and the “hot Jupiter” class have orbital periods of just a few days. In some cases, extremely eccentric planets may approach their stars, where tidal forces deform them, dissipate energy, and ultimately circularize their orbits—a hypothesis known as high-eccentricity migration (HEM), which is the likely origin of many hot Jupiters. This project focuses on the physics of “warm Jupiters,” which orbit far enough from their stars to avoid strong tidal forces yet are too close to have formed in place, also suggesting a migratory origin. Their orbital properties inspire new projects that this team, from Indiana University and Northern Arizona University (NAU), is pursuing. They will provide research opportunities and training of new astronomers at both institutions, making project software publicly available, and hosting a new Spanish-language public lecture series at NAU. This work tackles a recent puzzle: the origin of eccentric warm Jupiters. One of the strongest pieces of evidence of HEM is the misaligned orbital planes of many hot Jupiters relative to the equator plane of their host stars, but eccentric warm Jupiters are typically aligned. To potentially explain this trend, this study pursues in-depth modeling of planetary systems: (a) coplanar high-eccentricity migration with a dynamical tidal treatment, (b) the influence of inertial waves on obliquity damping, and (c) the role of disk gaps in resonant capture and escape. Through gravitational interactions between planets, between planets and the disk, tidal energy dissipation, and population synthesis – this project uses the puzzle of warm Jupiters as a springboard to elucidate many issues in planetary dynamics. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.