In-Situ Scattering of Warm Jupiters and Implications for Dynamical Histories

• Published in: arXiv.org 2019-11
• Main Authors: Anderson, Kassandra R, Lai, Dong, Bonan Pu
• Format: Article
• Language: English
• Subjects: Collisions; Eccentricity; Ejection; Extrasolar planets; Gas giant planets; Jupiter; Migration; Orbits; Planets; Scattering; Survival
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.1908.04300

Many warm Jupiters (WJs) have substantial eccentricities, which are linked to their formation and migration histories. This paper explores eccentricity excitation of WJs due to planet-planet scattering, beginning with 3-4 planets in unstable orbits, with the innermost planet placed in the range (0.1 - 1)AU. Such a setup is consistent with either in-situ formation or arrival at sub-AU orbits due to disk migration. Most previous N-body experiments have focused on "cold" Jupiters at several AU, where scattering results in planet ejections, efficiently exciting the eccentricities of surviving planets. In contrast, scattering at sub-AU distances results in a mixture of collisions and ejections, and the final eccentricities of surviving planets are unclear. We conduct scattering experiments for a range of planet masses and initial spacings, including the effect of general relativistic apsidal precession, and systematically catalogue the scattering outcomes and properties of surviving planets. A comparable number of one-planet and two-planet systems are produced. Two-planet systems arise exclusively through planet-planet collisions, and tend to have low eccentricities/mutual inclinations and compact configurations. One-planet systems arise through a combination of ejections and collisions, resulting in higher eccentricities. The observed eccentricity distribution of solitary WJs (lacking detection of a giant planet companion) is consistent with roughly 60% of the systems having undergone in-situ scattering, and the remaining experiencing a quiescent history.