Energy optimization in extrasolar planetary systems: the transition from peas-in-a-pod to runaway growth
Abstract
Motivated by the trends found in the observed sample of extrasolar planets, this paper determines tidal equilibrium states for forming planetary systems – subject to conservation of angular momentum, constant total mass, and fixed orbital spacing. In the low mass limit, valid for super-Earth-class planets with masses of order mp ∼ 10 M⊕, previous work showed that energy optimization leads to nearly equal mass planets, with circular orbits confined to a plane. The present treatment generalizes previous results by including the self-gravity of the planetary bodies. For systems with a sufficiently large total mass $m_{\scriptstyle \rm T}$ in planets, the optimized energy state switches over from the case of nearly equal mass planets to a configuration where one planet contains most of the material. This transition occurs for a critical mass threshold of approximately $m_{\scriptstyle \rm T}\gtrsim m_{\scriptstyle \rm C}\sim 40\,{\rm M_\oplus}$ (where the value depends on the semimajor axes of the planetary orbits, the stellar mass, and other system properties). These considerations of energy optimization apply over a wide range of mass scales, from binary stars to planetary systems to the collection of moons orbiting the giant planets in our Solar system.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Mar 09, 2020
- Source ID
- 10.1093/mnras/staa624
Entities
People
- Anthony M. Bloch
- Fred C. Adams
- Gregory P. Laughlin
- Konstantin Batygin
Organizations
- Air Force Office of Scientific Research
- Alfred P. Sloan Foundation
- California Institute of Technology
- David and Lucile Packard Foundation
- National Science Foundation
- University of Michigan
- Yale University