1. The Evolution of Eccentric Hot Jupiters Due to Roche Lobe Overflow at Periastron
- Author
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Salmon, Rachel, Salmon, Rachel, Salmon, Rachel, and Salmon, Rachel
- Abstract
As the number of exoplanets and planet candidates increases, so does the number of systems that look strikingly different from our own. These exotic systems display a wide variation in many characteristics including planet mass, star mass, planet radius, and planet distance from the parent star. One exotic system of particular interest is the hot Jupiter system. It is characterized by a Jupiter mass planet with a close-in orbit. Because of the proximity of the planet to its parent star, we would expect these systems to be tidally circularized. However, astronomers observe many systems with significant eccentricities, suggesting that a mechanism must exist to account for sustained eccentric orbits. Previous theoretical analyses found that, in a population of eccentric hot Jupiters generated by planet-planet scattering, a significant fraction will overfill their Roche lobe at periastron. Other work has noted that mass loss in systems similar to hot Jupiters can act to increase the eccentricity of the orbit of a binary system. Here, we consider the effects of tidal circularization and mass loss on the orbital evolution of the hot Jupiters. By analyzing the balance between the tidal circularization and mass loss, we can determine an equilibrium eccentricity as a function of planet mass and the efficiency of the tides at redistributing angular momentum. If such an equilibrium value exists, then it is possible for this mechanism to be responsible for the sustained eccentric orbits of hot Jupiters that we observe. We present the orbital parameters for these equilibrium orbits over a broad parameter space and compare those results to the current population of observed extrasolar planets.
- Published
- 2015