Circumbinary planet and gas dynamics

Diego Munoz (Cornell)

October 29, 2015

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Abstract: One of the puzzles of circumbinary planets is that none of the stellar binaries currently known to host planets has a period shorter than 7 days, despite the large number of eclipsing binaries found in the Kepler target list with periods shorter than a few days. These compact binaries are believed to have evolved from wider orbits into their current configurations via the so-called Lidov- Kozai migration mechanism, in which gravitational perturbations from a distant tertiary companion induce large-amplitude eccentricity oscillations in the binary, followed by orbital decay and circularization due to tidal dissipation in the stars. I will show results of the orbital evolution of planets around binaries undergoing orbital decay and show that planets subject to this dramatic change in orbital configuration have chances of surviving. Another puzzle, still unresolved, is that of the origin of the planet-hosting binaries themselves, including their poorly understood accretion history during the circumbinary disk stage. I will discuss new results from numerical simulations using moving-mesh hydrodynamics, in which accretion onto the individual stars can be directly computed, showing an interplay between binary eccentricity, disk eccentricity and accretion rates.