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October 17th, 2014: How to Flip a Binary Without a Spatula — Tales of Hierarchical Three-body Systems

Posted on Sep 23, 2014 in Seminars

Gongjie Li (Harvard-Smithsonsian Center for Astrophysics)

The secular dynamical evolution of a hierarchical three body system, in which a distant third object orbits around a binary has been studied extensively, demonstrating that the inner orbit can undergo large eccentricity and inclination oscillations. It had been shown before that starting with a circular inner orbit, large mutual inclination (40 – 140 degree) can produce long timescale modulations that drive the eccentricity to extremely large values and can flip the orbit. Here, we demonstrate that starting with an almost coplanar configuration, for eccentric inner and outer orbits, the eccentricity of the inner orbit can still be excited to high values, and the orbit can flip by ~180 degree, rolling over its major axis. The ~180 degree flip criterion and the flip timescale are described by simple analytic expressions that depend on the initial orbital parameters. With tidal dissipation, this mechanism can produce counter-orbiting exo-planetary systems. In addition, we also show that this mechanism has the potential to change the stellar distribution for binary black hole systems. Furthermore, we explore the entire eccentricity and inclination parameter space to identify the underlying resonances, the chaotic regions and the regions that can excite the eccentricity and flip the orbit.