How Distant Binary Stars Reshape Their Planetary Systems

Although ~1/3 of all known planet-hosting binary stars are very wide (average stellar separations beyond 1000 AU), there are very few dynamical studies that consider planetary systems within such binaries.  Contrary to previous assumptions, we show that many of these distant binaries will have dramatic impacts on resident planetary systems.  Because distant binary orbits are so weakly bound by gravity, perturbations from the Milky Way’s tide and other passing stars drive these orbits through brief phases of very high eccentricity. During such phases, close approaches between the two companion stars occur and can deliver severe perturbations to planets residing within the system.  These perturbations can greatly alter the spin-orbit angle of planetary systems (the angle between the stellar spin axis and the planetary orbital plane).  In addition, major dynamical instabilities can be induced in planetary systems, resulting in planet-planet scattering and very excited eccentricities of the surviving planetary orbits.  We consider observational signatures of both of these effects and whether they exist currently. Furthermore, we show that such systems may provide new information about the general properties of all planetary systems.

MP 134

Nathan Kaib (Queen's University)

June 06, 2012
11:00 - 12:00