The stability of circumbinary planetesimal disks

Ground and space based observations in the past fifteen years have identified a new class of exoplanets. These systems have planets in orbit about the center of mass of a binary in p-type orbits. The formation of these p-type planets via accretion is intriguing from the perspective of planetesimal disk stability. The planetesimals exist in a planetesimal disk in orbit around a tight binary. The binary will cause gravitational perturbations to the disk potentially causing instability, hindering the accretion process. Thus, it is necessary for a circumbinary planetesimal disk to be stable. In this work, the predictor of stability for a circumbinary planetesimal disk will be Toomre’s stability criterion. Over 100 different cold circumbinary planetesimal disk configurations were simulated with Gadget2. Each simulation is inspected for local and global stability. In a circumbinary planetesimal disk there exists local stability regions at radii less than 10 AU. An instability regions exists between 12 AU and 27 AU. This intermediate region has stability parameters that increase with time, approaching stability and producing a globally stable disk. The global stabilization time for a circumbinary planetesimal disk is 105 ± 104 years.