Vol. 533
In section 10. Planets and planetary systems

Formation and evolution of planetary systems in presence of highly inclined stellar perturbers

by K. Batygin, A. Morbidelli, and K. Tsiganis, A&A 533, A7


For planets in binary systems, the presence of an inclined distant companion can lead to a rise in the inclination and eccentricity of the planetary orbit through the so-called Kozai mechanism. While this appears to explain at least a fraction of the systems known today, this mechanism also poses a threat to any formation of these planets: Planetesimals subject to the same Kozai process would encounter one another at high velocities and destroy themselves, turning into dust rather than accrete to form a planet. Batygin et al. have found a solution to this problem. When the disk of planetesimals is of sufficient mass compared to that of the binary companion and its orbital distance (see figure), its self-gravity dominates the apsidal precession induced by the companion. Planets are thus able to form even in the presence of a perturbing stellar companion, as long as the protoplanetary disk from which they are born is massive enough.