Abstract

About half of all stars reside in binary or higher multiplicity systems. Given the ubiquity of exoplanets demonstrated to us by the Kepler mission, one should naturally ask whether and how planets can form in stellar binary and multiple systems. In this talk I will provide an overview of the current observational status of planetary systems within and around binaries. I will then outline the key theoretical ideas about planet formation in binaries, focussing on the planetesimal fragmentation barrier (caused by the strong gravitational perturbations due to the companion) as a likely bottleneck for this process. Finally, I will present a possible resolution of this issue, which relies on the previously unrecognised role of the protoplanetary disk gravity for the planetary and planetesimal dynamics in binaries. I will argue that planets in binaries may hold important clues to planet formation in general.