Planet Formation in Binaries - Planetary Exploration and Science: Recent Results and Advances - page 302

Chapter 13
Planet Formation in Binaries

P. Thebault and N. Haghighipour

Abstract Spurred by the discovery of more than 60 exoplanets in multiple systems,
binaries have become in recent years one of the main topics in planet-formation
research. Numerous studies have investigated to what extent the presence of
a stellar companion can affect the planet-formation process. Such studies have
implications that can reach beyond the sole context of binaries, as they allow to
test certain aspects of the planet-formation scenario by submitting them to extreme
environments. We review here the current understanding on this complex problem.
We show in particular how each of the different stages of the planet-formation
process is affected differently by binary perturbations. We focus especially on the
intermediate stage of kilometre-sized planetesimal accretion, which has proven to
be the most sensitive to binarity and for which the presence of some exoplanets
observed in tight binaries is difficult to explain by in situ formation following
the “standard” planet-formation scenario. Some tentative solutions to this apparent
paradox are presented. The last part of our review presents a thorough description
of the problem of planet habitability, for which the binary environment creates a
complex situation because of the presence of two irradiation sources of varying
distance.

Keywords Planetary systems ￿ Binary stars

13.1 Introduction

About half of solar-type stars reside in multiple stellar systems (Raghavan et al.
2010 ). As a consequence, one of the most generic environments to be considered
for studying planet formation should in principle be that of a binary. However, the