Planet Formation in Binaries - Planetary Exploration and Science: Recent Results and Advances - page 304

13.2 Observational Constraints: Planets in Binaries

Exoplanet search surveys were initially strongly biased against binary systems of
separation

200 AU (Eggenberger and Udry 2010 ), in great part because these
searches were focusing on stellar environments as similar as possible to the solar
system. In 2003, however, the first exoplanet in a close binary was detected in
the Cephei system (Hatzes et al. 2003 ), and today more than 60 exoplanets are
known to inhabit multiple star systems (Roell et al. 2012 ). Note that, in many cases,
these exoplanets were detected before the presence of a stellar companion was later
established by imaging campaigns (Mugrauer and Neuhäuser 2009 ). As a result,
for most of these systems, the separation of the binary is indeed relatively large,
often in excess of 500 AU (Roell et al. 2012 ). However, 10 of these planet-bearing
binaries have a separation of less than 100 AU, with 5 exoplanets in close binaries
with separations of 20 AU (Fig. 13.1 ): Gl86 (Queloz et al. 2000 ; Lagrange et al.

Fig. 13.1 1,000 AU

(as of July 2013). Companion stars are displayed as yellow circles , whose radius is proportional to
.M 2 =M 1 / 1=3 . Planets are marked as blue circles whose radius is proportional to .m pl =m J u p / 1=3 .
The horizontal lines represent the radial excursion of the planets' and stars' orbits (when they are
known). For most binaries of separation

Architecture of all circumprimary planet-bearing binaries with separation

100 AU, the orbit is not known and the displayed value
corresponds to the projected current separation. The short horizontal lines correspond to the outer
limit of the orbital stability region around the primary, as estimated by Holman and Wiegert ( 1999 )