Dynamical origin of S-type planets in close binary stars
  Understanding the origin of planets that have formed in binary stars is
fundamental to constrain theories of binary and planet formation. The planet
occurrence rate in binaries with a separation $\lesssim 50$ AU is only $\sim$
one third that of wider binaries or single stars. This may indicate that a
close companion has a ruinous influence on planet formation, because it can
truncate the protoplanetary disc and pump up planetesimals eccentricity and
collision probability. Nevertheless, observations have revealed a few of these
systems, which challenge current planet formation theories. Dynamical
interactions can deliver planets into S-type orbits. In this paper, we consider
as a possible scenario for forming S-type planets in close binaries the single
star-binary star interactions that commonly take place in star clusters. We
find that the final fraction and orbital properties of S-type planets in close
binaries are mainly determined by the mass ratio of the stars involved in the
close encounter, and the initial binary and planet semi-major axes. Present and
upcoming missions, as TESS, PLATO and CHEOPS may shed new light on the origin
of S-type planets in close binaries.
