Аннотация
Almost half of the stellar systems in the solar neighborhood are made up of
multiple stars. In multiple-star systems, planet formation is under the
dynamical influence of stellar companions, and the planet occurrence rate is
expected to be different from that for single stars. There have been numerous
studies on the planet occurrence rate of single star systems. However, to fully
understand planet formation, the planet occurrence rate in multiple-star
systems needs to be addressed. In this work, we infer the planet occurrence
rate in multiple-star systems by measuring the stellar multiplicity rate for
planet host stars. For a sub-sample of 56 $Kepler$ planet host stars, we use
adaptive optics (AO) imaging and the radial velocity (RV) technique to search
for stellar companions. The combination of these two techniques results in high
search completeness for stellar companions. We detect 59 visual stellar
companions to 25 planet host stars with AO data. Three stellar companions are
within 2$^\prime\prime$, and 27 within 6$^\prime\prime$. We also detect 2
possible stellar companions (KOI 5 and KOI 69) showing long-term RV
acceleration. After correcting for a bias against planet detection in
multiple-star systems due to flux contamination, we find that planet formation
is suppressed in multiple-star systems with separations smaller than 1500 AU.
Specifically, we find that compared to single star systems, planets in
multiple-star systems occur $4.5\pm3.2$, $2.6\pm1.0$, and $1.7\pm0.5$ times
less frequently when a stellar companion is present at a distance of 10, 100,
and 1000 AU, respectively. This conclusion applies only to circumstellar
planets; the planet occurrence rate for circumbinary planets requires further
investigation.
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