Probing the impact of stellar duplicity on the frequency of giant planets: final results of our VLT/NACO survey

TL;DR

This study investigates how the presence of moderately close stellar companions influences the frequency of giant planets around solar-type stars, using VLT/NACO adaptive optics observations of 130 nearby stars.

Contribution

It provides the final results of a systematic survey testing for stellar companions and their impact on giant planet occurrence in binary systems with separations of 35-100 AU.

Findings

Giant planets are slightly less frequent in binaries with 35-100 AU separation.

Confirmed physical companions for two candidate stars.

Many candidate companions are unbound, indicating no physical association.

Abstract

If it is commonly agreed that the presence of a (moderately) close stellar companion affects the formation and the dynamical evolution of giant planets, the frequency of giant planets residing in binary systems separated by less than 100 AU is unknown. To address this issue, we have conducted with VLT/NACO a systematic adaptive optics search for moderately close stellar companions to 130 nearby solar-type stars. According to the data from Doppler surveys, half of our targets host at least one planetary companion, while the other half show no evidence for short-period giant planets. We present here the final results of our survey, which include a new series of second-epoch measurements to test for common proper motion. The new observations confirm the physical association of two companion candidates and prove the unbound status of many others. These results strengthen our former conclusion that circumstellar giant planets are slightly less frequent in binaries with mean semimajor axes between 35 and 100 AU than in wider systems or around single stars.