Zusammenfassung
Recent surveys indicate that planets in binary systems are more abundant than
previously thought, which is in agreement with theoretical work on disc
dynamics and planet formation in binaries. In order to measure the abundance
and physical characteristics of wide-orbit giant exoplanets in binary systems,
we have designed the 'VIsual Binary Exoplanet survey with Sphere' (VIBES) to
search for planets in visual binaries. It uses the SPHERE instrument at VLT to
search for planets in 23 visual binary and four visual triple systems with ages
of <145 Myr and distances of <150 pc. We used the IRDIS dual-band imager on
SPHERE to acquire high-contrast images of the sample targets. For each binary,
the two components were observed at the same time with a coronagraph masking
only the primary star. For the triple star, the tight components were treated
as a single star for data reduction. This enabled us to effectively search for
companions around 50 individual stars in binaries and four binaries in triples.
We derived upper limits of $<$13.7\% for the frequency of sub-stellar
companions around primaries in visual binaries, $<$26.5\% for the fraction of
sub-stellar companions around secondaries in visual binaries, and an occurrence
rate of $<$9.0\% for giant planets and brown dwarfs around either component of
visual binaries. We have combined our observations with literature measurements
to astrometrically confirm, for the first time, that 20 binaries and two triple
systems, which were previously known, are indeed physically bound. Finally, we
discovered a third component of the binary HD~121336. The upper limits we
derived are compatible with planet formation through the core accretion and the
gravitational instability processes in binaries. These limits are also in line
with limits found for single star and circumbinary planet search surveys.
Nutzer