BEBOP · Binaries Escorted By Orbiting Planets

Planets orbiting both stars of a binary system -circumbinary planets- are challenging our understanding about how planets assemble, and how their orbits subsequently evolve. Long confined to science-fiction, circumbinary planets were confirmed by the Kepler spacecraft, in one of its most spectacular, and impactful result. Despite Kepler’s insights, a lot remains unknown about these planets. Kepler also suffered from intractable biases that the BEBOP project will solve.BEBOP will revolutionise how we detect and study circumbinary planets. Conducting a Doppler survey, we will vastly improve the efficiency of circumbinary planet detection, and remove Kepler’s biases. BEBOP will construct a clearer picture of the circumbinary planet population, and free us from the inherent vagaries, and important costs of space-funding. Thanks to the Doppler method we will study dynamical effects unique to circumbinary planets, estimate their multiplicity, and compute their true occurrence rate.Circumbinary planets are essential objects. Binaries disturbe planet formation. Any similarity, and any difference between the population of circumbinary planets and planets orbiting single stars, will bring novel information about how planets are produced. In addition, circumbinary planets have unique orbital properties that boost their probability to experience transits. BEBOP’s detections will open the door to atmospheric studies of colder worlds than presently available.Based on already discovered systems, and on two successful proofs-of-concept, the BEBOP team will detect 15 circumbinary gas-giants, three times more than Kepler. BEBOP will provide an unambiguous measure of the efficiency of gas-giant formation in circumbinary environments. In addition the BEBOP project comes with an ambitious programme to combine three detection methods (Doppler, transits, and astrometry) in a holistic approach that will bolster investigations into circumbinary planets, and create a lasting legacy.