CandY: Circumbinary And RockY

Planets orbiting both stars of a binary system -circumbinary planets- are challenging what we think we know about how exoplanets are assembled, and how their orbits subsequently evolve. Because they orbit one another, binary stars disturb the process of core accretion that creates planets. But, instead of changing the

number of planets created, the two stars instead affects circumbinary planets' masses and orbital separations, thus shining an unexpected light onto which planet formation processes are truly important. With its ambitious programme, CandY will consolidate circumbinary planets as an unavoidable corner of

exoplanetary science, crucial for the study of planet formation, and the study and interpretation of exoatmospheres. To better our understanding of planet formation, the CandY project will perform the first systematic study of circumbinary planets. CandY will develop a suite of new analytical methods, and conduct three ambitious

observing campaigns that will lead to the detection of dozens of new circumbinary planets, including some all way down to rocky masses. In parallel, the CandY team will study the atmospheric composition of circumbinary planets for the very first time in order to reveal yet more clues about these exotic worlds.

During the CandY project, we will record every similarity, and any difference between the population of circumbinary planets and the population of exoplanets orbiting single stars. This systematic exercise will create a leap in our understanding about how planets are produced and which processes dominate planet

assembly and their subsequent orbital migration. In addition, circumbinary planets have unique orbital properties amongst exoplanets. Their orbital dynamics boost their probability to experience transits easing exo-atmospheric investigations. Moreover, circumbinary exoplanets are the only transiting planets for which seasonal atmospheric variations can be studied.