Constraints on the frequency of circumbinary planets in wide orbits

In the past decade, an increasing amount of effort has been spent on studying the formation and evolution of planets in the environment of binary host star systems (see e.g. the book “Planets in Binaries”, Haghighipour 2010). The Exoplanets.org database (Wright et al. 2011) lists several confirmed planets that have been found in binary systems to date. All of these discoveries have been made with indirect detection methods such as Doppler spectroscopy or transit photometry methods, which are heavily biased towards planets with short orbital periods and, therefore, favor circumstellar (‘s-type’) configurations around individual components of wide binary systems. Despite this bias, the Kepler spacecraft has discovered seven planets in circumbinary (‘p-type’) orbits encompassing tight binary systems, hinting at the existence of an extensive unseen population of circumbinary planets.Direct imaging, on the other hand, is a powerful planet detection technique particularly well suited to planets on wide orbits, which complements the limited parameter space of the indirect detection methods. However, such surveys have typically rejected binary systems from their target sample, leaving the population of wide-orbit planets in such systems largely unexplored. To address this, the SPOTS project (Search for Planets Orbiting Two Stars; Thalmann et al. 2014) is conducting the first dedicated direct imaging survey for circumbinary planets.In this talk I will present the results of a statistical analysis of the combined body of existing high contrast imaging constraints on circumbinary planets carried on to complement the results of our ongoing survey.