Dynamical Evolution and Migration of Circumbinary Planets and Their Habitability

The recent success of the Kepler space telescope in detecting several circumbinary planets has raised many questions on the formation, evolution, and habitability of these objects. The detection of multiple transists in these systems points to the co-planarity of the orbital planes of the binary and planet(s), giving strong support to the idea that these planets formed in circumbinary protoplanetary disks. The proximity of some of these planets to the boundary of orbital instability around the binary suggests an evolutionary scenario in which planets form at larger distances and migrate to their present orbits. How such planets form, and how the binarity of the system affects their formation and subsequent migration are among fundamental questions that require deep understanding of the growth and evolution of solid objects in circumbinary environments, and their dynamical evolution. Given that several of the currently known circumbinary planets are in the habitable zone, the habitability of planet-hosting binary systems has also become an important topic of research. We have carried out extensive analysis of the dynamical evolution of planets in a circumbinary disk, and their habitability. The results of our hydrodynamical simulations indicate that planets migrate inward and settle near the inner edge of the circumbinary disk (the stability limit), in good agreement with the results of the observations. Our model of habitability takes into account, self-consistently, the contribution of each star to the total flux received at the top of the planet's atmosphere, producing accurate maps of the HZ of the system. We present the results of our studies and discuss their applications to the formation and habitability of the currently known Kepler circumbinary planets.