Implications of the TTV-detection of close-in terrestrial planets around M stars for their origin and dynamical evolution

Abstract

It has been shown that an Earth-size planet or a super-Earth, in resonance with a transiting Jupiter-like body around an M star, can create detectable TTV signals (Kirste & Haghighipour, 2011). Given the low masses of M stars and their circumstellar disks, it is expected that the transiting giant planet to have formed at large distances and migrated to its close-in orbit. That implies, the terrestrial planet has to form during the migration of the giant planet, be captured in resonances, and migrate with the giant body to short-period orbits. To determine the possibility of this scenario, we have studied the dynamics of a disk of protoplanetary embryos and the formation of terrestrial planets during the migration of a Jupiter-like planet around an M star. Results suggest that unless the terrestrial planet was also formed at large distances and carried to its close-in resonant orbit by the giant planet, it is unlikely for this object to form in small orbits. We present the details of our simulations and discuss the implication of the results for the origin of the terrestrial planet.