Planet formation and stability in polar circumbinary discs

GIUPPONE, CRISTIAN; CUELLO, NICOLAS

Cordoba

Workshop; FOF 2019 Meeting; 2019

Observatorio Astronómico de Córdoba - IATE

Dynamical studies suggest that most of the circumbinary discs (CBDs) should be coplanar, i.e. the rotation vectors of the binary and the disc are aligned. Additionally, some theoretical works show that under certain conditions a CBD can become polar, which means that its rotation vector is orthogonal with respect to the binary orbital plane. Interestingly, very recent observations showed that polar CBDs exist in the nature.We check under which conditions the polar alignment of a CBD is expected around an eccentric binary. This is done by constructing dynamical maps of inclined configurations using several chaos indicators. Then, through Smoothed Particle Hydrodynamics (SPH) simulations, we show how the initial conditions for polar alignment can be reached, and also test the recent theoretical predictions based on linear theory. Finally, by means of long-term N-body integrations, we assess the stability of inclined and polar configurations for massless and massive planets.We establish a robust connection between the binary parameters and the resulting CBD polar alignment. Hence, provided that planets form in these discs, we study their stability and long-term evolution for different orbital configurations. In particular, we thoroughly characterise the orbits of single polar circumbinary P-type planets around eccentric binaries.