Planet formation in polar circumbinary discs

N. CUELLO; C. A. GIUPPONE

Bordeaux

Congreso; Semaine de l'Astrophysique Française; 2018

Société Française d?Astronomie & d?Astrophysique (SF2A)

Due to observational biases, circumbinary planet detections are rather rare. In fact, up to now, only a handful of binary systems with planets have been reported (mainly by Kepler). However, planet formation is expected to occur around binary stars as well. Dynamical studies suggest that most of the circumbinary discs should be coplanar, i.e. the rotation vectors of the binary and the disc are aligned. Interestingly, some recent theoretical works show that under certain conditions circumbinary discs can become polar, which means that the rotation vectors are orthogonal. In this work, we explore how these conditions could be reached and we assess how likely is the disc to become polar with respect to the binary. We present 3D smoothed particle hydrodynamics simulations of misaligned discs and follow their resulting alignments. In addition, we study the stability of the polar configurations through N-body simulations. Gathering, both SPH and dynamics analysis, we confirm previous predictions and show a vast kind of configurations that lead to polar and retrograde discs. Hence, the resulting planetary architectures should be polar, as well as retrograde. Despite their low probability of detection, we suggest that S-type "polar planets" might be rather common around binary stars.