Astronomy and Astrophysics, volume 631A, 28-28 (2019/11-1)
Nearly polar orbit of the sub-Neptune HD 3167 c. Constraints on the dynamical history of a multi-planet system.
DALAL S., HEBRARD G., LECAVELIER DES ETANGS A., PETIT A.C., BOURRIER V., LASKAR J., KONIG P.-C. and CORREIA A.C.M.
Abstract (from CDS):
Aims. We present the obliquity measurement, that is, the angle between the normal angle of the orbital plane and the stellar spin axis, of the sub-Neptune planet HD 3167 c, which transits a bright nearby K0 star. We study the orbital architecture of this multi-planet system to understand its dynamical history. We also place constraints on the obliquity of planet d based on the geometry of the planetary system and the dynamical study of the system.
Methods. New observations obtained with HARPS-N at the Telescopio Nazionale Galileo (TNG) were employed for our analysis. The sky-projected obliquity was measured using three different methods: the Rossiter-McLaughlin anomaly, Doppler tomography, and reloaded Rossiter-McLaughlin techniques. We performed the stability analysis of the system and investigated the dynamical interactions between the planets and the star.
Results. HD 3167 c is found to be nearly polar with sky-projected obliquity, λ=-97°±23°. This misalignment of the orbit of planet c with the spin axis of the host star is detected with 97% confidence. The analysis of the dynamics of this system yields coplanar orbits of planets c and d. It also shows that it is unlikely that the currently observed system can generate this high obliquity for planets c and d by itself. However, the polar orbits of planets c and d could be explained by the presence of an outer companion in the system. Follow-up observations of the system are required to confirm such a long-period companion.
© S. Dalal et al. 2019
techniques: radial velocities - planets and satellites: fundamental parameters - planet-star interactions - planets and satellites: individual: HD 3167
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