TOI-858 B b: A hot Jupiter on a polar orbit in a loose binary
Bouchy, F.; Stassun, K.; Winn, J. N.; Collins, K. A.; Seager, S.; Udry, S.; Bourrier, V.; Jones, M. I.; Wang, S.; Bouma, L. G.; Latham, D. W.; Hagelberg, J.; Hellier, C.; Venturini, J.; Briceño, C.; Mann, A. W.; Nielsen, L. D.; Grieves, N.; Ottoni, G.; Pearce, L.; Marmier, M.; Ziegler, C.; Law, N.; Stockdale, C.; Eastman, J. D.; Evans, P.; Guerrero, N. M.; Attia, M.; Rudat, A.; Falk, B.; Davis, A. B.; Radford, D. J.; Restori, N.; Dos Santos, L.
Switzerland, Germany, United States, Chile, United Kingdom, Australia, Canada
Abstract
We report the discovery of a hot Jupiter on a 3.28-day orbit around a 1.08 M⊙ G0 star that is the secondary component in a loose binary system. Based on follow-up radial velocity observations of TOI-858 B with CORALIE on the Swiss 1.2 m telescope and CHIRON on the 1.5 m telescope at the Cerro Tololo Inter-American Observatory (CTIO), we measured the planet mass to be 1.10‑0.07+0.08 MJ. Two transits were further observed with CORALIE to determine the alignment of TOI-858 B b with respect to its host star. Analysis of the Rossiter-McLaughlin signal from the planet shows that the sky-projected obliquity is λ = 99.3‑3.7+3.8°. Numerical simulations show that the neighbour star TOI-858 A is too distant to have trapped the planet in a Kozai–Lidov resonance, suggesting a different dynamical evolution or a primordial origin to explain this misalignment. The 1.15 M⊙ primary F9 star of the system (TYC 8501-01597-1, at ρ ~11″) was also observed with CORALIE in order to provide upper limits for the presence of aplanetary companion orbiting that star. ★Tables A.1–A.3 are available at the CDS via anonymous ftp to cdsarc.cds.unistra.fr (130.79.128.5) or via https://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/679/A70