A puffy polar planet. The low density, hot Jupiter TOI-640 b is on a polar orbit

Knudstrup, Emil; Albrecht, Simon H.; Gandolfi, Davide; Marcussen, Marcus L.; Goffo, Elisa; Serrano, Luisa M.; Dai, Fei; Redfield, Seth; Hirano, Teruyuki; Csizmadia, Szilárd; Cochran, William D.; Deeg, Hans J.; Fridlund, Malcolm; Lam, Kristine W. F.; Livingston, John H.; Luque, Rafael; Narita, Norio; Palle, Enric; Persson, Carina M.; Van Eylen, Vincent
Bibliographical reference

Astronomy and Astrophysics

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3
2023
Number of authors
20
IAC number of authors
3
Citations
4
Refereed citations
4
Description
TOI-640 b is a hot, puffy Jupiter with a mass of 0.57 ± 0.02 MJ and radius of 1.72 ± 0.05 RJ, orbiting a slightly evolved F-type star with a separation of 6.33−0.06+0.07 R⋆. Through spectroscopic in-transit observations made with the HARPS spectrograph, we measured the Rossiter-McLaughlin effect, analysing both in-transit radial velocities and the distortion of the stellar spectral lines. From these observations, we find the host star to have a projected obliquity of λ = 184 ± 3°. From the TESS light curve, we measured the stellar rotation period, allowing us to determine the stellar inclination, i⋆ = 23−2+3°, meaning we are viewing the star pole-on. Combining this with the orbital inclination allowed us to calculate the host star obliquity, ψ = 104 ± 2°. TOI-640 b joins a group of planets orbiting over stellar poles within the range 80°-125°. The origin of this orbital configuration is not well understood.
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