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WASP-131 b with ESPRESSO – I. A bloated sub-Saturn on a polar orbit around a differentially rotating solar-type star

Doyle, L; Cegla, HM; Anderson, DR; Lendl, M; Bourrier, V; Bryant, E; Vines, J; ... Wheatley, P; + view all (2023) WASP-131 b with ESPRESSO – I. A bloated sub-Saturn on a polar orbit around a differentially rotating solar-type star. Monthly Notices of the Royal Astronomical Society , 522 (3) pp. 4499-4514. 10.1093/mnras/stad1240. Green open access

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Abstract

In this paper, we present observations of two high-resolution transit data sets obtained with ESPRESSO of the bloated sub-Saturn planet WASP-131 b. We have simultaneous photometric observations with NGTS and EulerCam. In addition, we utilized photometric light curves from TESS, WASP, EulerCam, and TRAPPIST of multiple transits to fit for the planetary parameters and update the ephemeris. We spatially resolve the stellar surface of WASP-131 utilizing the Reloaded Rossiter McLaughlin technique to search for centre-to-limb convective variations, stellar differential rotation, and to determine the star-planet obliquity for the first time. We find WASP-131 is misaligned on a nearly retrograde orbit with a projected obliquity of λ = 162.4+1.3â-¦−1.2. In addition, we determined a stellar differential rotation shear of α = 0.61 ± 0.06 and disentangled the stellar inclination (i∗ = 40.9+13.3â-¦−8.5 from the projected rotational velocity, resulting in an equatorial velocity of veq = 7.7+1.5−1.3. In turn, we determined the true 3D obliquity of ψ = 123.7+12.8â-¦−8.0, meaning the planet is on a perpendicular/polar orbit. Therefore, we explored possible mechanisms for the planetary system's formation and evolution. Finally, we searched for centre-to-limb convective variations where there was a null detection, indicating that centre-to-limb convective variations are not prominent in this star or are hidden within red noise.

Type: Article
Title: WASP-131 b with ESPRESSO – I. A bloated sub-Saturn on a polar orbit around a differentially rotating solar-type star
Open access status: An open access version is available from UCL Discovery
DOI: 10.1093/mnras/stad1240
Publisher version: http://dx.doi.org/10.1093/mnras/stad1240
Language: English
Additional information: © 2023 The Author(s). Published by Oxford University Press on behalf of Royal Astronomical Society. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited.
Keywords: convection, techniques: radial velocities, planets and satellites: fundamental parameters, stars: individual: WASP-131, stars: rotation
UCL classification: UCL
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Space and Climate Physics
URI: https://discovery.ucl.ac.uk/id/eprint/10191949
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