Delrez, L, Santerne, A, Almenara, J-M, Anderson, DR, Collier-Cameron, A, Diaz, RF, Gillon, M, Hellier, C, Jehin, E, Lendl, M, Maxted, PFL, Neveu-VanMalle, M, Pepe, F, Pollacco, D, Queloz, D, Segransan, D, Smalley, B, Smith, AMS, Triaud, AHMJ, Udry, S, Van Grootel, V and West, RG (2016) WASP-121 b: a hot Jupiter close to tidal disruption transiting an active F star. Monthly Notices of the Royal Astronomical Society, 458 (4). 4025 - 4043. ISSN 1365-2966

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We present the discovery by the WASP-South survey of WASP-121 b, a new remarkable short-period transiting hot Jupiter. The planet has a mass of 1.183+0.064−0.062MJup, a radius of 1.865 ± 0.044 RJup, and transits every 1.2749255+0.0000020−0.0000025 days an active F6-type main-sequence star (V = 10.4, 1.353+0.080−0.079 M⊙, 1.458 ± 0.030 R⊙, Teff = 6460 ± 140 K). A notable property of WASP-121 b is that its orbital semimajor axis is only ∼1.15 times larger than its Roche limit, which suggests that the planet is close to tidal disruption. Furthermore, its large size and extreme irradiation (∼7.1 109 erg s−1 cm−2) make it an excellent target for atmospheric studies via secondary eclipse observations. Using the TRAnsiting Planets and PlanetesImals Small Telescope, we indeed detect its emission in the z′-band at better than ∼4σ, the measured occultation depth being 603 ± 130 ppm. Finally, from a measurement of the Rossiter–McLaughlin effect with the CORALIE spectrograph, we infer a sky-projected spin-orbit angle of 257∘.8+5∘.3−5∘.5⁠. This result may suggest a significant misalignment between the spin axis of the host star and the orbital plane of the planet. If confirmed, this high misalignment would favour a migration of the planet involving strong dynamical events with a third body.

Item Type: Article
Additional Information: This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2016 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.
Uncontrolled Keywords: techniques, photometric, radial velocities, spectroscopic, stars, individual, WASP-121, planetary systems
Subjects: Q Science > QB Astronomy
Divisions: Faculty of Natural Sciences > School of Physical and Geographical Sciences
Related URLs:
Depositing User: Symplectic
Date Deposited: 03 Nov 2016 10:46
Last Modified: 11 Apr 2019 08:53

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