WASP-128b : a transiting brown dwarf in the dynamical-tide regime
Abstract
Massive companions in close orbits around G dwarfs are thought to undergo rapid orbital decay due to runaway tidal dissipation. We report here the discovery of WASP-128b, a brown dwarf discovered by the WASP survey transiting a G0V host on a 2.2 d orbit, where the measured stellar rotation rate places the companion in a regime where tidal interaction is dominated by dynamical tides. Under the assumption of dynamical equilibrium, we derive a value of the stellar tidal quality factor logQ′⋆=6.96 ± 0.19. A combined analysis of ground-based photometry and high-resolution spectroscopy reveals a mass and radius of the host, M⋆ = 1.16 ± 0.04 M⊙, R⋆ = 1.16 ± 0.02 R⊙, and for the companion, Mb = 37.5 ± 0.8Mj, Rb = 0.94 ± 0.02Rj, placing WASP-128b in the driest parts of the brown dwarf desert, and suggesting a mild inflation for its age. We estimate a remaining lifetime for WASP-128b similar to that of some ultra-short period massive hot Jupiters, and note it may be a propitious candidate for measuring orbital decay and testing tidal theories.
Citation
Hodžić , V , Triaud , A H M J , Anderson , D R , Bouchy , F , Cameron , A C , Delrez , L , Gillon , M , Hellier , C , Jehin , E , Lendl , M , Maxted , P F L , Pepe , F , Pollacco , D , Queloz , D , Ségransan , D , Smalley , B , Udry , S & West , R 2018 , ' WASP-128b : a transiting brown dwarf in the dynamical-tide regime ' , Monthly Notices of the Royal Astronomical Society , vol. 481 , no. 4 , pp. 5091–5097 . https://doi.org/10.1093/mnras/sty2512
Publication
Monthly Notices of the Royal Astronomical Society
Status
Peer reviewed
ISSN
0035-8711Type
Journal article
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