WASP-128b: a transiting brown dwarf in the dynamical-tide regime

Hodzic, Vedad; Triaud, Amaury H. M. J.; Anderson, David R.; Bouchy, Francois; Cameron, Andrew Collier; Delrez, Laetitia; Gillon, Michael; Hellier, Coel; Jehin, Emmanuel; Lendl, Monika; Maxted, Pierre F. L.; Pepe, Francesco; Pollacco, Don; Queloz, Didier; Segransan, Damien; Smalley, Barry; Udry, Stephane; West, Richard

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 ± 0.04M?, R? = 1.16 ± 0.02R?, 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

Hodzic, V., Triaud, A. H. M. J., Anderson, D. R., Bouchy, F., Cameron, A. C., Delrez, L., …West, R. (2018). WASP-128b: a transiting brown dwarf in the dynamical-tide regime. Monthly Notices of the Royal Astronomical Society, 481(4), 5091-5097. https://doi.org/10.1093/mnras/sty2512

• Journal Article Type: Article
• Acceptance Date: Aug 27, 2018
• Online Publication Date: Sep 14, 2018
• Publication Date: 2018-12
• Publicly Available Date: May 26, 2023
• Journal: Monthly Notices of the Royal Astronomical Society
• Print ISSN: 0035-8711
• Publisher: Oxford University Press
• Peer Reviewed: Peer Reviewed
• Volume: 481
• Issue: 4
• Pages: 5091-5097
• DOI: https://doi.org/10.1093/mnras/sty2512
• Keywords: methods, data analysis, brown dwarfs, binaries, eclipsing, planets and satellites, dynamical evolution and stability
• Publisher URL: http://dx.doi.org/10.1093/mnras/sty2512