干旱区生态环境知识资源中心

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 log Q(star)’ = 6.96 +/- 0.19. A combined analysis of ground-ased photometry and high-resolution spectroscopy reveals a mass and radius of the host, M-star = 1.16 +/- 0.04M(circle dot), R-star = 1.16 +/- 0.02R(circle dot), and for the companion, M-b = 37.5 +/- 0.8 M-J, R-b = 0.94 +/- 0.02 R-J,R- 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.