WASP-103 b : a new planet at the edge of tidal disruption

Abstract

We report the discovery of WASP-103 b, a new ultra-short-period planet (P = 22.2 h) transiting a 12.1 V-magnitude F8-type main-sequence star (1.22 ± 0.04 M⊙, 1.44-0.03+0.05 R⊙, Teff = 6110 ± 160 K). WASP-103 b is significantly more massive (1.49 ± 0.09 MJup) and larger (1.53-0.07+0.05 RJup) than Jupiter. Its large size and extreme irradiation (~ 9 × 109 erg s-1 cm-2) make it an exquisite target for a thorough atmospheric characterization with existing facilities. Furthermore, its orbital distance is less than 20% larger than its Roche radius, meaning that it might be significantly distorted by tides and might experience mass loss through Roche-lobe overflow. It thus represents a new key object for understanding the last stage of the tidal evolution of hot Jupiters.