HST-COS Transit Spectroscopy of KELT-20b: First Detection of Excess Far-ultraviolet Absorption From an Ultra-hot Jupiter

Patrick R. Behr, Kevin France, Luca Fossati +4

KELT-20 b is an ultra-hot Jupiter with an equilibrium temperature of $2260$ K orbiting a bright (V =7.6), fast-rotating ($v\sin i$=117 km s${}^{-1}$) A2 V star. The atmosphere of KE…