Fig. 1. Measured helium excess in HAT-P-32 A+b planetary system.

EWs of the helium 10,833-Å triplet, measured from the observed spectra of HAT-P-32 A + b (top) and computed residual spectra of HAT-P-32 b (bottom), exhibit long-duration (12 hours), significant (14σ) excess near the planet’s transits. Solid circles represent data obtained within two nights of each optical transit, and open circles represent the stellar variability monitoring data obtained from out-of-transit periods. We divided the data into five categories in terms of orbital phase, with boundaries highlighted by gray-shaded regions. Our three-dimensional (3D) hydrodynamic simulation is shown as the gray solid line. The time-series helium EWs are asymmetric with respect to the planet’s optical transit (dark gray), demonstrating the leading tail of the helium atmosphere escaping HAT-P-32 b.