Observational constraints on the atmospheric dynamics of the inspiraling ultra-hot Jupiter WASP-12 b

Atmospheric escape of highly irradiated planets is a relevant phenomenon that shapes entire populations of exoplanets and poses direct consequences for the habitability of terrestrial planets. WASP-12 b is an ultra-hot Jupiter of particular interest for studies of atmospheric escape since it is on an observably inspiraling orbit which may enhance mass outflow from the planet as it heats up in closer proximity to its host star. Previous works have identified tentative evidence both for and against the detection of active mass loss from the atmosphere of this planet. To address this controversy, we analyze two new transits of WASP-12 b with the optical high-resolution PEPSI spectrograph on the Large Binocular Telescope. From these data, we place constraints on atmospheric escape from upper limits on planetary Balmer line absorption. We also conduct a spectral survey of atomic species present in WASP-12 b’s atmosphere to trace atmospheric circulation and conduct comparative planetology by evaluating the composition of WASP-12 b’s atmosphere in the broader context of the overall ultra-hot Jupiter population observed thus far.