Keck/NIRSPEC studies of helium in the atmospheres of two inflated hot gas giants orbiting K dwarfs: WASP-52b and WASP-177b

The helium triplet at 1083 nm has recently emerged as a powerful new observational probe of exoplanet atmospheric loss. We are using this new technique to conduct a survey of atmospheric escape in inflated hot gas giants using the NIRSPEC instrument on the Keck II telescope. Here we present the detection of helium in the atmosphere of WASP-52b, extending over 66 ± 5 scale heights, and find tentative evidence of helium in the atmosphere of WASP-177b at around 23 scale heights. By modeling the helium absorption profile, we find WASP-52b is losing its mass at a rate of ~1.6 × 10¹¹ g/s. Finally, we place our results into the context of the ~30 exoplanets that have been the focus of helium studies to date.