# # Program information file # PROGRAM_ID 2022A089 PROGRAM_TITLE Transit Spectroscopy of a Nearby Young Exo-Neptune PROGRAM_INV1 Eric Gaidos PROGRAM_INV2 Rena Lee PROGRAM_INV3 PROGRAM_INV4 PROGRAM_INV5 PROGRAM_SCICAT extra-solar planets PROGRAM_ABSTRACT_BEG Atmospheric escape appears to be an important process that has imprinted itself in the statistical distribution of transiting exoplanets discovered by the Kepler mission. We propose iSHELL spectroscopy in the 1.083-micron line of triplet He I during the transit of a nearby young Neptune-size planet to search for absorption associated with an extended or escaping H/He-dominated atmosphere. We will detect or limit the amount of absorption and use this in a photochemical model of a planetary wind to limit the rate of ongoing atmospheric escape. PROGRAM_ABSTRACT_END