Physical Sciences and Mathematics Commons^™

An Hst/Stis Optical Transmission Spectrum Of Warm Neptune Gj 436b, Joshua D. Lothringer, Björn Benneke, Ian J. M. Crossfield, Gregory W. Henry, Caroline Morley, Diana Dragomir, Travis Barman, Heather Knutson, Eliza Kempton, Jonathan J. Fortney, Peter Mccullough, Andrew W. Howard

Information Systems and Engineering Management Research Publications

GJ 436b is a prime target for understanding warm Neptune exoplanet atmospheres and a target for multiple James Webb Space Telescope (JWST) Guaranteed Time Observation programs. Here, we report the first space-based optical transmission spectrum of the planet using two Hubble Space Telescope (HST) Space Telescope Imaging Spectrograph (STIS) transit observations from 0.53 to 1.03 μm. We find no evidence for alkali absorption features, nor evidence of a scattering slope longward of 0.53 μm. The spectrum is indicative of moderate to high metallicity (∼100–1000× solar), while moderate-metallicity scenarios (∼100× solar) require aerosol opacity. The optical spectrum also rules out some …