A First Look at the JWST Phase Curve of WASP-121b with NIRISS/SOSS

Jared Splinter ( Université McGill )

Ultra-hot jupiters have dayside temperatures hot enough to dissociate molecules and vaporize rock/metal-bearing species, but nightsides cool enough for refractory condensates to form clouds. We present the NIRISS phase curve of the ultra-hot jupiter WASP-121b utilizing the SOSS mode (0.6–2.85 µm), obtained as part of Guaranteed Time Observations in Fall 2023; the wavelength coverage is perfectly complementary to the published NIRSpec phase curve. The NIRISS data allow us to constrain molecular abundances of H2O and refractory species, explore the nightside emission of the planet, and analyze the opacity of the H- continuum and make inferences on carbon-bearing species. Combining the NIRSpec/G395H GO phase curve offers the most detailed global view of an exoplanet yet. We perform the most precise exoplanetary energy budget to date and constrain atmospheric temperature structure and heat transport with unprecedented precision.