TRAPPIST-1 Atmospheric Reconnaissance with JWST: First Look at the Habitable-Zone Exoplanet TRAPPIST-1 f with NIRISS

One of the most intriguing unanswered questions in the field of exoplanets is whether Earth-like planets outside our solar system have atmospheres suitable for the emergence of life. Located in the solar neighborhood with seven Earth-sized, rocky, transiting planets, three which being in the habitable zone, TRAPPIST-1 may be our best shot at detecting and potentially characterizing atmospheres on small temperate exoplanets. So far, the search for atmospheres on TRAPPIST-1 planets has been an exciting adventure full of challenges. Transit observations with HST rejected cloud-free, hydrogen-rich atmospheres on all seven planets. Secondary eclipse observations of TRAPPIST-1 b with JWST/MIRI initially ruled out any thick atmospheres based on the inferred lack of heat redistribution, but additional observations at 12.8 um suggest that a thick, hazy, CO2-rich atmosphere is also consistent with the data. For TRAPPIST-1 c, secondary eclipse observations with MIRI rejected any thick CO2 atmospheres, but thinner atmospheres remain possible. In transmission, JWST/NIRISS revealed strong evidence for stellar contamination from unocculted spots and faculae. Is there still hope to find atmospheres on the outer, cooler planets? In this talk, we will present, for the first time, the first JWST transmission spectra of the habitable-zone planet TRAPPIST-1 f obtained with NIRISS, and discuss lessons learned from JWST observations of this unique system and possible strategies for future observations.