The Atmosphere of Titan in Late Northern Summer from JWST and Keck Observations

Abstract

Saturn's moon Titan undergoes a long annual cycle of 29.45 Earth years. Titan's northern winter and spring were investigated in detail by the Cassini-Huygens spacecraft (2004-2017), but the northern summer season remains sparsely studied. Here we present new observations from the James Webb Space Telescope (JWST) and Keck II telescope made in 2022 and 2023 during Titan's late northern summer. Using JWST's mid-infrared instrument, we spectroscopically detected the methyl radical, the primary product of methane break-up and key to the formation of ethane and heavier molecules. Using the near-infrared spectrograph onboard JWST, we detected several non-local thermodynamic equilibrium CO and CO2 emission bands, which allowed us to measure these species over a wide altitude range. Lastly, using the near-infrared camera onboard JWST and Keck II, we imaged northern hemisphere tropospheric clouds evolving in altitude, which provided new insights and constraints on seasonal convection patterns. These observations pave the way for new observations and modelling of Titan's climate and meteorology as it progresses through the northern fall equinox, when its atmosphere is expected to show notable seasonal changes.

41 pages, 12 figures, 1 table

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Cited by in corpus (4)

• Insufficient evidence for DMS and DMDS in the atmosphere of K2-18 b. From a joint analysis of JWST NIRISS, NIRSpec, and MIRI observations
• Photochemical Haze Formation on Titan and Uranus: A Comparative Review
• Collisional Excitation in Space: Recent Advances and Future Challenges in the JWST Era
• Disk-averaged spectrum generation for spherically symmetric planets and moons