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Titan’s winds from a 2022 stellar occultation observed with Keck adaptive optics

Presentation #208.09 in the session Titan I: Atmosphere (Oral Presentation)

Published onOct 23, 2023
Titan’s winds from a 2022 stellar occultation observed with Keck adaptive optics

Titan presents a unique opportunity to study a primitive terrestrial-type atmosphere, yet the seasonal evolution of its zonal wind structure is still poorly constrained. General circulation models (GCMs) predict rapid changes in zonal wind for the few years around equinox in 2025. We are therefore in a critical time to collect observations that further our understanding of Titan’s seasonal evolution and test model predictions. Stellar occultations provide key constraints on wind profiles at altitudes of roughly 250-450 km (the mid stratosphere through lower mesosphere). We observed an occultation of a star by Titan with adaptive optics on the Keck II telescope on September 5, 2022 (angular resolution of 50 mas). The use of adaptive optics allowed Titan to be resolved into multiple elements (~250 km resolution at Titan), and the refracted starlight along the limb to be directly imaged. Characterization of the refracted light from around the limb allows determination of non-spherical distortions and a corresponding meridional stratospheric zonal wind profile. Our observations were near-concurrent with ALMA observations, which measured winds via the Doppler shifts of specific molecular emission lines. The AO and ALMA observations yield a powerful combination of tools to study Titan’s current wind patterns. Here, we present an overview of the research to date on determining the meridional profile of Titan’s stratospheric zonal wind, our data collected from the September 2022 occultation, and our steps toward modeling this data to constrain Titan’s stratospheric zonal wind in the post-Cassini era.

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