IRTF Data Archive Program Information

# # Program information file # PROGRAM_ID 2023B031 PROGRAM_TITLE Fast and Furious: Uranus's [ion] drifts in the southern ionosphere PROGRAM_INV1 Emma Thomas PROGRAM_INV2 Luke Moore PROGRAM_INV3 Tom Stallard PROGRAM_INV4 Henrik Melin PROGRAM_INV5 James O'Donoghue PROGRAM_SCICAT major planets / satellites PROGRAM_ABSTRACT_BEG Uranus' offset, tilted magnetic dipole, combined with the planet's extreme obliquity results in a unique, complex, and poorly understood auroral system. This lack of understanding has been compounded by a history of limited and ambiguous auroral observations. Infrared [IR] observations at Uranus have a 33-year history of observing significant emission enhancements, believed to be the planet's aurorae. These investigations have been unable to confirm this conclusion as they can be explained by non-auroral processes. Here, we propose to complement previous JWST IR images by using IRTF/iSHELL to measure upper-atmospheric ion flows/velocities. JWST data has, to date, produced the highest spatial resolution surveys of Uranus's ionospheric emissions but lacks the spectral resolution to measure ion Doppler shifts. By producing 2D ion velocity maps, iSHELL will enhance the scientific return from these JWST images: identifying signatures of ionosphere-magnetosphere coupling -- i.e., auroral region -- where ions depart from neutral atmospheric co-rotation. Combining these datasets will produce the first complete map of Uranus's southern aurora in over 30 years. The results of which will greatly benefit theory of exoplanetary worlds, providing the first theories of their magnetosphere-ionosphere systems. To achieve these surveys iSHELL will use the LP3 setting, which covers a majority of IR auroral emission lines [specifically from the H3+ ion]. A slit of 15' in length and 0.375' in width is used to collect continuous object and sky calibration frames by nodding between positions. The slit will transition between 3 set latitudes [40degreesS, 50degreesS and 60degreesS] to cover/scan most of the southern aurora with each slit exposure expected to take 35 minutes. Two half nights are requested for these observations as a single half night is expected to record 265degrees of longitude, though these half nights must be sequential so observations can record a whole rotation of Uranus. PROGRAM_ABSTRACT_END