IRTF Data Archive Program Information

# # Program information file # PROGRAM_ID 2021B079 PROGRAM_TITLE Revealing the complete infrared aurorae of Uranus PROGRAM_INV1 Emma Thomas PROGRAM_INV2 Henrik Melin PROGRAM_INV3 Tom Stallard PROGRAM_INV4 Luke Moore PROGRAM_INV5 James O'Donoghue PROGRAM_SCICAT solar system PROGRAM_ABSTRACT_BEG Uranus' aurorae are the least understood in our Solar System but yet the most unique due to their asymmetric nature and dissimilarity to aurorae at Earth or Jupiter and Saturn. It has been 45 years since the Uranian aurorae were first observed in the ultraviolet spectrum, and yet we have never obtained a complete infrared aurorae map to this date. By obtaining this mapping of Uranus' upper atmosphere and aurorae in 2021 [now entering southern summer solstice], we can directly compare to our partial mapping at equinox [2006], gaining insight into how Uranus' magnetosphere has evolved with seasonal change. During late 2021 we gain an opportunity to observe the southern aurora both directly facing towards the sun and almost perpendicular, a prime occasion to investigate how the aurorae vary between these phases. Further comparisons with the 1986 morphology indicate how our observations fit with Uranus' longitude system [ULS], enabling us to re-establish the long lost ULS coordinate system. Ultimately our results will guide our hypotheses of exoplanet aurorae and their behaviour, due to an ever-increasing number of ice giant-like exoplanets. Hence, we propose two and a half nights of observations with IRTF iSHELL close to early November to complete a full auroral map, closest to Uranus opposition, by aligning a 0.75x15' slit with the rotational axis of Uranus. Each observational night we will observe 9 hours of planetary rotation, or approximately 190 degree longitude per run, [90 degree for the half night run], with a total overlap of 100 degree across all nights, we will achieve a full 360 degree map of infrared emissions at Uranus. By analysing the H3+ intensities observed, we can relate these as well as temperatures and column densities to latitude and longitudinal positions and hence produce the first ever global map of infrared auroral emissions. PROGRAM_ABSTRACT_END