IRTF Data Archive Program Information

# # Program information file # PROGRAM_ID 2021A052 PROGRAM_TITLE ''Cause You're Hot then You're Cold': Understanding the Variability of Jupiter's Polar Temperatures PROGRAM_INV1 Henrik Melin PROGRAM_INV2 Nahid Chowdhury PROGRAM_INV3 Tom Stallard PROGRAM_INV4 Rosie Johnson PROGRAM_INV5 PROGRAM_SCICAT solar system PROGRAM_ABSTRACT_BEG The upper atmospheres of all the giant planets are hotter than our models predict - this is known as the energy crisis, and the re-distribution of auroral energy is a potential solution. Recent observations of Jupiter's aurora using NASA IRTF iSHELL shows that this region is subject to dramatic and severe changes in the spatial distribution of temperature over time-scales of several weeks. However, we currently do not have the data required to examine the crucial intermediate stages in this re-distribution of energy. To investigate how auroral energy moves within and away from the polar region, we propose to observe the southern auroral region of Jupiter using iSHELL over several days to capture the short and medium-term variability in the temperature. These observations will be coordinated with the Juno spacecraft's close passes of the planet and in particular observations by the near-infrared JIRAM instrument on-board. These will provide high spatial-resolution mappings of temperature and the night-side auroral oval, both which are impossible to achieve from the ground. The iSHELL observations will also provide significant support for the Juno mission by characterising the physical properties of the upper atmosphere before, during and after each spacecraft pass. Using the iSHELL Lp4 setting at Jupiter captures the discrete H3+ emission spectra from which we can retrieve the temperature of the upper atmosphere and ion densities. By scanning the spectral slit sequentially across the polar region, we can therefore generate a complete temperature map every 25 minutes, sufficient to capture any short-term variability. In addition, by observing Jupiter a day before and after the spacecraft pass, we will capture the medium-term variability for the very first time. PROGRAM_ABSTRACT_END