Author ORCID Identifier
Date of Award
Doctor of Philosophy (PhD)
Physics and Astronomy
Stuart M. Jefferies
Although we have learned much about Jupiter throughout history, many questions still remain, with one in particular that we seek to answer: does a solid core lie at the center of the planet, or is it gaseous and metallic throughout? To uncover this mystery, we turn to seismology, a sole remaining way to directly and unambiguously probe the deepest interior of Jupiter. We have developed a novel set of instrumentation, called PMODE -- the Planetary Multilevel Oscillations & Dynamics Experiment, a triple-channel instrument to probe the Jovian interior through seismic techniques. Here, we focus on the 770 nm potassium Doppler imager. This channel is developed to measure the Doppler shift of reflected sunlight off the Jovian clouds; these shifts contain information on the densities deep within the planet. With PMODE, we have collected 24 nights of observations in August 2020 from the 3.6m AEOS telescope, located on Mount Haleakala, HI.
From these observations, we have produced a sensitive measurement of the high-frequency components of the Jovian zonal winds, alleviating contradiction between the sole previous Doppler measurement and the well studied cloud tracking measurement. We provide evidence that the PMODE Doppler measurement, combined with a separate measurement sensitive to the low-spatial frequency components (such as the previous Doppler measurement), will accurately reproduce the profile from feature tracking models. We refute the previous report of detection of Jovian global modes with amplitudes of 50 cm/s, and instead place a constraint of 4.5 cm/s for amplitudes in the mode of historical interest. This new constraint eliminates rock storms as an excitation mechanism present in the Jovian interior, implying that any existing oscillations will likely have amplitudes below 1 cm/s. Finally, we discuss avenues to detect these smaller amplitudes in the future, and conclude that inclusion of a Doppler velocimeter on a Jovian orbiter may provide the only chance at an unambiguous detection of the global modes of Jupiter.
Gulledge, Deborah, "Expanding the Search for the Pulse of Jupiter." Dissertation, Georgia State University, 2022.
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