Io from Ground-based Eclipse Observations: Implications for the Eruptive History of Loki

Loki is the most powerful volcano on Io, the most volcanically active body in the solar system. We have been observing infrared thermal emission from Io's volcanoes using NASA's Infrared Telescope Facility (IRTF) for nearly two decades. Measurements of Loki's 3.5 micron brightness from Jupiter occultation lightcurves have indicated that it often erupts in a regular and predictable manner and have been used to constrain models of Loki's eruption behavior, indicating the behavior at this wavelength is consistent with a periodically overturning lava lake. Knowledge of Loki's brightness at additional wavelengths would help to further constrain these models. Our observations also include eclipse images of Io's volcanic emission at 2.3, 3.5, and 4.7 microns, which can also be used to constrain the eruption models if Loki's flux can be separated from that of other volcanoes. We will analyze all of the already obtained eclipse observations of Io and measure Io's brightness at the three wavelengths. We will also determine the number of active volcanoes on a given night based on the occultation lightcurve. From this information, we will determine how to extract approximate Loki brightnesses from the integrated Io brightnesses. Finally, we will compare the calculated multi-wavelength Loki brightnesses to the model of Loki as an overturning lava lake.