Auroral signature of comet Shoemaker-Levy 9 in the jovian magnetosphere

The electrodynamic interaction of the dust and gas comae of comet Shoemaker-Levy 9 with the jovian magnetosphere was unique and different from the atmospheric effects. Early theoretical predictions of auroral-type processes on the comet magnetic field line and advanced modeling of the time-varying morphology of these lines allowed dedicated observations with the Hubble Space Telescope Wide Field Planetary Camera 2 and resulted in the detection of a bright auroral spot. In that respect, this observation of the surface signature of an externally triggered auroral process can be considered as a "magnetospheric active experiment" on Jupiter.

HST far-ultraviolet imaging of Jupiter during the impacts of comet Shoemaker-Levy 9

Hubble Space Telescope far-ultraviolet images of Jupiter during the Shoemaker-Levy 9 impacts show the impact regions darkening over the 2 to 3 hours after the impact, becoming darker and more extended than at longer wavelengths, which indicates that ultraviolet-absorbing gases or aerosols are more extended, more absorbing, and at higher altitudes than the absorbers of visible light. Transient auroral emissions were observed near the magnetic conjugate point of the K impact site just after that impact. The global auroral activity was fainter than average during the impacts, and a variable auroral emission feature was observed inside the southern auroral oval preceding the impacts of fragments Q1 and Q2.

A Remarkable Auroral Event on Jupiter Observed in the Ultraviolet with the Hubble Space Telescope

Two sets of ultraviolet images of the Jovian north aurora were obtained with the Faint Object Camera on board the Hubble Space Telescope. The first series shows an intense discrete arc in near corotation with the planet. The maximum apparent molecular hydrogen emission rate corresponds to an electron precipitation of approximately 1 watt per square meter, which is about 30,000 times larger than the solar heating by extreme ultraviolet radiation. Such a particle heating rate of the auroral upper atmosphere of Jupiter should cause a large transient temperature increase and generate strong thermospheric winds. Twenty hours after initial observation, the discrete arc had decreased in brightness by more than one order of magnitude. The time scale and magnitude of the change in the ultraviolet aurora leads us to suggest that the discrete Jovian auroral precipitation is related to large-scale variations in the current system, as is the case for Earth's discrete aurorae.

Images of Excited H3+ at the Foot of the lo Flux Tube in Jupiter's Atmosphere

The electrodynamic interaction between lo and the Jovian magnetosphere drives currents to and from the planet's ionosphere, where H(3)(+) emission is excited. Direct images of this phenomenon were obtained with the ProtoCAM infrared camera at the National Aeronautics and Space Administration's 3-m Infrared Telescope Facility. The emissions are localized to the instantaneous foot of the lo flux tube, approximately 8 degrees equatorward of the more intense auroral H(3)(+) emission associated with higher magnetic latitudes. The foot of the lo flux tube leads that of (undisturbed) model magnetic field lines passing through lo by 15 degrees to 20 degrees in longitude and is less visible in the northern hemisphere at longitudes where the surface magnetic field strength is greatest. These data favor the unipolar inductor model of the lo interaction and provide insight into the source location and generation of Jovian decameter radio emission.