Jupiter After the Impact

Three months after Comet Shoemaker-Levy 9 slammed into Jupiter, the planet's magnetic field still simmers.

Energized particles trapped in the field continue to emit above-normal amounts of microwave radiation, so that even now Jupiter's radio brightness is around 10 percent above pre-impact levels.

The emissions are synchrotron radiation from high-energy particles--primarily electrons--caught in Jupiter's radiation belts, which are similar to Earth's Van Allen belts, says Imke de Pater, professor of astronomy.

According to de Pater, the most likely explanation for the increased microwave flux is that the impact generated strong waves in the planet's magnetosphere, called magneto-sonic waves, that accelerated particles in the radiation belt to even higher energies.

As a result they emit more radio waves and will continue to do so until they have lost all their energy or are absorbed by Jupiter, a moon, or dust around the planet.

De Pater reported the most recent data Oct. 31 at the meeting of the American Astronomical Society's Division of Planetary Sciences. She leads a large team of astronomers observing the planet at 10 radio telescopes around the world.

De Pater's Berkeley colleagues include astronomy professor Carl Heiles and graduate student Michael Wong.

--Robert Sanders


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