OUTBURST OF JUPITER SYNCHROTRON-RADIATION AFTER THE IMPACT OF COMET SHOEMAKER-LEVY-9

Jupiter's nonthermal microwave emission, as measured by a global netwo rk of 11 radio telescopes, increased dramatically during the Shoemaker -Levy 9 impacts. The increase was wavelength-dependent, varying from s imilar to 10 percent at 70 to 90 centimeters to similar to 45 percent at 6 and 36 centimeters. The radio spectrum hardened (flattened toward shorter wavelengths) considerably during the week of impacts and cont inued to harden afterward. After the week of cometary impacts, the flu x density began to subside at all wavelengths and was still declining 3 months later. Very Large Array and Australia Telescope images of the brightness distribution showed the enhancement to be localized in lon gitude and concentrated near the magnetic equator. The evidence theref ore suggests that the increase in flux density was caused by a change in the resident particle population, for example, through an energizat ion or spatial redistribution of the emitting particles.