EFFECTS ON JUPITER SYNCHROTRON RADIO-EMISSION AT LAMBDA-90 CM DUE TO THE INFALL OF COMET-D SHOEMAKER-LEVY-9

During the impacts of the fragmented Comet D/Shoemaker-Levy 9, Jupiter 's synchrotron radio emission at lambda 90 cm was monitored using the Very Large Array (VLA) and Westerbork Synthesis Radio Telescope, The d ramatic infall of the comet onto Jupiter temporarily induced significa nt changes in the planet's radiation belts. The total flux density of Jupiter increased steadily and decreased later, reaching below pre-imp act levels. The ratio of the emission peaks changed dramatically, part icularly around July 19-20, indicating pronounced E/W asymmetries indu ced after the impacts of fragments K and L. Comparing with similar dat a at lambda 20 cm, the changes induced in the E/W ratios are essential ly equal at both lambda 90 and lambda 20 cm. At lambda 90 cm, however, the VLA images obtained on July 19-20 also revealed, for the first ti me, the temporal evolution of a compact component in the radiation mor phology. This compact feature might be associated with the infall of f ragments K and L on 1994 July 19, The observations suggest that this f eature appeared at a radial distance range of approximate to 6.3-6.7R( J), assuming it was corotating with Jupiter while steadily diminishing in its brightness. (C) 1998 Academic Press.