The Spectacular Swan Song of Shoemaker-Levy 9

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Session 72 -- Invited Talks: Impacts and Vulcanism
Invited presentation, Tuesday, 10, 1995, 3:40pm

[72.01] The Spectacular Swan Song of Shoemaker-Levy 9

H.B.Hammel (MIT)

In July 1994, the fragments of Comet Shoemaker-Levy 9 plunged into Jupiter over a period of several days. I will discuss the changes created by this cataclysmic collision on the visible regions of Jupiter's atmosphere, based primarily on inaging obtained with the Hubble Space Telescope (HST) before, during, and after the impacts, and also on other selected observations. Many effects on Jupiter's atmosphere were detectable. For four separate events (A, E, G, and W), fireball plumes were detected rising above the limb of Jupiter; some of these plumes reached heights of 4000 kilometers. The plumes were visible in Jupiter's shadow, probably in thermal emission; above the shadow, they reflected sunlight. In three cases (A, G, and W), the incoming bolide, may have been detected, although rising plume material or bolide light scattered off cometary dust may also have contributed to the observed emission. Plume heights and estimates of ejection velocities will be discussed. Several fresh impact sites were observed, and transient expanding rings were detected around several sites (A, E, G, R, and Q1), caused by horizontal propagation of an atmospheric wave; measurements of these waves yield a wave speed of 490 +/- 70 m/sec. Thin ejecta blankets sometimes extended up to 16,000 km from the impact sites. The distribution of material was asymmetric; the patterns were consistent with ejection back along the sloping path of the incoming projectile. Positions were determined for all detected impact sites (F, P2, T, U, and V were not seen). Several features evolved throughout the week of impacts due to the jovian winds. Hubble also imaged impact sites over a period of several weeks to watch the long-term effects of atmospheric circulation on impact-created debris. I will present an overview of these observations, and discuss the probable future of the new atmospheric disturbances on Jupiter.

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