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A. Sanchez-Lavega (UPV), G. S. Orton (JPL), R. Morales (UPV), J. Lecacheux (Obs. Meudon), F. Colas (I. Mecanique), B. Fisher (JPL), P. Fukumura-Sawada, W. Golisch, D. Griep, C. Kaminski (I. A. Hawaii), K. Baines (JPL), K. Rages (SPRI), R. West (JPL)
Two giant ovals in Jupiter's southern atmosphere, vortices of counterclockwise-rotating winds, merged in a 3-week period, starting in March 2000. One of the ovals called FA was more than 60 years old; the other called BE was the product of two 60-year ovals (BC and DE) that merged in 1998 (Sanchez-Lavega et al., Icarus, Vol. 142, 116. 1999). Here we report the coordinated observations of the BE - FA merger obtained with different facilities: The 1 - m Pic-du-Midi telescope (visual wavelength range), the 3.5 m NASA - IRTF telescope (red and near infrared range) and the Hubble Space Telescope (visual range). The merger took place when the ovals were southeast of the Great Red Spot and after the disappearance of a smaller, clockwise-rotating oval midway between them. The interaction began when the high-altitude oval clouds showed counterclockwise rotation about each other, followed by coalescence and shrinking. The interaction in deeper clouds did not include mutual rotation, but there was evidence of complex cloud structure during the merger. After 60 years, these three vortices consolidate into a single vortex that could now either (1) merge with the large, axisymmetric high-albedo band from which the ovals were originally formed or (2) continue as a stable and long-lived vortex in Jupiter. If the new oval (BA) is long-lived, then it is tempting to speculate that the more than 300-year old Great Red Spot could have had a similar genesis.
The Spanish team was supported by Gobierno Vasco PI 034/97. The French team was supported by the "Programme National de Planetologie." The US team was supported by NASA through grants to the Institute for Astronomy (U. Hawaii) and JPL. Some of the observations were made by the NASA-ESA Hubble Space Telescope, with support provided through grant GO-8148 from the Space Telescope Science Institute which is operated by the Association of Universities for Research in Astronmy under NASA contract NAS5-26555. RM acknowledges a fellowship from Universidad Pais Vasco.