Jupiter in 2010- Report no.12

NEBn: Second merger of anticyclonic white ovals

(Yuichi Iga & John Rogers, 2010 Oct.12)

A second merger of anticyclonic white ovals in the NEBn occurred in late September. This merger at L2 ~ 330 was also covered at very high spatial and temporal resolution, and Yuichi Iga made the attached compilation of images.  The p. oval was small, and only a month old, so this was not a merger of equals. Indeed it proceeded more like the mergers of unequal AWOs recorded in the NEBn in previous years. The ovals converged without hesitation, contacted on Sep.25, and immediately began a complex spiral interaction that was imaged at hi-res.  However the smaller oval retained its identity and motion, and by Sep.28 it had proceeded past the larger oval, and was a streak squeezing against an adjacent barge.  It then disappeared before or on Oct.2. (Meanwhile on Oct.2, a new white spot erupted Sp. this barge, very bright at all wavelengths including methane and UV; this was another new rift, probably unrelated to the AWOs.)  The larger oval became dull during the interaction and has remained dull up to Oct.6.  IR and UV images also showed the interaction very clearly, generally consistent with the visible-light images, although Parker's images on Oct.2 showed the remaining oval was still complex in UV although small and dull in other wavelengths. In methane images, both ovals were bright before the merger (rather unusual for AWOs in NEBn). During the spiralling on Sep.27, the northern component (the larger oval) was very methane-bright, the disrupted smaller oval less so. Neither was methane-bright by Oct.2. (In the methane images, note the very dark broad belt corresponding the the visible narrow blue-grey NTropB, which abuts the AWOs; it is slightly south of the true NTB(S) seen at other wavelengths.)