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A. Sánchez-Lavega, S. Pérez-Hoyos (Universidad Pais Vasco (Spain)), R. G. French (Wellesley College)
Yearly HST imaging from 1997 to 2002 using the Wield Field Planetary Camera 2 with a series of filters ranging from the UV (218 nm) to the near IR (1042 nm), have revealed the motions and episodic cloud morphology changes in the South Polar Region of Saturn, poleward -70 deg. The images do not show either a ``hexagonal" wave nor an anticyclone, counterparts to those seen in the North Pole at + 78 deg. However, a polar jet similar in location, amplitude and width, to that in which the North Polar hexagonal wave is embedded, has been discovered in the southern hemisphere. We propose that the absence of a hexagon in the South Pole is due to the lack of a large-scale anticyclone to force it. A second interesting dynamical feature was the presence of a South Polar Cap, a very small disk with a radius of just 2 deg centered on the pole, dark in the red but bright at blue wavelengths. The red images showed during these years the development and growth of a bright white area surrounding the cap. This suggests a possible radial spread from the pole up to -80 deg, of a newly formed cloud or aerosols, revealing in such a case the existence of intense meridional motions around Saturn's south pole.
Acknowledgements: This work was supported by the Spanish MCYT Plan Nacional de Astronomía y Astrofísica 2000-0932. SPH acknowledges a PhD fellowship from MECD. RGF was supported in part by NASA?s Planetary Geology and Geophysics Program NAG5-10197 and STSCI Grant GO-08660.01A.
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Bulletin of the American Astronomical Society, 34, #3< br> © 2002. The American Astronomical Soceity.