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F. Marchis (UC-Berkeley/CfAO), I. de Pater (UC Berkeley), T. Fusco (ONERA), A. Davies (JPL), H. Roe (UC Berkeley), D. Le Mignant (Keck Obs.), B. Macintosh (LLNL), R. Prangé (IAS)
Io has been observed with the Keck-10m Adaptive Optics (AO) system facility on 3 nights in February 2001 with the the near-infrared camera NIRSPEC. The sharpness of the images has been enhanced applying the MISTRAL deconvolution process (Conan et al., SPIE, 4007, 913, 2000), an algorithm especially made for planetary object observations with AO systems, leading to a spatial resolution of ~130 km. These high-resolution data revealed the presence of several bright hot spots, easily detectable on the sunlit image. On February 19 2001, two bright emission areas corresponding to Amirani and Tvashtar were detected on images with a Sub-Earth-Point (SEP) of ~110 degree. The H/K ratio indicates a temperature of 1030±30 K for Amirani and 850±15 K for Tvashtar.
On February 22, the region to the northwest of Loki reveals a very bright outburst in all three JHK bands. The hot spot, located at (41±4 N, 340±4 W), corresponds to the Surt hot spot, a sporadic active area last seen in October 1996. From the 3 JHK broad bands, plus 2 narrow bands, photometry we deduced that the emission is produced by an area of 520 km2 with a T~900K and a smaller area of 27 km2 with a T~1500 K. Accurate analysis of 20 February data showed that we detected the beginning of the eruption, characterized by a emission area with a radius of a few meters and a T~1400±150 K. A complete analysis of this eruption, using a silicate cooling flow model (Davies et al., Icarus, 148, 211,2000) will be also presented.
This work has been supported in part by the National Science Foundation Science and Technology Center for Adaptive Optics, managed by the University of California at Santa Cruz under cooperative agreement No. AST-9876783
The author(s) of this abstract have provided an email address for comments about the abstract: fmarchis@astron.berkeley.edu