Hotei Arcus And Western Xanadu, Titan: Evidence For Cryovolcanic Activity From Radar
Résumé
Several surface features interpreted as cryovolcanic in origin have been observed on Titan's surface by both Cassini's RADAR (in SAR mode) and VIMS instruments throughout the Cassini prime mission. The Titan flyby T41 of 22 February 2008 includes a SAR image of part of Hotei Arcus, a semi-circular albedo feature, some 650 km in length along the arc, centered at 26S 79W. A second SAR image of Hotei was acquired May 12, 2008 on flyby T43. These images show that the arcuate southern boundary of Hotei, also seen in ISS data, appears somewhat mountainous in the SAR imagery, and 5 distinct narrow channels, presumably fluvial, flow radially inwards. In the center of the arc, the images reveal lobate, flowlike features that embay surrounding terrains and the channels. Analysis of these features suggest that they are of cryovolcanic origin and younger than surrounding terrain. Their appearance is superficially similar to a region in western Xanadu at 10S 140W imaged by RADAR on flyby T13, on Apr 30, 2006. These two regions are morphologically unlike most of the other cryovolcanic regions so far seen on Titan. Both regions correspond to those identified by the Cassini VIMS as having anomalous and variable infrared brightness, probably due to recent cryovolcanic activity. The RADAR images provide morphological evidence that is consistent with cryovolcanism.