Poster title: Seasonal variation of radial brightness contrast of Saturn's rings viewed in mid-infrared by Subaru/COMICS

Poster abstract: To investigate the mid-infrared (MIR) characteristics of Saturn’s rings, we collected and analyzed MIR 
high spatial resolution images of Saturn’s rings obtained in January 2008 and April 2005 with COMICS mounted on 
Subaru Telescope, and investigated the spatial variation in the surface brightness of the rings in multiple bands in the MIR. 
We also composed the spectral energy distributions (SEDs) of the C, B, and A rings and the Cassini Division, and 
estimated the temperatures of the rings from the SEDs assuming the optical depths. We find that the C ring and the 
Cassini Division were warmer than the B and A rings in 2008, which could be accounted for by their lower albedos, lower 
optical depths, and smaller self-shadowing effect. We also find that the the C ring and the Cassini Division were 
considerably brighter than the B and A rings in the MIR in 2008 and the radial contrast of the ring brightness is the inverse 
of that in 2005, which is interpreted as a result of a seasonal effect with changing elevations of the sun and observer 
above the ring plane.