Program: GS-2007B-Q-19

We will use Michelle on Gemini North and T-ReCS on Gemini South to obtain high resolution mid-infrared (8--18.5\,$\mu$m) images of a sample of T Tauri and Herbig Ae disks that have apparently photospheric SEDs below $8\,\mu$m and a bright bump at mid- and far-infrared wavelengths. This has been inferred as a signature of the presence of inner gaps, possibly carved out by newly formed planets, but could also indicate that transiently heated very small grains (VSGs) in the circumstellar environment on 100 AU scales dominate the mid-infrared emission. The emission spectrum of VSGs is independent of distance to the star, causing the mid-infrared images to be much more extended than those from thermal grains. Therefore, imaging in addition to spectral information is required in order to distinguish disks dominated by VSGs from those with bona-fide inner gaps. Recent results from Spitzer and the mid-infrared imager on the VLT, VISIR, have shown the presence of bright, extended emission from VSGs around several T Tauri and Herbig Ae stars, while the SMA has found inner gaps in thermal submillimeter emission. High resolution mid-infrared images from the Gemini telescopes of disks with gap-like SEDs will be able to search for extended emission from VSGs and resolve the largest predicted gaps for a larger sample of nearby proto-planetary disks.