Cool Stars 14 - Submitted Abstract # 330 This version created on 05 October 2006 Probing Pre-Planetary Disks at sub-AU Scales with IOTA Closure Phases Rafael Millan-Gabet, Caltech John Monnier, U. Michigan Obs. Grenoble Jean-Philipe Berger W. A. Traub, JPL F. P. Schloerb, U. Massachusetts Amherst E. Pedretti, U. Michigan M. Benisty, Obs. Grenoble N. P. Carleton, SAO P. Haguenauer, ESO P. Kern, Obs. Grenoble P. Labeye, LETI M. G. Lacasse, SAO F. Malbet, Obs. Grenoble K. Perraut, Obs. Grenoble M. Pearlman, SAO N. Thureau, U. Michigan Optical long baseline interferometers operating at near-infrared wavelengths from the ground have in recent years provided direct new views into the inner (sub-AU) regions of pre-planetary disks around young stars. We present new results from the IOTA interferometer, which has recently completed the first survey of young stellar objects using closure phases. These observations directly probe the morphology of the inner disk emission, thus testing models of the detailed physical properties of the disk inner rim. We also present a surprising result for the young star AB Aurigae, for which a closure phase signal appears at larger (few-AU) spatial scales, best modelled as a disk hot-spot, and which, excitingly, could physically correspond to a forming sub-stellar companion. ----------------------------------