Optical and infrared interferometry are ideal for studying the small scale characteristics of young stars and their circumstellar material. Early observations with this technique of Herbig Ae/Be, T Tauri and FU Ori stars measured the spatial size of the hot inner edge of the circumstellar disks surrounding these objects and revealed larger than predicted sizes. These results were part of the observational motivation for modified circumstellar disk models in which the inner edge of the dust disk is located at the dust sublimation radius and is vertically extended. The current generation of large aperture interferometers is extending these observations to longer wavelengths and to a much larger sample of objects in both mass and luminosity. I will discuss these recent results and their implications for star and planetary system formation.

Refreshments will be served at 3:30pm in the Steward Observatory Lobby.