Searching for Young Planets with Sparse Aperture Masking

We describe an ongoing survey to directly detect substellar and planetary companions to nearby young stars. This survey uses adaptive optics and nonredundant aperture-masking inter-ferometry to achieve typical contrast limits of ΔK~6 at the diffraction limit, probing a completely new regime of parameter space. These observations have revealed many new stellar companions, but only a few companions that might be brown dwarfs; this paucity resembles the so-called "brown dwarf desert" that has been observed by RV planet searches. The survey has not detected any extra-solar planets, despite mass detection limits as low as 7 M_(Jup), yielding constraints on the population of extrasolar giant planets. Finally, we discuss some of the implications for protoplanetary disk evolution, including potential sources for gap formation and disk dissipation.