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 interferometry 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 extrasolar planets, despite mass detection limits as low as 7 Mjup, 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.
Copyright 2009 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in AIP Conference Proceedings, Vol. 1094, p. 453-456) and may be found at http://dx.doi.org/10.1063/1.3099145.