Cool Stars 14 - Submitted Abstract # 235 This version created on 05 October 2006 Searching for Metal-Poor L and T Dwarfs: An Adaptive Optics Survey of Cool Subdwarf Stars Christopher Gelino, Spitzer Science Center J. Davy Kirkpatrick, IPAC The spectra of L and T dwarfs can be affected by effective temperature, gravity, and metallicity. Of these, metallicity effects are the most poorly understood because so few L and T dwarfs with known metallicity have been discovered. Those with suspected low metallicity are solitary objects in the field, where their exact metal content is difficult to ascertain. One way to constrain the effects of low metal content in an L or T dwarf atmosphere is to find L or T dwarfs as companions to stars with known metal-poor atmospheres (as determined by much more mature stellar atmosphere models). To this end we have conducted an adaptive optics survey of ~50 cool subdwarf stars with the Keck telescope to search for very low-mass companions. We present the preliminary results of this survey and discuss the binarity fraction of our sample and the prospects of finding metal-poor L and T dwarf companions. ----------------------------------