William D. Langer, Thangasamy Velusamy
Jet Propulsion Laboratory, Caltech

Paul F. Goldsmith
NAIC, Cornell University

We report the detection of emission from gas phase methanol in a protostellar disk in the young, class 0 infrared source located in L1157. Spatially unresolved emission was detected in the 2_k$-1_k transitions of methanol at 3mm using the Caltech Owens Valley Millimeter Array. The fractional abundance of methanol is about 3 x 10^-7 for a flared disk model. Substantial chemical processing probably takes place in the disk via depletion and desorption from grains. The methanol desorbed from the grains in the warm surface layers returns to the icy grain mantles in the cooler interior of the disk, where it is available to become part of the composition of solar system-like bodies, such as comets, formed in the outer circumstellar region. This first millimeter--wavelength detection of a complex organic molecule in a young protostellar disk has implications for disk structure and chemical evolution and for potential use as a gas and dust temperature probe. We discuss the potential of ALMA to improve on such chemical studies in the innermost disk regions. WL and TV's research was conducted at the Jet Propulsion Laboratory, Caltech with support from NASA. The National Astronomy and Ionospheric Center is operated by Cornell University under a cooperative agreement with the National Science Foundation.