We have discovered that the classical T Tauri star GW Ori is a spectroscopic binary with an orbital period of 242 days. For a primary mass of 2.5 M., the secondary mass is likely between 0.5 M. and 1M., and the primary/secondary separation is slightly more than 1 AU. The measured eccentricity of the GW Ori orbit is not distinguishable from zero (e = 0.04 +/- 0.06), although the measurement error is fairly large. The center-of-mass velocity has been observed to vary over a period of 1000 days, suggesting the presence of a third star in the system or an m = 1 perturbation in the associated disk. The observed spectral energy distribution of GW Ori shows a large near- and far-infrared excess over the stellar photosphere. The morphology of the spectral energy distribution is double peaked with a minimum in the continuum near 10-mu-m; in addition there is a very strong 10-mu-m silicate emission feature. We have considered two theoretical models for the GW Ori system. A circumstellar disk around the primary star will have a gap which is tidally driven by the companion star. Our pure-disk model thus consists of a primary star, a circumprimary disk, a circumbinary disk, and optically thin hot dust in the gap between the two disks. Such a model, with a gap between 0.17 and 3.3 AU, provides a good fit to the observed spectral energy distribution, with the exception of a steep rise in observed luminosity from 13 to 18-mu-m. The independently determined radius of the secondary orbit falls within this gap, and the width of the gap is dynamically plausible albeit somewhat large. In this model, the disk components must produce 34L.. A large accretion rate (almost-equal-to 5 X 10(-6) M. yr-1) is required, with no evident boundary layer emission, and the details of the disk luminosity production remain uncertain. We have considered a second model which replaces the active circumbinary disk with an optically thin shell that reprocesses stellar luminosity into the far infrared. Such a shell is motivated as residual infall and requires an inner radius of order 100 AU. This disk-shell model provides a good fit to the observed spectral energy distribution and somewhat relieves the energy demands on the disk. However, in order to produce the observed far-infrared luminosity, the visual extinction of the shell must be about 2 mag, which is larger than the observed A-upsilon = 0.82 mag. Additional assumptions regarding our line of sight to GW Ori are thus required. A circular orbit for a 242 day period binary would be notable given the rarity of circular orbits among long-period main-sequence binaries. We discuss the significance of the possible circular orbit of GW Ori with respect to the excitation of eccentricity in binary orbits by disks.
