A circumstellar dust disk around T Tauri N: Subarcsecond imaging at lambda= 3 millimeters

We present high-resolution imaging of the young binary T Tauri in continuum emission at lambda = 3 mm. Compact dust emission with integrated flux dens ity 50 +/- 6 mJy is resolved in an aperture synthesis map at 0." 5 resoluti on and is centered at the position of the optically visible component, T Ta u N. No emission above a 3 a level of 9 mJy is detected 0." 7 south of T Ta u N at the position of the infrared companion, T Tau S. We interpret the co ntinuum detection as arising from a circumstellar disk around T Tau N, and estimate its properties by fitting a flat-disk model to visibilities at lam bda = 1 and 3 mm, and to the flux density at lambda = 7 mm. Given the data, probability distributions are calculated for values of the free parameters , including the temperature, density, dust opacity, and disk outer radius. The radial variation in temperature and density is not narrowly constrained by the data. The most likely value of the frequency dependence of the dust opacity, beta = 0.53(-0.17)(+0.27), is consistent with that of disks aroun d other single T Tauri stars in which grain growth is believed to have take n place. The outer radius, R = 41(-14)(+26) AU, is smaller than the project ed separation between T Tau N and T Tau S, and may indicate tidal or resona nce truncation of the disk by T Tau S. The total mass estimated for the dis k, log (M-D/M.) = -2.4(-0.6)(+0.7), is similar to masses observed around ma ny single pre-main-sequence sources and, within the uncertainties, is simil ar to the minimum nebular mass required to form a planetary system like our own. This observation strongly suggests that the presence of a binary comp anion does not rule out the possibility of formation of a sizable planetary system.