Reprocessing in luminous disks

We develop and investigate a procedure that accounts for disk reprocessing of photons that originate in the disk itself. Surface temperatures and simp le, blackbody spectral energy distributions (SEDs) of protostellar disks ar e calculated. In disks that flare with radius, reprocessing of stellar phot ons results in temperature profiles that are not power-law at all radii but are consistently shallower than r(-3/4). Including the disk as a radiation source (as in the case of active accretion) along with the stellar source further flattens the temperature profile. Disks that flare strongly near th e star and then smoothly curve over and become shadowed at some distance (" decreasing curvature" disks) exhibit nearly power-law temperature profiles that result in power-law infrared SEDs with slopes in agreement with typic al observations of young stellar objects. Disk models in which the photosph eric thickness is controlled by the local opacity and in which the temperat ure decreases with radius naturally have this shape. Uniformly flaring mode ls do not match observations as well; progressively stronger reprocessing a t larger radii leads to SEDs that flatten toward the infrared or even have a second peak at the wavelength corresponding (through the Wien law) to the temperature of the outer edge of the disk. In FU Orionis outbursting syste ms, the dominant source of energy is the inner disk. Reprocessing throughou t the disk depends sensitively on the inner disk shape and emitted temperat ure profile. We show that the thermal instability outburst models of Bell & Lin reproduce trends in the observed SEDs of FU Ori systems with T proport ional to r(-3/4) in the inner disk (r less than or similar to 0.25 AU corre sponding to lambda less than or similar to 10 mu m) and T proportional to r (-1/2) in the outer disk. Surface irradiation during outburst and quiescenc e is compared in the region of planet formation (1-10 AU). The contrast bet ween the two phases is diminished by the importance of the reprocessing of photons from the relatively high mass flux, outer disk ((M) over dot = 10(- 5) M. yr(-1)), which is present during both outburst and quiescence.