HIGH ANGULAR RESOLUTION FAR-INFRARED OBSERVATIONS OF SAGITTARIUS-B2

We have observed the continuum emission from the Sagittarius B2 molecular cloud core using eight-channel 50 and 100-mu-m photometers mounted at the f/12 true Cassegrain focus of the 0.9 m telescope of the Kuiper Airborne Observatory. The data have been deconvolved using a one-dimensional maximum entropy technique to produce images with angular resolution of 20" x 7" at 50-mu-m and 28" x 10" at 100-mu-m. Despite its greater column density, determined from millimeter and submillimeter observations, the northern source Sgr B2 (N) is observed to have a flux density of only 1.5 kJy at 50-mu-m, compared to 4.3 kJy for Sgr B2 (M). This confirms previous models with very large extinction in front of the northern source and total luminosity for Sgr B2 of 1-2 x 10(7) L.. Sgr B2 (N) and Sgr B2 (S) are here detected as separate sources for the first time in the far-infrared region. We find evidence for a significantly spatially extended component of the far-infrared emission at 50 and 100-mu-m wavelength, which has an angular extent of 1' x 2'. Its approximate spatial coincidence with a low-level extended component of the radio free-free emission and with the portion of the Sgr B2 core having densities greater-than-or-equal-to 10(5) cm-3 derived from molecular observations suggests that the ionizing radiation from the massive stars in the compact sources is diffusing through a region with a beam-averaged visual extinction greater than or equal to a few hundred mag. This strongly implies that the gas and the dust in the central portion of the cloud surrounding the compact radio free-free/far-IR sources are highly clumped.