IONIZED-GAS IN SAGITTARIUS-B2 MAIN ON SCALES OF 0.065 ARCSECONDS (600AU)

The ionized gas in the Sagittarius B2 Main star-forming region has bee n imaged with similar to 65 mas (600 AU) resolution using the Very Lar ge Array (VLA) at 7 mm in the A configuration. These observations have similar to 4-5 times the resolution of the previous highest resolutio n images of this source. These VLA observations show that the central four ultracompact H II (UC H II) regions in Sgr B2 Main (F1, F2, F3, a nd F4) break up into similar to 20 separate UC H II regions. The indiv idual sources have small resolved sizes (similar to 10(-3) pc), high d erived emission measures (EM similar to 10(9) pc cm(-6)), and high rms electron densities (n(e) similar to 10(6) cm(-3)). We compare the obs erved radius and derived emission measure of each of these regions wit h those expected for a UC H II region in pressure equilibrium with its environment, using previously published temperatures and densities fo r the Sgr B2 molecular core (n(H2) = 2 x 10(7) cm(-3)). We find that t he observed emission measures are in fact higher than those predicted in a simple pressure-confinement model, suggesting that the molecular densities on scales that confine the UC H II regions may be higher tha n 2 x 10(7) cm(-3).