DETECTION OF THE N-II! 122 AND 205 MICRON LINES - DENSITIES IN G333.6-0.2

We present measurements of the G333.6-0.2 H II region which include th e first detection of the N II! 122 mum forbidden line in an astronomi cal source and the first measurement of the N II! 205 mum forbidden l ine in a discrete source. Eleven other fine structure lines of S III! , Fe III!, Si II!, Ne III!, O III!, N III!, O I!, and C II! fro m 19 to 206 mum were also measured along with their adjacent continua. The 122 mum/205 mum flux ratio yields an electron density for the Nzone of log N(e) = 2.5(+0.5/-0.4). From the S III! (19 and 33 mum) an d O III! (52 and 88 mum) line pairs, the electron densities for the O ++ and S++ zones are equal and higher than the N+ region, with log N(e ) = 3.7 +/- 0.1. The density difference between the O III!-S III! an d the N II! emitting regions cannot persist for times comparable to t he stellar evolution time scales without some regeneration mechanism f or the inhomogeneities. The N III! (57 mum) line suggests that the em itting mass in our beam is equally divided between the N+ and N++ regi ons, but we cannot determine a total nitrogen abundance because the N ii! emission is likely to be more extended than our beam. From the S III! to O III! line flux ratio, we infer a stellar effective tempera ture of approximately 36,000 K for stellar atmospheres which roughly c orrespond to main-sequence stars. As with other H II regions of simila r excitation, the theoretical stellar spectrum must be increased signi ficantly at energies greater than the 41 eV ionization potential of Ne + to produce the observed Ne III! (36 mum) line flux. From the O I! (63 and 145 mum) and C II! (158 mum) line fluxes, and our measured in frared continuum luminosity of approximately 1.3 x 10(6) L., the densi ty of the atomic gas adjacent to the ionized region is log N = 4.6. Th is implies that the ionized and neutral regions are in approximate pre ssure e librium.