THE HEIGHT OF IONIZED-GAS IN THE INNER GALAXY

The distribution of diffuse [N II] 205 mu m emission perpendicular to the Galactic plane at l = 7.degrees 28 is presented and compared with that of the [C II] 158 mu m emission. The profile of [N II] emission, characteristic of warm ionized gas, is modeled as a Gaussian with a 13 .3(-3.3)(+4.2) arcminutes half-width at half-maximum (HWHM), apparentl y narrower than the 21.9(-1.0)(+1.1) arcminutes HWHM of the distributi on of [C II] 158 mu m emission. The contribution of ionized gas close to the Galactic plane and traced by these observations accounts for 10 %-30% of the [N II] line emission observed by COBE FIRAS. The average ionizing flux derived for the inner Galaxy is consistent with the loca l hydrogen recombination rate. [N II] 205 mu m emission was also detec ted from DR 21. The contribution of compact H II regions to the total Galactic luminosity of [N II] is discussed.