Temperature variations and N/O in the Orion nebula from HST observations

摘要

Using the Goddard High Resolution Spectrograph (GHRS) and the Faint Object Spectrograph (FOS) on the Hubble Space Telescope, we measured the flux of the N II ](2s2p~3~5S_2 → 2s~2s2p~2~3P_2,1) lines at λ_vac = 2143.45, 2139.68 A in the Orion Nebula - the first detection of these lines in an H II region. In order to assess the N+/O+ ratio, we also measured the flux of the [O II] (2p~3~2p~0_1/2,3/2 →2p~3~4S~0_3/2) lines at λ_vac = 2471.05, 2471.12 A. in addition, with the FOS, other emission lines were measured in the same aperture in order to assess the average electron temperature and mean-square temperature variation(t~2) in the N+ region, as ell as the N+/O+ ratio.