[O Ⅴ] in the Ultraviolet Spectra of Gaseous Nebulae

摘要

Theoretical O V electron-densitysensitive emission line ratios for R = I(2s~2 ~1S_0- 2s2p ~3P_2)/I(2s~2 ~1S_0 -2s2p ~3P_1) are presented. Inspection of Goddard High Resolution Spectrograph Hubble Space Telescope spectra of RR Tel reveals the presence of the [O V] 2s~2 ~1S - 2s2p ~3P_2 line at 1213.80 ?, which is 4.62 + - 0.12 ? away from the 2s~2 ~1S - 2s2p ~3P_2 intercombination transition at 1218.42 ?, in good agreement with the theoretical prediction of Δλ= 4.54 ?. The resultant value of R = 0.82 + - 0.11 implies a logarithmic electron density, log N_e, of 5.2 ± 0.2 cm~-3, in good agreement with that found from other ions with high electron temperature, such as Ne VI, which also provides support for the identification.