Electron densities for six planetary nebulae and HM SGE derived fromthe CIII lambda 1907/1909 ratio.
Feibelman, W. A.; Hobbs, R. W.; Boggess, A.; McCracken, C. W.
United States
Abstract
Electron densities for IC 418, NGC 6572, IC 1297, NGC 3242, NGC 6818, NYC 3211, and HM Sagittae derived from high-dispersion IUE C III] spectrograms are consistently higher than those derived from either surface brightness measurements or forbidden line intensity ratios in the visible. The nebulae were selected for a range of excitation classes from 3 to 9. Line splitting due to expansion velocities is observed for three objects. The great width of the λ1909 C III] line in MM Sagittae suggests large expansion velocities.