1996PASP..108..488A

International Ultraviolet Explorer (IUE) and optical region spectroscopic observations are presented for the medium excitation planetary nebula (PN), NGC 6790, which displays a rich spectrum permitting application of several diagnostic ratios and the calculation of a number of ionic concentrations, N(ion)/N(H+). NGC 6790 seems to be a relatively young object which may represent a stage of development only slightly beyond that of a PN such as Hb 12. The diagnostics for NGC 6790 suggest a rather large density range, althought not one as great as that found in IC 4997. An attempt is made to calculate a plausible simpel spherically symmetrical model. We suggest that NGC 6790 may serve as a prototype "standard" for PN of intermediate age, density, and evolutionary development. Further modeling attempts would appear inappropriate until images of high spatial resolution become available.