2001ApJ...563..889H

High-resolution spectroscopic data of the very compact planetary nebula IC 5117 were obtained in optical wavelengths of 3700-10050 Å with the Hamilton Echelle Spectrograph at the Lick Observatory and have been analyzed along with the International Ultraviolet Explorer UV archive data. Although a diagnostic diagram shows significant density and temperature fluctuations, our analysis indicates that the nebular gas may be represented by a homogeneous shell of extremely high-density gas, N_ε∼90,000 cm^–3. The average electron temperatures, e.g., indicated by the [O III] diagnostics, are around 12,000 K. We construct a photoionization model to represent most of the observed line intensities and the physical condition of this compact nebulosity. Based on the semiempirical ionization correction approach and model indications, we derived the elemental abundances; He, C, N, O, Ne, and Ar appear to be normal or marginally depleted compared to the average planetary nebula, while the remaining elements S, Cl, and K appear to be enhanced. IC 5117 is perhaps a very young compact planetary nebula, slightly more evolved than the other well-known compact planetary nebula IC 4997. The central stellar temperature is likely to be around 120,000 K, evolved from a C-rich asymptotic giant branch progenitor.