HIGH-IONIZATION NUCLEAR EMISSION-LINE REGION IN THE SEYFERT-GALAXY TOLOLO-0109-383

We present a detailed optical spectroscopic analysis of the high-ioniz ation Seyfert galaxy Tololo 0109-383, which was classified originally as a type 2 Seyfert nucleus. The high-ionization nuclear emission-line region (HINER) (traced by e.g., [Fe x] lambda 6374) of this galaxy is found to be spatially extended. Although the total radial extent of t he HINER amounts to similar to 1.1 kpc, similar to 70% of the HINER em ission is concentrated in the inner 220 pc in radius. The inner HINER in Tololo 0109-383 can be interpreted by the photoionization model of Ferguson, Korista, & Ferland, while the extended HINER suggests that l ow-density interstellar medium is also photoionized by high-energy con tinuum emission as described by Korista & Ferland. We find an extended low-ionization emission line region traced by H alpha, [N II], and [S II] emission lines with very narrow widths (< 200 km s(-1)) at simila r to 2.2 kpc east of the nucleus. This region is characterized by (1) the observed [N II]/H alpha ratio, which is similar to 0.8; (2) no mea surable [O III] emission; and (3) a low ionization parameter, U simila r to 6 x 10(-5). These properties can also be interpreted in terms of a photoionization model. As well as confirmation of the presence of br oad emission in both Ha and HE lines, we also find optical Fe II emiss ion features in our spectra. Since the optical Fe II emission is one o f the important characteristics of type 1 active galactic nuclei, it i s shown that Tololo 0109-383 harbors a type 1 central engine in its nu cleus. Since the soft X-ray-to-infrared (60 mu m) luminosity ratio of Tololo 0109-383 is higher than those of typical type 2 Segfert nuclei, we consider that blocking by a dusty torus may be incomplete and thus we are able to observe the type 1 nature of Tololo 0109-383.