Long-Slit Spectroscopy of IC 5135 and NGC 4388

The nucleus of the peculiar Sa galaxy IC 5135 has strong emission lines whose relative intensities resemble those of Seyfert 2 galaxies (Phillips, Charles, and Baldwin 1983). However, the galaxy exhibits relative line intensities such as [O III] λ5007/H β = 6.5 and He II λ4686/H β = 0.17 that are considerably smaller than typical Seyfert 2 values of 11 and 0.3, respectively (Koski 1978). New, high-resolution spectra (FWHM ≈ 2Å) obtained at Las Campanas Observatory reveal that the H β emission-line profile actually consists of a relatively strong, narrow component (FWHM ≈ 250 km s −1 ) superposed on a much weaker, broad base (FWHM ≈ 1000 km s −1 ; Fig. 1). A similar two-component profile is evident in [O I] λ6300, whose narrow core probably comes from circumnuclear H II regions that produce little [O III] and He II emission. The strong, high-order Balmer absorption lines are consistent with the presence of a young stellar population in the nucleus.