The nature of ionized gas in early-type galaxies
  We present a study of the ionized gas in a sample of 65 nearby early-type
galaxies, for which we have acquired optical intermediate-resolution spectra.
Emission lines are detected in ~89 % of the sample. The incidence of emission
appears independent from the E or S0 morphological classes. According to
classical diagnostic diagrams, the majority of the galaxies are LINERs.
However, the galaxies tend to move toward the "Composites" region (at lower
[NII]/Halpha values) as the emission lines are measured at larger
galacto-centric distances. This suggests that different ionization mechanisms
may be at work in LINERs.
