  In the BPT diagram, the distribution of the emission-line galaxies from the
Sloan Digital Sky Survey (SDSS) evokes the wings of a seagull. Traditionally,
galaxies in the right wing are considered to host AGNs. Our study of the
stellar populations of SDSS galaxies showed that about1/4 of galaxies thought
to host LINERS are in fact "retired galaxies", i.e. galaxies that stopped
forming stars and are ionized by hot post-AGB stars and white dwarfs (Stasinska
et al. 2008). When including the galaxies that lack some of the lines needed to
place them in the BPT diagram the fraction of retired galaxies is even larger
(Cid Fernandes et al., 2009, arXiv:0912.1376)
