In a previous work
(Storchi-Bergmann and
Pastoriza 1989)
we have
studied in detail the spectra of one LINER and five "dwarf" Seyfert 2
galaxies showing nitrogen emission lines [N II]
6548, 6584 very
strong when compared with H
. The
most accepted explanation for high
[N II] / H ratios was that they
were due to the high excitation of the gas
(Pagel 1983).
Our work has shown that the gas abundance also plays
a role in the enhancement of the [N II] /
H ratio; We could reproduce
the highest ratios only with an overabundance of nitrogen in the
nuclear gas relative to the other heavy elements when compared to the
solar value. The abundance of nitrogen in LINERs (although not in
Seyfert 2's) was previously discussed by
Binette (1985),
who has also
found nitrogen over oxygen ratios higher than solar. In our work there
is also an indication that the same is happening with sulfur.
In this work we search for the above effects in a larger sample, using emission-line data from the literature which were compared with shock and photoionization model values.