ON THE SULFUR AND NITROGEN ABUNDANCES IN THE NUCLEUS OF SEYFERT-2 AND LINER GALAXIES

We study the gas abundance in Seyfert 2 and LINER nuclei using optical emission-line data for a sample of 177 galaxies obtained from the literature. On the basis of photoionization model results it is shown that the range presented by the emission-line ratios [S II]/H-alpha and [N II]/H-alpha can only be reproduced by a range in sulfur and nitrogen abundances from half-solar to five times solar. The abundances of these two elements seem to be correlated. It is also shown that, if the apertures are small enough, the observed [S II]/H-alpha values indicate overabundance of sulfur for most Seyfert 2 and LINER nuclei. A similar result has been previously found for nitrogen.