Nuclear activity in two spiral galaxies with jets : NGC 1097 and 1598.

The barred spiral galaxies NGC 1097 and 1598 are unusual in being known to have optical jet-like features aligned with their nuclei; they also have conspicuous nuclear emission-line spectra which have been studied in some detail in an attempt to throw light on the underlying activity. The very nuclei are either classic 'Liners' (NGC1097) or quite similar to 'Liners's (NGC 1598), and are surrounded by giant H II complexes with typical low excitation H II region spectra. The presence of near solar abundances of N and O in these H II regions, and thus presumably also in the nuclei themselves, supports power law photoionization models for the excitation of 'Liners' in general, in preference to available shock models. Since 'Liner' spectra are now known to be common in galactic nuclei, it is not clear that these results bear any relation to the jets; but it could be of interest to search for more jets in galaxies containing 'Liners' at a deep and uniform level of sensitivity.