Abstract

PHILLIPS, J. P.. The use of line excitation mapping to investigate planetary nebula morphologies. Rev. mex. astron. astrofis [online]. 2004, vol.40, n.2, pp.193-208. ISSN 0185-1101.

It is now well established that circular, elliptical, and bipolar planetary nebulae (PNe) possess differing physical and spatial characteristics. Not only are their structures quite distinct, but they also appear to possess differing Zanstra temperatures, abundances, expansion velocities, brightness temperatures, and scale heights above the Galactic plane. We report here a further sensitive way in which the differences between these outflows may be illustrated. We shall note that the nebulae posses varying ranges of emission line ratio, and that this is likely to arise as a consequence of their differing progenitor masses. Similarly, we point out the potential of line-ratio mapping for analyzing other morphological classes, as well as for establishing the uniqueness of their populations, and their relative progenitor masses. Thus we find that sources containing jets often possess low line emission intensities relative to hydrogen, suggesting that their progenitors may have low overall masses. This conclusion is supported by a variety of independent observational evidence. We also show that irregular sources appear to represent a distinct class of outflows. It is likely that their mean progenitor masses are greater than those of elliptical PNe, but less than those of the bipolar outflows.

Keywords : ISM [Jets and Outflows]; ISM [Lines and Bands]; Planetary Nebulae [General].