Optical Slitless Spectroscopy of Large Magellanic Cloud Planetary Nebulae: A Study of the Emission Lines and Morphology*

摘要

Hubble Space Telescope Space Telescope Imaging Spectrograph slitless spectroscopy of LMC planetary nebulae (PNs) is the ideal tool to study their morphology and their ionization structures at once. We present the results from a group of 29 PNs that have been spatially resolved, for the first time, in all the major optical lines. Images in the light of Hα, [N II], and [O III] are presented, together with line intensities, measured from the extracted one- and two-dimensional spectra. A study on the surface brightness in the different optical lines, the electron densities, the ionized masses, the excitation classes, and the extinction follows, illustrating an ideal consistence with the previous results found by us on LMC PNs. In particular, we find the surface brightness decline with the photometric radius to be the same in most emission lines. We find that asymmetric PNs form a well-defined cooling sequence in the excitation-surface brightness plane, confirming their different origin and larger progenitor mass.