The Optical Spectrum of Vela X

Abstract

The optical spectra of two filaments in the nebula Stromlo 16 (the radio source Vela X) were obtained with the photoelectric spectrum scanner. Electron temperature stratification over the filaments has been deduced from the intensity ratios between certain lines in these spectra. Indications are of a small-sized high temperature region with an electron temperature Te ~ 10· oK together with a much greater volume of cooler gas with Te ~ 10' oK. The former region is bright in the lines of OIlI whilst the latter region is bright in the lower excitation lines of OIl, Il, and H. The collisionally excited nature of these spectra confirms previous conclusions that this object is the remnant of a supernova.