SIMBAD references

A study of IUE archival low-dispersion spectra was conducted in an attempt to correlate the C IV/He II and C III]/C IV emission line ratios as indicators of x-ray emission in planetary nebulae. The presence of P Cygni lines revealed a strong correlation for planetaries known to exhibit x-ray emission. Of the twelve planetaries definitely known to emit x-rays, eleven have been observed with IUE and all but one show ultraviolet lines with very strong P Cygni profiles for at least one, and sometimes all, of the N V, O V, or C IV lines which are indicative of strong stellar winds. Twenty planetary nebulae are identified as likely candidates for x-ray sources, based on their high IUE emission line flux ratios for C IV/He II as well as prevelance of P Cygni lines. Some misconceptions based on outdated IUE data are corrected.