Spatial Variations in UV-Optical Lines Across the Ring Nebula

Extract

IUE spectra of the Ring Nebula (M57=NGC 6720) were taken 16–18 May 1991 using the large aperture (10 × 20 arc sec oval) at low dispersion. SWP and LWP spectra of seven locations were acquired at 10 arc sec intervals extending along a PA = 124° line and passing through the central star of the nebula. This direction was such that the long axis of the large aperture was aligned and overlapped, thus enabling the line profiles to be “spliced” together. This provided continuous spatial variation curves at approximately 1 arc sec spatial resolution over the entire diameter (80 arc sec) of the main body of the Ring Nebula.