Figure 1 - Iron 'bar'

A composite RGB image of the Ring Nebula (also known as Messier 57 and NGC 6720) constructed from four WEAVE/LIFU emission-line images. The bright outer ring is made up of light emitted by three different ions of oxygen, while the ‘bar’ across the middle is due to light emitted by a plasma of four-times-ionised iron atoms. North is up and East is to the left in the image.