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. Full description
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.
RGB key:- Red: the bar-shaped emission from four-times-ionized iron atoms in the [Fe V] spectral line at a wavelength of 4227 Angstrom (422.7 nm). Also shown in red, in the main ring, is emission in the [O I] 6300 Angstrom auroral line produced by neutral oxygen atoms. Green: emission in the [O II] 3727 Angstrom line pair emitted by singly-ionized oxygen atoms. Blue: emission in the [O III] 4959 Angstrom line of doubly-ionized oxygen atoms.
The angular dimensions of the image are 120 x 110 arcseconds on the sky (E-W x N-S), corresponding to physical dimensions of 95,000 x 87,000 Astronomical Units (AU) for the 787 parsec distance to the Ring Nebula. An Astronomical Unit is the mean distance from the Sun to the Earth.
