A composite RGB image of the Ring Nebula (also known as Messier 57 and NGC 6720) constructed from four WEAVE/LIFU emission-line images (IMAGE)
Caption
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.
Credit
R. Wesson, Cardiff University/UCL
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License
Original content