M57, The "Ring" Nebula
M57 Ring Nebula Closeup - May 2021
Planewave CDK12.5 - AIS6200MM - LRGB filters - AP1100GTO
Thanks to John McDonald, Joe Carr, and Brock Johnston for their help in processing. However, the mistakes are all my own.
Summer is here, and so is the constellation Lyra, and at the centre of this image, the M57 planetary nebula, aka "The Ring Nebula". This nebula is both very pretty and interesting, as it provides a glimpse of what is likely to be the fate of our own sun. (note that the descripter "planetary" is a misnomer. It doesn't have anything to do with planets, other than the now white dwarf star at the centre of, and illuminating the nebula, is now about terrestrial planet sized). The bright colours of the nova are provided by, in turn, blue heilum in the middle, blue/green oxygen becoming white as it transitions to red nitrogen. Hydrogen is finally responsible for the outer halo of the nebula.
The nebula is very bright (mag 8.8 visually), but also very small (1.4' x 1'), lying between 1500 and 4100 light years away. The nebula is also expanding away from its central, illuminating, star at about 25 km/s and is currently less than a light-year across.