This is the veil nebula, about 1500-2000 light years away.
Total exposure length; 8.5 hours.
The remnants of a supernova that exploded 10.000-20.000 years ago.
Taken with a dedicated astrophotography black&white camera, using specificl filters to capture the wavelengths of light from the different gasses in the nebula. Oxygen, Hydrogen, Sulphur.
These 3 layers get combined in the the R, B, G to create the final colour image.
Hydrogen = green channel
Oxygen = blue channel
Sulphur = Red channel.
(This is the same method that the Hubble uses to create its images)