The Jellyfish Nebula IC 443 is a supernova remnant (SNR) in the constellation Gemini, which is located near the 3rd magnitude star η Geminorum (near the right edge of the image). It is about 5,000 light years distant from Earth. IC 443 is a large SNR, having an angular diameter of 50 arcmin with a shell-like morphology. The supernova explosion which produced the nebula has occurred up to 30,000 years ago. The SNR emits X-rays which are produced by a neutron star hidden within the nebula, which is likely the collapsed remnant of the core of the original star which exploded in the supernova. IC 443 is heavily interacting with surrounding molecular clouds.
The nebulosity emits all of its light in isolated emission lines. The most prominent of those are the Hα, [OIII] and [SII] lines, which were exclusively recorded to obtain the image shown above. This is a "natural color" composition mixed so that the resulting colors are close to the visible spectrum of the human eye. The following mixture was used:
Gemini, zoom lens photograph.
IC 443 - Jellyfish Nebula in Hα, which is part of this image.
IC 443 - Jellyfish Nebula in [OIII], which is part of this image.
IC 443 - Jellyfish Nebula in [SII], which is part of this image.