Jellyfish Nebula and S249 Nebula

The Jellyfish Nebula (IC 443) is a supernova remnant (SNR) of a massive star that exploded 3,000 to 30,000 years ago in the constellation Gemini. It's 70 light years across and about 5,000 light years from Earth. IC 443 is an extended source, having an angular diameter of 50 arcmin (by comparison, the full moon is 30 arcmin across). The SNR is interacting with the surrounding molecular clouds and is one of the most studied supernova remnants in the sky. The supernova event produced the nebula and a neutron star. The presence of the neutron star and the nebula’s location in a star forming region indicate that the remnant was created by a Type II supernova, one triggered by a rapid collapse and violent explosion of a star with a mass at least 8 times that of the Sun. The neutron star is moving away from the site at about 800,000 km/h.
the nebula appears shell-like and is composed of two sub-shells with different radii, emissions and centres. The larger northeastern shell was likely created by a shock wave travelling at about 100 km/s. It consists of complex filaments that are emitting light from iron, neon, silicon and oxygen atoms and dust particles, which are heated by the blast from the supernova event. The smaller southern shell, which was probably created by a shock wave moving at about 30 km/s, is composed of denser clumps that emit light mainly from hydrogen gas and hot dust. There is a third shell which is larger but, even though it was once believed to be part of the Jellyfish Nebula, it is now known to be older, with an estimated age of about 100,000 years. The larger shell is part of a different supernova remnant
The stars η (right) and μ (left) Geminorum, the diffuse emission from S249 (north), and the G189.6+3.3 partial shell (center) are visible.