Jellyfish (IC 443)

Object Type: Supernova Remnant
Scope: Orion APO 80mm; Exposure 200 minutes.

IC 443 (the Jellyfish Nebula, Sharpless 248) is a supernova remnant in Gemini, near the star Eta Geminorum, about 5,000 light-years away and roughly 70 light-years across. It is the debris of a massive star that exploded somewhere between about 3,000 and 30,000 years ago; the same event left behind the neutron star CXOU J061705.3+222127, seen near the remnant's southern rim. IC 443 is one of the best-studied cases of a supernova remnant colliding with surrounding molecular clouds: its shock wave is decelerating against a dense cloud to the southeast (traced by OH maser emission and a coincident gamma-ray source) while racing faster into thinner gas to the northeast. A giant foreground molecular cloud crossing the remnant heavily absorbs its light.