IC 443, the Jellyfish Nebula, is a supernova remnant in Gemini colliding with a molecular cloud, one of the sites that showed remnants make cosmic rays.
At a glance
| type | supernova remnant |
|---|---|
| distance from the Sun | 6,200 light-years (1.9 kpc) |
| its light left it | 6,200 years ago |
| size in the piece | about 65 light-years acrossmodel |
Read off the piece’s own catalogue, the same values it draws with. Model marks a property of the piece’s galaxy model rather than a measurement.
About IC 443
IC 443 lies near the feet of Gemini, and its curved, bright edge and trailing filaments give it the look of a jellyfish. On one side the blast wave is running into a dense molecular cloud, and the collision heats and compresses the gas, which glows in infrared and molecular lines.
Where accelerated protons from the shock hit the dense gas, they produce particles that decay into gamma rays of a characteristic spectrum. The Fermi telescope detected that signature here and in W44, the clearest evidence that supernova remnants accelerate the protons that make up most cosmic rays.
A neutron star with its own small wind nebula sits near the southern edge, probably the core of the star that exploded.
What you see in the piece
It is drawn as a shell of shocked gas whose skin is ripped where the blast meets denser gas; it shows best in the radio band, and in gamma rays where cosmic rays hit the cloud.
Measured or modelled
Its age is uncertain; estimates differ widely. Whether the neutron star belongs to it is likely but not certain. The drawn extent is modelled.
Questions
Why is IC 443 called the Jellyfish Nebula?
Its bright curved rim and the fainter filaments trailing from it resemble a jellyfish in photographs.
How far away is IC 443?
IC 443 is about 6,200 light-years (1.9 kpc) from the Sun, in Gemini.