Both optical and X-ray emission are heavily absorbed by a giant molecular cloud in the foreground, crossing the whole remnant body from northwest to southeast.

Recent Chandra[6] and XMM-Newton[7] observations identified a plerion nebula, close to the remnant southern rim.

Massive stars are known to be short lived (roughly 30 million years), ending their life when they are still embedded within the progenitor cloud.

The more massive stars (O-type) probably clear the circum-stellar environment by powerful stellar winds or photoionizing radiation.

In the southeast the blast wave is interacting with a very dense (~10,000 cm−3) and clumpy molecular cloud, such that the emitting shocked gas has a ring-like shape.

[10] OH (1720 MHz) maser emission, which is a robust tracer of interaction between SNRs and dense molecular clouds, has been detected in this region.

[11] A source of gamma-ray radiation[12] is spatially coincident with IC 443 and the maser emission region, though is not well understood whether it is physically associated with the remnant or not.

The forward shock has encountered a wall of neutral hydrogen (HI), and is propagating into a less dense medium (~10-1,000 cm−3) with a much higher velocity (80–100 km s−1)[10] than in the southern ridge.