IC443 - A Thermal Composite Remnant

This thermal composite remnant is a cross between a shell-like (http://heasarc.gsfc.nasa.gov/docs/objects/snrs/shell-like.html) and Crab-like (http://heasarc.gsfc.nasa.gov/docs/objects/snrs/crab-like.html) remnant. To an x-ray astronomer, a composite remnant is one which shows shell- type emission in the radio and plerionic emission in the x-ray. An example of this type of remnant is IC 433.html (below). In this image, red shows radio emission and blue shows X-ray emission. Theory usually predicts that the dominant X-ray emission would be found on the outside rim of the remnant, where the forward shock is located.

The spectrum of the x-rays from the center are thermal, or line dominated.

(Image courtesy of Jonathan Keohane (http://lheawww.gsfc.nasa.gov/users/jonathan/home_page.html)).