Saturday, 23-Sep-2017 09:27:39 GMT
Cass A is a supernova remnant in our own Galaxy. This is the remnant of a star which exploded in ???? Since then, the material thrown off in the explosion has been expanding and interacting with the surrounding gas. It is this interaction which produces the fine structure seen in the shell.
This image is from the 2MASS survey in the infra-red part of the electromagnetic spectrum.
Image credit: 2MASS