One of the study's authors Professor Robert Fesen of Dartmouth College in New Hampshire says,"This is the first time we've actually seen such a complete image of what the interior of this thing looks like,"
Cassiopeia A was created 340 years ago when a massive star exploded to form a neutron star.In this type of explosion, known as a core-collapse supernova, the outer layers of the star drop in free fall, reaching speeds of 70,000 kilometres per second, a significant fraction of the speed of light. But, somehow that material suddenly stops and ends up travelling the other way at up to 10,000 kilometres per second.
Scientists call this sudden reversal a "bounce", but until now they've been unsure exactly how it happens.
This study was published in the journal Science.
Source:- ABC Science.