The most famous supernova ever, 1987A, is celebrating its 25th anniversary this year.
The link below shows the brightening of material (knots) in the ring surrounding the remnant over time.
This occurs as an outward-moving blast wave collides with the ring material and shock-heats it.
See the time-lapse by clicking on the image at http://apod.nasa.gov/apod/ap120227.html
Animation: http://www.youtube.com/watch?v=QfiwDXv6g0Q
Article: http://www.astronomynow.com/news/n1202/23sn/
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