It wasn’t anything interesting until it happened but the star V838 Monoceroti, which had simply sat in obscurity, flared up in 2002 to become 600,000 more luminous than our own Sun. It didn’t take long for the star to fade back into the darkness but the Hubble Space Telescope managed to get quite a few pictures of it during its active phase. (Click for animated version)
In this series of images you can see how the star’s outer layers were first expelled and then cut away by the powerful radiation from the star. The event was made even more interesting by the fact that a ‘light echo‘ was seen. During the expansion the object appeared to expand faster than the speed of light – the effect was however merely an astronomical optical illusion.