Watch video as a star blows up

When you look up at the stars a lot, there isn't a lot that seems to change. The planets change position. The moon varies between getting out of the way and totally trashing your night vision. And meteors...

But it isn't very often that - given the sheer enormity of cosmic time scales - we get to see something actually change before our eyes.

So the capture on film of a star actually going nova is a big deal.



The video clip notes explain:

Nova Sagittarii 2012 as seen from the US NRL's SECCHI HI-1 instrument on the NASA STEREO-B spacecraft. The movie runs from April 20 - 24, 2012, with approximately one frame per hour.

And UniverseToday describe how a nova occurs:

Unlike a supernova, which is the cataclysmic collapse and explosion of a massive star whose core has finally fused its last, a nova is the result of material falling onto the surface of a white dwarf that’s part of a binary pair. The material, typically hydrogen and helium gas, is drawn off the white dwarf’s partner which has expanded into a red giant.

Eventually the white dwarf cannot contain all of the material that it has sucked in from its neighbor… material which has been heated to tremendous temperatures on its surface as it got compressed further and further by the white dwarf’s incredibly strong gravity. Fusion occurs on the dwarf’s outermost layers, blasting its surface out into space in an explosion of light and energy.

This is a nova — so called because, when witnessed in the night sky, one could suddenly appear as a “new star” in the heavens — sometimes even outshining all other visible stars!

An individual nova will soon fade, but a white dwarf can produce many such flares over time. It all depends on how rapidly it’s accreting material (and how much there is available.)