Space & Innovation

Why Do Stars Explode?

What happens when stars die? You might find yourself a bit "starstruck" at just how huge their exit can be.

In the realm of science, it's generally acknowledged that astrophysicists have all the best technical terms: Quasar. Parsec. Blueshift. Event horizon.

Then there's the supernova, a genuinely spectacular word that describes a genuinely spectacular event. In this edition of DNews, intrepid explorer Julian Huguet determines what separates a supernova from a regular old nova.

Supernovae -- the plural form is even better -- occur when stars of a sufficient magnitude exhaust their supply of hydrogen fuel and decide to go out with the mother of all bangs. In fact, a supernova explosion is the single most powerful force ever encountered in the known universe, emitting the radiant energy of an entire galaxy in one flash of glory.

Fortunately for the cosmos, not all stars end their evolutionary journey as supernovae. Our own Sun, for instance, will perform a much more modest flash and fade in about five billion years and retire as a white dwarf. Supernovae are quite rare, actually, at least in our celestial neighborhood. Of the billions of stars in the Milky Way, only two or three go supernova each century.

RELATED: Astronomers See Supernova Shockwave for First Time

So what determines whether a star will go out as a supernova? That would be the Chandrasekhar limit, named for Indian physicist Subrahmanyan Chandrasekhar. The term refers to a particular stellar mass limit -- roughly 1.44 times the size of our Sun -- that serves as a kind of dividing line. Stars below this threshold retire peacefully. Stars above the threshold collapse under the force of their own gravity, setting off a titanic chain reaction.

The resulting detonation fuses together the usual light elements -- helium, carbon, oxygen -- and creates all those heavy elements on the periodic table. It also distributes said elements around the universe, making possible life as we know it.

Check out the video for more details, plus some startling images and surprising numbers on recently recorded supernovae.

-- Glenn McDonald

Learn More:

Scientific American: Found: The Most Powerful Supernova Ever Seen

Space Telescope: Missing Link Found Between Supernovae And Black Holes

NASA: Veil Nebula Supernova Remnant