What is meant by supernova?

Question

What is meant by supernova?

Answer 1

the explosion of a star, possibly caused by gravitational collapse, during which the star's luminosity increases by as much as 20 magnitudes and most of the star's mass is blown away at very high velocity, sometimes leaving behind an extremely dense core.  

Answer 2

A supernova is a catastropihc stellar explosion.

Basically the star collpases inwards and then explodes outwards throwing material back into space.

During this time - the "star" i.e. the explosion is as bright as a whole galaxy (about a billion times as bright as the sun), so we can detect them at large distances.

There are two types of supernovae - ones that come from massive stars (>10times the mass of the sun; called Type II) and ones that come from binary stars (called type I).

In both cases the explosion occurs because of runaway nucelar fusion eating up all the fuel, and then the star has to collapse in on itself. It does this so fast that collisions between particles cause it to rebound outwards and explode.

(ps - apologies for editing late - Y!A kept telling me it was on a breather when I was trying to submit my answer - ho hum)

Answer 3

A supernova is the name given to an exploding star, which dramatically increases in brightness. The name comes from the word "nova", meaning "new".

At first, stars that suddenly appeared due to an increase in brightness were called "stella nova", or "new star". These are now classified according to the increase in luminosity. A nova increases in brightness a certain amount of times, a supernova increases at least 100 times more than a nova, and a hypernova is the most devastating explosion so far discovered.

Supernovae can leave remnants, but the original star is destroyed due to the explosive force. Novae, however, can remain almost intact, as these energy releases are not as fierce.

Answer 4

It is a stellar explosion, where a lot of energy is released.

Energy that would take years for the sun to produce.

Answer 5

Simply put, it's a steller explosion with vasts amounts of radiation emitted.

Answer 6

When a very large star, more than one hundred times the mass of our sun, runs out of fuel, the radiation preassure that held its gravity at bay, suddenly vanishes, the result is a sudden collapse of the star's gasses, it can collapes in less than one second, so much enegy is generated the stars brighness increases by a factor of billions. A rebound effect takes place, the outer layers of the star are blown into space at the same time as elements heavier than iron are created, the event can be so violent that most the star's galaxy can be destroyed, fortunately this is a rare event. What is left is usually a neutron star, more rarely a black hole may result.  

Answer 7

http://www.google.com/search?q=define%3A...

Answer 8

A supernova is a type of exploding star. They occur every 50 years or so in the milky way and are thus considered relatively rare.

They appear as very bright stars. I do remember a whole lot of other things about them, but my brain appears not to be working.

You should read Bill Bryson's 'A Short History of Nearly Everything' because there's a good bit in there about supernovae.