Difference between Nova and Supernova

As I said before a Nova is a completely different process compared with a Supernova. A Nova is actually a sudden brightness that spreads across the surface of a White dwarf--kind of a star. The brightness is the result of a fusion reaction that happens on the surface of the White dwarf, and that fusion reaction is initiated by the matter that was gravitated towards and got accumulated across the surface of the White dwarf from a nearby binary neighbor.

This doesn't cause any sort of huge impact on the White dwarf's dimensions or properties, and hence can happen again and again as long as its neighbor stays close enough, and the matter gets accumulated on its surface.

Supernova on the other hand is a complete destruction of a star that which can't able to withstand its own gravity, when it happens to reach a certain mass at the end of its fuel consumption. The limit being found as 1.4 solar masses by Chandrashekar and was popular as Chandrashekar Limit.

Obviously it happens just once for a star that supposedly reaches above or equals Chandrashekar Limit, after burning away its complete fuel, unlike Nova.

Supernova got classified in to two types depending up on the way it reaches the Chandrashekar Limit.

• The first one, as I mentioned earlier happens when a star can't burn anymore and endup above or across Chandrashekar Limit. This is more natural as it seems.

-- I will try to give a much detailed explanation in my next post. :)

• The second one happens for a White dwarf, where its resultant mass reaches the 'Limit' through accretion of mass from its nearby binary neighbor. It might look like Nova in the beginning but is more powerful and more devastating, as there will be no star left over--other than some Supernova Remnant--at the end of the process that lasts ranging from several weeks to months.
  

Earlier it was thought that the Supernova is a kind of bigger and brighter Nova and hence the name. And now, the name stayed but not the definition. A Supernova is in noway related to Nova where the former is caused by the gravitational collapse and the later by the fusion reaction.
The only thing that appears common for the both at times is White dwarf.
Read more...

What is a Supernova?

There was a star somewhere around the sky staying almost unnoticeable, and got burst out suddenly in to a blistering brightness; it's just a one more Supernova!--if not Nova.

The energy and light that was radiated in to the sky during the star's sudden outburst is so heavy that it can easily outshines the entire galaxy--for several weeks to several months depending on the star's mass-- where it resides in, and that happens every time. The energy that got released during the process equals the entire energy that our sun can generate in its entire lifetime.

The star explodes and expels the material it was hiding till then, in to the surrounding Interstellar medium at a velocity of up to 30,000 km/s(10% that of light's). The material thus got released expands taking the help of a Shock wave that was generated during the sudden explosion, in the form of gas and dust called a Supernova remnant.

Supernova happens very rare compared with Nova, which is a completely different process and happens very often. For a galaxy in the size of our Milky way, supernova happens just once in every 50 years. Anyways, it's a lot more common process and happens once in every sec, when we look through the entire universe(as the universe breeds stars every sec and they are not eternal).

It's not that every star that exists in the universe can eventually turn in to a Supernova, but is entirely depends on the mass of the star. A star that which reaches a mass that is greater than 1.4 times that of our sun's, at the end of it's fuel consumption, will explode in to a Supernova. And that 1.4 limit was found by Chandrashekar and hence named after him as Chandrashekar limit.

Our sun according to chandrashekar can't turn in to a supernova but will end up as a
White dwarf, when it gets completely devoured of its fuel. And even no possibility of forming a Nova or Supernova later on as there is no binary neighbor, close by.

There are two types of supernova and I will try to explain them in my next post. :)

Check this one too..

What is a Nova?
Read more...