A nova and supernova are both bright events in the sky that are generally visible during the night to the naked eye. Until very recently, they were used very interchangeably. However, recent discoveries have found that the two have completely different causes.
Origin
Tyco Brahe coined the term “nova” after observing the supernova SN 1572 in the constellation Cassiopeia in the 16th century. He described it in his book De Stella nova, which is Latin for “concerning the new star”. It was from here that the term nova was coined, though strictly speaking, the observed event was a supernova.
Cataclysmic nuclear explosion
Innova is a cataclysmic nuclear explosion on a white dwarf. A nova is caused by the accretion of hydrogen onto the surface of the star. Due to the closeness, hydrogen accumulates on the surface of a white dwarf in a binary system, after being bled off from the larger star. It then ignites and starts nuclear fusion in a raging manner.
Mechanism
The gases are compacted on the white dwarf’s surface by its intense gravity, compressed and heated to very high temperatures as additional material is drawn in. As the white dwarf is dying and composed of degenerate matter, it does not absorb the material and inflate – as another star like the Sun would.
For most binary system parameters, the hydrogen-burning is thermally unstable once it has reached the required fusion temperatures. As a result, it rapidly converts a large amount of hydrogen into other heavier elements in a runaway reaction. This liberates an enormous amount of energy, blowing the remaining gases away from the white dwarf’s surface and producing an extremely bright outburst of light.
- compiled by Madhurani Chavan