What is an Hypernova ?

 A hypernova (sometimes called a Collapsar) is a very energetic supernova thought to result from an extreme core-collapse scenario. In this case, a massive star (>30 solar masses) collapses to form a rotating black hole emitting twin energetic jets and surrounded by an accretion disk. It is a type of stellar explosion that ejects material with an unusually high kinetic energy,an order of magnitude higher than most supernovae, with a luminosity at least 10 times greater. Hypernovae are one of the mechanisms for producing long gamma ray bursts , which range from 2 seconds to over a minute in duration. They have also been referred to as superluminous supernovae, though that classification also includes other types of extremely luminous stellar explosions that have different origins.

Hypernovae are now widely accepted to be supernovae with ejecta having a kinetic energy larger than about 10⁴⁵ joule, an order of magnitude higher than a typical core collapse supernova.

The ejected nickel masses are large and the ejection velocity up to 99% of the speed of light.

Unusually bright radio supernovae have been observed as counterparts to hypernovae, and have been termed "radio hypernovae".