Superluminous supernova
[verification needed] Hydrogen-rich SLSNe are classified as Type SLSN-II, with observed radiation passing through the changing opacity of a thick expanding hydrogen envelope.
Most hydrogen-poor events are classified as Type SLSN-I, with its visible radiation produced from a large expanding envelope of material powered by an unknown mechanism.
[6][verification needed] Increasing number of discoveries find that some SLSNe do not fit cleanly into these three classes, so further sub-classes or unique events have been described.
Many or all SLSN-I show spectra without hydrogen or helium but have lightcurves comparable to conventional type Ic supernovae, and are now classed as SLSN-Ic.
In recent years, much observational data on long-duration gamma-ray bursts have significantly increased our understanding of these events and made clear that the collapsar model produces explosions that differ only in detail from more or less ordinary supernovae and have energy ranges from approximately normal to around 100 times larger.
It is classified as a type Ic supernova due to its distinctive spectral properties in the radio spectrum, indicating the presence of relativistic matter.
Type IIn supernovae are all embedded in a dense nebula probably expelled from the progenitor star itself, and this circumstellar material (CSM) is thought to be the cause of the extra luminosity.
The theoretical basis for pair-instability collapse has been known for many decades[13] and was suggested as a dominant source of higher mass elements in the early universe as super-massive population III stars exploded.
In a pair-instability supernova, the pair production effect causes a sudden pressure drop in the star's core, leading to a rapid partial collapse.
[14] Models of the creation and subsequent spin-down of a magnetar yield much higher luminosities than regular supernova[15][16] events and match the observed properties[17][18] of at least some SLSNe.
There are still models for SLSN explosions produced from binary systems, white dwarf or neutron stars in unusual arrangements or undergoing mergers, and some of these are proposed to account for some observed gamma-ray bursts.
