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Afailed supernova is anastronomical event intime domain astronomy in which a star suddenly brightens as in the early stage of asupernova, but then does not increase to the massive flux of a supernova. They could be counted as a subcategory ofsupernova imposters. They have sometimes misleadingly been calledunnovae.[1][failed verification]
Failed supernovae are thought to createstellar black holes by the collapsing of ared supergiant star in the early stages of a supernova. When the star can no longer support itself, the core collapses completely, forming astellar-mass black hole, and consuming the nascent supernova without having the massive explosion. For a distant observer, the red supergiant star will seem to wink out of existence with little or no flare-up. The observed instances of these disappearances seem to involvesupergiant stars with masses above 17solar masses.
Failed supernovae are one of several events that theoretically signal the advent of ablack hole born from an extremely massive star, others includinghypernovae and long-durationgamma-ray bursts.
Theoretically, ared supergiant star may be too massive to explode into asupernova, and collapse directly into being ablack hole, without the bright flash. They would however generate a burst ofgravitational waves. This process would occur in the higher mass red supergiants, explaining the absence of observed supernovae with suchprogenitors.[2][3][4]
| Event | Date | Location | Notes | |
|---|---|---|---|---|
| NGC3021-CANDIDATE-1 | NGC 3021 09h 50m 55.39s +33° 33′ 14.5″ | Disappearance of a 25-30 MSun F8 supergiant observed in archival HST data | [2][5] | |
| N6946-BH1 | March 2009 | NGC 6946 20h 35m 27.56s +60° 08′ 08.2″ | Disappearance of an 18-25 MSun red supergiant | [2][6][4] |
