A failed supernova is an

astronomical event Astronomical events are celestial body events such as eclipses, novae or planetary collisions studied by the scientific discipline of astronomy, whereas "astronomy events" refers to social events such as academic meetings, conferences and othe ...

in time domain astronomy in which a star suddenly brightens as in the early stage of a

supernova A supernova (: supernovae or supernovas) is a powerful and luminous explosion of a star. A supernova occurs during the last stellar evolution, evolutionary stages of a massive star, or when a white dwarf is triggered into runaway nuclear fusion ...

, but then does not increase to the massive flux of a supernova. They could be counted as a subcategory of

supernova imposter Supernova impostors are stellar explosions that appear at first to be a supernova but do not destroy their progenitor stars. As such, they are a class of extra-powerful novae. They are also known as Type V supernovae, Eta Carinae analogs, and g ...

s. They have sometimes misleadingly been called unnovae.

Overview

Failed supernovae are thought to create

stellar black hole A stellar black hole (or stellar-mass black hole) is a black hole formed by the gravitational collapse of a star. They have masses ranging from about 5 to several tens of solar masses. They are the remnants of supernova explosions, which may be ...

s by the collapsing of a

red supergiant Red supergiants (RSGs) are stars with a supergiant luminosity class ( Yerkes class I) and a stellar classification K or M. They are the largest stars in the universe in terms of volume, although they are not the most massive or luminous. Betelg ...

star in the early stages of a supernova. When the star can no longer support itself, the core collapses completely, forming a

stellar-mass black hole A stellar black hole (or stellar-mass black hole) is a black hole formed by the gravitational collapse of a star. They have masses ranging from about 5 to several tens of solar masses. They are the remnants of supernova explosions, which may be ...

, 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 involve

supergiant star Supergiants are among the most massive and most luminous stars. Supergiant stars occupy the top region of the Hertzsprung–Russell diagram, with absolute magnitude, absolute visual magnitudes between about −3 and −8. The temperatures of supe ...

s with masses above 17

solar masses The solar mass () is a frequently used unit of mass in astronomy, equal to approximately . It is approximately equal to the mass of the Sun. It is often used to indicate the masses of other stars, as well as stellar clusters, nebulae, galaxies ...

. Failed supernovae are one of several events that theoretically signal the advent of a

black hole A black hole is a massive, compact astronomical object so dense that its gravity prevents anything from escaping, even light. Albert Einstein's theory of general relativity predicts that a sufficiently compact mass will form a black hole. Th ...

born from an extremely massive star, others including

hypernova A hypernova is a very energetic supernova which is believed 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 astrophysical jets and surrounded b ...

e and long-duration

gamma-ray burst In gamma-ray astronomy, gamma-ray bursts (GRBs) are extremely energetic events occurring in distant Galaxy, galaxies which represent the brightest and most powerful class of explosion in the universe. These extreme Electromagnetic radiation, ele ...

Structure and process

Theoretically, a

star may be too massive to explode into a

, and collapse directly into being a

, without the bright flash. They would however generate a burst of

gravitational wave Gravitational waves are oscillations of the gravitational field that Wave propagation, travel through space at the speed of light; they are generated by the relative motion of gravity, gravitating masses. They were proposed by Oliver Heaviside i ...

s. This process would occur in the higher mass red supergiants, explaining the absence of observed supernovae with such

progenitors In genealogy, a progenitor (rarer: primogenitor; or ''Ahnherr'') is the founder (sometimes one that is legendary) of a family, line of descent, gens, clan, tribe, noble house, or ethnic group.. Ebenda''Ahnherr:''"Stammvater eines Geschlech ...

List of failed supernovae candidates

References

External links

{{Supernovae + Astronomical events