Astronomy:Failed supernova

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A failed supernova is an astronomical event in time domain astronomy in which a star suddenly brightens as in the early stage of a supernova, but then does not increase to the massive flux of a supernova. They could be counted as a subcategory of supernova imposters. They have sometimes misleadingly been called unnovae.[1]

Overview

Failed supernovae are thought to create stellar black holes by the collapsing of a red supergiant 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, 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 stars with masses above 17 solar masses.

Failed supernovae are one of several events that theoretically signal the advent of a black hole born from an extremely massive star, others including hypernovae and long-duration gamma-ray bursts.

Structure and process

Theoretically, a red supergiant star may be too massive to explode into a supernova, and collapse directly into being a black hole, without the bright flash. They would however generate a burst of gravitational waves. This process would occur in the higher mass red supergiants, explaining the absence of observed supernovae with such progenitors.[2][3][4]

List of failed supernovae candidates

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]

References

  1. Woosley, S. E.; Heger, Alexander (2012). "Long Gamma-Ray Transients from Collapsars". The Astrophysical Journal 752: 32. doi:10.1088/0004-637X/752/1/32. Bibcode2012ApJ...752...32W. 
  2. 2.0 2.1 2.2 Lee Billings (November 2015). "Gone Without A Bang". Scientific American 313 (5): 26–27. doi:10.1038/scientificamerican1115-26b. PMID 26638393. Bibcode2015SciAm.313e..26B. 
  3. Jon Voisey (2 April 2011). "Finding the Failed Supernovae". Universe Today. http://www.universetoday.com/84596/finding-the-failed-supernovae/. 
  4. 4.0 4.1 Eugene Myers (27 September 2016). "This star was so massive it ate itself before it could go supernova". Astronomy Magazine. http://www.astronomy.com/news/2016/09/this-star-was-so-massive-it-ate-itself-before-it-could-go-supernova. 
  5. Reynolds, Thomas M.; Fraser, Morgan; Gilmore, Gerard (21 July 2015). "Gone without a bang: An archival HST survey for disappearing massive stars". Monthly Notices of the Royal Astronomical Society 453 (3): 2885–2900. November 2015. doi:10.1093/mnras/stv1809. Bibcode2015MNRAS.453.2885R. 
  6. Gerke, J. R.; Kochanek, C. S.; Stanek, K. Z. (6 November 2014). "The Search for Failed Supernovae with The Large Binocular Telescope: First Candidates". Monthly Notices of the Royal Astronomical Society 450 (3): 3289–3305. July 2015. doi:10.1093/mnras/stv776. Bibcode2015MNRAS.450.3289G. 

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