Astronomy:Micronova

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Short description: Explosive stellar phenomenon about one millionth the strength of a classical nova

File:Artist’s animation of a micronova.gif A micronova is a type of thermonuclear explosion on the surface of a white dwarf much smaller than the strength of a nova; being about 1×1039 ergs (1.0×10−12 foe; 1.0×1032 J) in strength, about a millionth that of a typical nova. The phenomenon was first described in April 2022.[1][2][3]

History

A team led by Durham University researchers announced on 20 April 2022 that they identified three micronovae using data from the Transiting Exoplanet Survey Satellite (TESS).[4] The team discovered with TESS that two of the micronovae occurred on white dwarfs, with the astronomers confirming with the Very Large Telescope that the third occurred on a white dwarf as well.[5]

The phenomenon had previously been observed in the white dwarf binary TV Columbae using data from the International Ultraviolet Explorer.[6] However the data was not sufficient to infer the physical mechanism behind the explosion.

Formation

Micronovae specifically form on white dwarfs that have strong magnetic fields, as fields send material toward the star's magnetic poles. This causes the hydrogen fusion explosions on the surface to be more localized and small than a typical nova.[5]

References

  1. ↑ S. Scaringi; P.J. Groot; C.Knigge; J.-P. Lasota; D. de Martino; Y. Cavecchi; D.A.H. Buckley; M.E. Camisassa (2022-04-19). "Triggering micronovae through magnetically confined accretion flows in accreting white dwarfs". Monthly Notices of the Royal Astronomical Society: Letters 514: L11–L15. doi:10.1093/mnrasl/slac042. 
  2. ↑ S. Scaringi; P. J. Groot; C. Knigge; A. J. Bird; E. Breedt; D. A. H. Buckley; Y. Cavecchi; N. D. Degenaar et al. (2022-04-20). "Localized thermonuclear bursts from accreting magnetic white dwarfs". Nature 604 (7906): 447–450. doi:10.1038/s41586-022-04495-6. ISSN 1476-4687. PMID 35444319. Bibcode: 2022Natur.604..447S. https://doi.org/10.1038/s41586-022-04495-6. 
  3. ↑ Ouellette, Jennifer (20 April 2022). "Meet the micronova: Astronomers discovered new type of stellar explosion". Ars Technica. https://arstechnica.com/science/2022/04/meet-the-micronova-astronomers-discovered-new-type-of-stellar-explosion/. 
  4. ↑ Kizer Whitt, Kelly (25 April 2022). "Micronovas are new! They're small, but mighty". EarthSky. https://earthsky.org/space/micronovas-small-mighty-like-nova-explosions/. 
  5. ↑ 5.0 5.1 Strickland, Ashley (2022-04-20). "Small 'micronova' explosion burns through tons of material within hours" (in en). https://www.cnn.com/2022/04/20/world/micronova-star-explosion-discovery-scn/index.html. 
  6. ↑ Szkody, P.; Mateo, M. (1984). "An unprecedented UV/optical flare in TV Columbae" (in en). The Astrophysical Journal 280: 729. doi:10.1086/162045. ISSN 0004-637X. Bibcode: 1984ApJ...280..729S. 

See also




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