A micronova is a putative 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
editA 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
editMicronovae 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 smaller than a typical nova.[5]
An alternative explanation for the phenomenon is that these represent magnetic reconnection events either in the accretion disks or in the coronae of the companion stars. The system V2487 Oph is one of the candidate micronovae, and has also shown standard recurrent novae. The properties of its short duration flares also do not agree with predictions for nuclear fusion events.[7]
References
edit- ^ S. Scaringi; P.J. Groot; C.Knigge; J.-P. Lasota; D. de Martino; Y. Cavecchi; D.A.H. Buckley; M.E. Camisassa (19 April 2022). "Triggering micronovae through magnetically confined accretion flows in accreting white dwarfs". Monthly Notices of the Royal Astronomical Society: Letters. 514: L11–L15. arXiv:2204.09073. doi:10.1093/mnrasl/slac042.
- ^ S. Scaringi; P. J. Groot; C. Knigge; A. J. Bird; E. Breedt; D. A. H. Buckley; Y. Cavecchi; N. D. Degenaar; D. de Martino; C. Done; M. Fratta; K. Iłkiewicz; E. Koerding; J.-P. Lasota; C. Littlefield; C. F. Manara; M. O’Brien; P. Szkody; F. X. Timmes (20 April 2022). "Localized thermonuclear bursts from accreting magnetic white dwarfs". Nature. 604 (7906): 447–450. arXiv:2204.09070. Bibcode:2022Natur.604..447S. doi:10.1038/s41586-022-04495-6. ISSN 1476-4687. PMID 35444319. S2CID 248266728.
- ^ Ouellette, Jennifer (20 April 2022). "Meet the micronova: Astronomers discovered new type of stellar explosion". Ars Technica.
- ^ Kizer Whitt, Kelly (25 April 2022). "Micronovas are new! They're small, but mighty". EarthSky.
- ^ a b Strickland, Ashley (20 April 2022). "Small 'micronova' explosion burns through tons of material within hours". CNN. Retrieved 14 March 2023.
- ^ Szkody, P.; Mateo, M. (1984). "An unprecedented UV/optical flare in TV Columbae". The Astrophysical Journal. 280: 729. Bibcode:1984ApJ...280..729S. doi:10.1086/162045. ISSN 0004-637X.
- ^ Schaefer, Bradley E.; Pagnotta, Ashley; Zoppelt, Seth (2 March 2022). "Discovery of extreme, roughly daily superflares on the recurrent nova V2487 Oph". Monthly Notices of the Royal Astronomical Society. 512 (2). Oxford University Press: 1924–1943. arXiv:2201.04080. doi:10.1093/mnras/stac443. eISSN 1365-2966. ISSN 0035-8711 – via Royal Astronomical Society.
See also
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The dictionary definition of micronova at Wiktionary
