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Flare star

December 10, 2023

A flare star is a variable star that can undergo unpredictable dramatic increases in brightness for a few minutes. It is believed that the flares on flare stars are analogous to solar flares in that they are due to the magnetic energy stored in the stars' atmospheres. The brightness increase is across the spectrum, from X-rays to radio waves. Flare activity among late-type stars was first reported by A. van Maanen in 1945, for WX UMa and YZ CMi.[1] However, the best-known flare star is UV Ceti, first observed to flare in 1948. Today similar flare stars are classified as UV Ceti type variable stars (using the abbreviation UV) in variable star catalogs such as the General Catalogue of Variable Stars.

Most flare stars are dim red dwarfs, although recent research indicates that less massive brown dwarfs might also be capable of flaring.[citation needed] The more massive RS Canum Venaticorum variables (RS CVn) are also known to flare, but it is understood that these flares are induced by a companion star in a binary system which causes the magnetic field to become tangled. Additionally, nine stars similar to the Sun had also been seen to undergo flare events[2] prior to the flood of superflare data from the Kepler observatory. It has been proposed that the mechanism for this is similar to that of the RS CVn variables in that the flares are being induced by a companion, namely an unseen Jupiter-like planet in a close orbit.[3]

Nearby flare stars edit

Flare stars are intrinsically faint, but have been found to distances of 1,000 light years from Earth.[4] On April 23, 2014, NASA's Swift satellite detected the strongest, hottest, and longest-lasting sequence of stellar flares ever seen from a nearby red dwarf, DG Canum Venaticorum. The initial blast from this record-setting series of explosions was as much as 10,000 times more powerful than the largest solar flare ever recorded.[5]

Proxima Centauri edit

The Sun's nearest stellar neighbor Proxima Centauri is a flare star that undergoes occasional increases in brightness because of magnetic activity.[6] The star's magnetic field is created by convection throughout the stellar body, and the resulting flare activity generates a total X-ray emission similar to that produced by the Sun.[7]

Wolf 359 edit

The flare star Wolf 359 is another near neighbor (2.39 ± 0.01 parsecs). This star, also known as Gliese 406 and CN Leo, is a red dwarf of spectral class M6.5 that emits X-rays.[8] It is a UV Ceti flare star,[9] and has a relatively high flare rate.

The mean magnetic field has a strength of about 2.2 kG (0.2 T), but this varies significantly on time scales as short as six hours.[10] By comparison, the magnetic field of the Sun averages 1 G (100 μT), although it can rise as high as 3 kG (0.3 T) in active sunspot regions.[11]

Barnard's Star edit

Barnard's Star is the fourth nearest star to the Sun. Given its age, at 7–12 billion years of age, Barnard's Star is considerably older than the Sun. It was long assumed to be quiescent in terms of stellar activity. However, in 1998, astronomers observed an intense stellar flare, showing that Barnard's Star is a flare star.[12][13]

TVLM513-46546 edit

TVLM 513-46546 is a very low mass M9 flare star, at the boundary between red dwarfs and brown dwarfs. Data from Arecibo Observatory at radio wavelengths determined that the star flares every 7054 s with a precision of one one-hundredth of a second.[14]

2MASS JJ18352154-3123385 A edit

The more massive member of the binary star 2MASS J1835, an M6.5 star, has strong X-ray activity indicative of a flare star, although it has never been directly observed to flare.

Record-setting flares edit

The most powerful stellar flare detected, as of December 2005, may have come from the active binary II Peg.[15] Its observation by Swift suggested the presence of hard X-rays in the well-established Neupert effect as seen in solar flares.

See also edit

  • Solar flare – Eruption of electromagnetic radiation
  • Superflare – Strong explosion observed on stars
  • Variable star – Star whose brightness fluctuates, as seen from Earth

References edit

  1. ^ Joy, Alfred H. (February 1954). "Variable Stars of Low Luminosity". Publications of the Astronomical Society of the Pacific. 66 (388): 5. Bibcode:1954PASP...66....5J. doi:10.1086/126639.
  2. ^ Schaefer, Bradley E.; King, Jeremy R.; Deliyannis, Constantine P. (February 2000). "Superflares on Ordinary Solar-Type Stars". The Astrophysical Journal. 529 (2): 1026. arXiv:astro-ph/9909188. Bibcode:2000ApJ...529.1026S. doi:10.1086/308325. S2CID 10586370.
  3. ^ Rubenstein, Eric; Schaefer, Bradley E. (February 2000). "Are Superflares on Solar Analogues Caused by Extrasolar Planets?". The Astrophysical Journal. 529 (2): 1031. arXiv:astro-ph/9909187. Bibcode:2000ApJ...529.1031R. doi:10.1086/308326. S2CID 15709625.
  4. ^ Kulkarni, Shrinivas R.; Rau, Arne (2006). "The Nature of the Deep Lens Survey Fast Transients". Astrophysical Journal. 644 (1): L63. arXiv:astro-ph/0604343. Bibcode:2006ApJ...644L..63K. doi:10.1086/505423. S2CID 116948759.
  5. ^ NASA/Goddard Space Flight Center, "NASA's Swift mission observes mega flares from nearby red dwarf star", ScienceDaily, 30 September 2014
  6. ^ Christian, Damian J.; Mathioudakis, Michail; Bloomfield, D. Shaun; Dupuis, Jean; Keenan, Francis P. (2004). "A Detailed Study of Opacity in the Upper Atmosphere of Proxima Centauri". Astrophysical Journal. 612 (2): 1140–6. Bibcode:2004ApJ...612.1140C. doi:10.1086/422803. hdl:10211.3/172067.
  7. ^ Wood, Brian E.; Linsky, Jeffrey L.; Müller, Hans-Reinhard; Zank, Gary P. (2001). "Observational Estimates for the Mass-Loss Rates of α Centauri and Proxima Centauri Using Hubble Space Telescope Lyα Spectra". Astrophysical Journal. 547 (1): L49–L52. arXiv:astro-ph/0011153. Bibcode:2001ApJ...547L..49W. doi:10.1086/318888. S2CID 118537213.
  8. ^ Schmitt, Juergen H. M. M.; Fleming, Thomas A.; Giampapa, Mark S. (September 1995). "The X-Ray View of the Low-Mass Stars in the Solar Neighborhood". Astrophysical Journal. 450 (9): 392–400. Bibcode:1995ApJ...450..392S. doi:10.1086/176149.
  9. ^ Gershberg, Roald E.; Shakhovskaia, Nadezhda I. (1983). "Characteristics of activity energetics of the UV Cet-type flare stars". Astrophysics and Space Science. 95 (2): 235–53. Bibcode:1983Ap&SS..95..235G. doi:10.1007/BF00653631. S2CID 122101052.
  10. ^ Reiners, Ansgar; et al. (2007). "Rapid magnetic flux variability on the flare star CN Leonis" (PDF). Astronomy and Astrophysics. 466 (2): L13–L16. arXiv:astro-ph/0703172. Bibcode:2007A&A...466L..13R. doi:10.1051/0004-6361:20077095. S2CID 17926213.
  11. ^ . National Optical Astronomy Observatory. 7 January 2007. Archived from the original on 2019-06-22. Retrieved 2006-05-24.
  12. ^ Croswell, Ken (November 2005). "A Flare for Barnard's Star". Astronomy Magazine. Kalmbach Publishing Co. Retrieved 2006-08-10.
  13. ^ "V2500 Oph". The International Variable Star Index. Retrieved 18 November 2015.
  14. ^ Wolszczan, A.; Route, M. (2014). "Timing Analysis of the Periodic Radio and Optical Brightness Variations of the Ultracool Dwarf, TVLM 513-46546". The Astrophysical Journal. 788 (1): 23. arXiv:1404.4682. Bibcode:2014ApJ...788...23W. doi:10.1088/0004-637X/788/1/23. S2CID 119114679.
  15. ^ Osten, Rachel; Drake, Steve; Tueller, Jack; Cameron, Brian; "Swift Observations of Stellar Flares", Swift Team Meeting, 1 May 2007

External links edit

  • UV Ceti and the flare stars, Autumn 2003 Variable Star Of The Season prepared by Matthew Templeton, AAVSO (www.aavso.org)
  • Stellar Flares - D. Montes, UCM.

December 10, 2023
flare, star, flare, star, variable, star, that, undergo, unpredictable, dramatic, increases, brightness, minutes, believed, that, flares, flare, stars, analogous, solar, flares, that, they, magnetic, energy, stored, stars, atmospheres, brightness, increase, ac. A flare star is a variable star that can undergo unpredictable dramatic increases in brightness for a few minutes It is believed that the flares on flare stars are analogous to solar flares in that they are due to the magnetic energy stored in the stars atmospheres The brightness increase is across the spectrum from X rays to radio waves Flare activity among late type stars was first reported by A van Maanen in 1945 for WX UMa and YZ CMi 1 However the best known flare star is UV Ceti first observed to flare in 1948 Today similar flare stars are classified as UV Ceti type variable stars using the abbreviation UV in variable star catalogs such as the General Catalogue of Variable Stars Most flare stars are dim red dwarfs although recent research indicates that less massive brown dwarfs might also be capable of flaring citation needed The more massive RS Canum Venaticorum variables RS CVn are also known to flare but it is understood that these flares are induced by a companion star in a binary system which causes the magnetic field to become tangled Additionally nine stars similar to the Sun had also been seen to undergo flare events 2 prior to the flood of superflare data from the Kepler observatory It has been proposed that the mechanism for this is similar to that of the RS CVn variables in that the flares are being induced by a companion namely an unseen Jupiter like planet in a close orbit 3 Contents 1 Nearby flare stars 1 1 Proxima Centauri 1 2 Wolf 359 1 3 Barnard s Star 1 4 TVLM513 46546 1 5 2MASS JJ18352154 3123385 A 2 Record setting flares 3 See also 4 References 5 External linksNearby flare stars editFlare stars are intrinsically faint but have been found to distances of 1 000 light years from Earth 4 On April 23 2014 NASA s Swift satellite detected the strongest hottest and longest lasting sequence of stellar flares ever seen from a nearby red dwarf DG Canum Venaticorum The initial blast from this record setting series of explosions was as much as 10 000 times more powerful than the largest solar flare ever recorded 5 Proxima Centauri edit The Sun s nearest stellar neighbor Proxima Centauri is a flare star that undergoes occasional increases in brightness because of magnetic activity 6 The star s magnetic field is created by convection throughout the stellar body and the resulting flare activity generates a total X ray emission similar to that produced by the Sun 7 Wolf 359 edit The flare star Wolf 359 is another near neighbor 2 39 0 01 parsecs This star also known as Gliese 406 and CN Leo is a red dwarf of spectral class M6 5 that emits X rays 8 It is a UV Ceti flare star 9 and has a relatively high flare rate The mean magnetic field has a strength of about 2 2 kG 0 2 T but this varies significantly on time scales as short as six hours 10 By comparison the magnetic field of the Sun averages 1 G 100 mT although it can rise as high as 3 kG 0 3 T in active sunspot regions 11 Barnard s Star edit Barnard s Star is the fourth nearest star to the Sun Given its age at 7 12 billion years of age Barnard s Star is considerably older than the Sun It was long assumed to be quiescent in terms of stellar activity However in 1998 astronomers observed an intense stellar flare showing that Barnard s Star is a flare star 12 13 TVLM513 46546 edit TVLM 513 46546 is a very low mass M9 flare star at the boundary between red dwarfs and brown dwarfs Data from Arecibo Observatory at radio wavelengths determined that the star flares every 7054 s with a precision of one one hundredth of a second 14 2MASS JJ18352154 3123385 A edit The more massive member of the binary star 2MASS J1835 an M6 5 star has strong X ray activity indicative of a flare star although it has never been directly observed to flare Record setting flares editThe most powerful stellar flare detected as of December 2005 may have come from the active binary II Peg 15 Its observation by Swift suggested the presence of hard X rays in the well established Neupert effect as seen in solar flares See also editSolar flare Eruption of electromagnetic radiation Superflare Strong explosion observed on stars Variable star Star whose brightness fluctuates as seen from EarthReferences edit Joy Alfred H February 1954 Variable Stars of Low Luminosity Publications of the Astronomical Society of the Pacific 66 388 5 Bibcode 1954PASP 66 5J doi 10 1086 126639 Schaefer Bradley E King Jeremy R Deliyannis Constantine P February 2000 Superflares on Ordinary Solar Type Stars The Astrophysical Journal 529 2 1026 arXiv astro ph 9909188 Bibcode 2000ApJ 529 1026S doi 10 1086 308325 S2CID 10586370 Rubenstein Eric Schaefer Bradley E February 2000 Are Superflares on Solar Analogues Caused by Extrasolar Planets The Astrophysical Journal 529 2 1031 arXiv astro ph 9909187 Bibcode 2000ApJ 529 1031R doi 10 1086 308326 S2CID 15709625 Kulkarni Shrinivas R Rau Arne 2006 The Nature of the Deep Lens Survey Fast Transients Astrophysical Journal 644 1 L63 arXiv astro ph 0604343 Bibcode 2006ApJ 644L 63K doi 10 1086 505423 S2CID 116948759 NASA Goddard Space Flight Center NASA s Swift mission observes mega flares from nearby red dwarf star ScienceDaily 30 September 2014 Christian Damian J Mathioudakis Michail Bloomfield D Shaun Dupuis Jean Keenan Francis P 2004 A Detailed Study of Opacity in the Upper Atmosphere of Proxima Centauri Astrophysical Journal 612 2 1140 6 Bibcode 2004ApJ 612 1140C doi 10 1086 422803 hdl 10211 3 172067 Wood Brian E Linsky Jeffrey L Muller Hans Reinhard Zank Gary P 2001 Observational Estimates for the Mass Loss Rates of a Centauri and Proxima Centauri Using Hubble Space Telescope Lya Spectra Astrophysical Journal 547 1 L49 L52 arXiv astro ph 0011153 Bibcode 2001ApJ 547L 49W doi 10 1086 318888 S2CID 118537213 Schmitt Juergen H M M Fleming Thomas A Giampapa Mark S September 1995 The X Ray View of the Low Mass Stars in the Solar Neighborhood Astrophysical Journal 450 9 392 400 Bibcode 1995ApJ 450 392S doi 10 1086 176149 Gershberg Roald E Shakhovskaia Nadezhda I 1983 Characteristics of activity energetics of the UV Cet type flare stars Astrophysics and Space Science 95 2 235 53 Bibcode 1983Ap amp SS 95 235G doi 10 1007 BF00653631 S2CID 122101052 Reiners Ansgar et al 2007 Rapid magnetic flux variability on the flare star CN Leonis PDF Astronomy and Astrophysics 466 2 L13 L16 arXiv astro ph 0703172 Bibcode 2007A amp A 466L 13R doi 10 1051 0004 6361 20077095 S2CID 17926213 Calling Dr Frankenstein Interactive Binaries Show Signs of Induced Hyperactivity National Optical Astronomy Observatory 7 January 2007 Archived from the original on 2019 06 22 Retrieved 2006 05 24 Croswell Ken November 2005 A Flare for Barnard s Star Astronomy Magazine Kalmbach Publishing Co Retrieved 2006 08 10 V2500 Oph The International Variable Star Index Retrieved 18 November 2015 Wolszczan A Route M 2014 Timing Analysis of the Periodic Radio and Optical Brightness Variations of the Ultracool Dwarf TVLM 513 46546 The Astrophysical Journal 788 1 23 arXiv 1404 4682 Bibcode 2014ApJ 788 23W doi 10 1088 0004 637X 788 1 23 S2CID 119114679 Osten Rachel Drake Steve Tueller Jack Cameron Brian Swift Observations of Stellar Flares Swift Team Meeting 1 May 2007External links editUV Ceti and the flare stars Autumn 2003 Variable Star Of The Season prepared by Matthew Templeton AAVSO www aavso org Stellar Flares D Montes UCM Retrieved from https en wikipedia org w index php title Flare star amp oldid 1180265977, wikipedia, wiki, book, books, library,

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