For faster navigation, this Iframe is preloading the Wikiwand page for Solar flare.

Solar flare

An X5.4-class solar flare causing blooming, vertical streaking, and diffraction patterns to form in the image taken by the 131 Å (13.1 nm) sensor aboard the Solar Dynamics Observatory on 6 March 2012

A solar flare is a relatively intense, localized emission of electromagnetic radiation in the Sun's atmosphere. Flares occur in active regions and are often, but not always, accompanied by coronal mass ejections, solar particle events, and other eruptive solar phenomena. The occurrence of solar flares varies with the 11-year solar cycle.

Solar flares are thought to occur when stored magnetic energy in the Sun's atmosphere accelerates charged particles in the surrounding plasma. This results in the emission of electromagnetic radiation across the electromagnetic spectrum.

The extreme ultraviolet and x-ray radiation from solar flares is absorbed by the daylight side of Earth's upper atmosphere, in particular the ionosphere, and does not reach the surface. This absorption can temporarily increase the ionization of the ionosphere which may interfere with short-wave radio communication. The prediction of solar flares is an active area of research.

Flares also occur on other stars, where the term stellar flare applies.

Description

An X3.2-class solar flare observed in different wavelengths. Clockwise from top left: 304, 335, 131, and 193 Å

Solar flares are eruptions of electromagnetic radiation originating in the Sun's atmosphere.[1] They affect all layers of the solar atmosphere (photosphere, chromosphere, and corona).[2] The plasma medium is heated to >107 kelvin, while electrons, protons, and heavier ions are accelerated to near the speed of light.[3][4] Flares emit electromagnetic radiation across the electromagnetic spectrum, from radio waves to gamma rays.[2]

Flares occur in active regions, often around sunspots, where intense magnetic fields penetrate the photosphere to link the corona to the solar interior. Flares are powered by the sudden (timescales of minutes to tens of minutes) release of magnetic energy stored in the corona. The same energy releases may also produce coronal mass ejections (CMEs), although the relationship between CMEs and flares is not well understood.[5]

Associated with solar flares are flare sprays.[6] They involve faster ejections of material than eruptive prominences,[7] and reach velocities of 20 to 2000 kilometers per second.[8]

Frequency

The frequency of occurrence of solar flares varies with the 11-year solar cycle. It can typically range from several per day during solar maximum to less than one every week during solar minimum. Additionally, more powerful flares are less frequent than weaker ones. For example, X10-class (severe) flares occur on average about eight times per cycle, whereas M1-class (minor) flares occur on average about 2000 times per cycle.[9]

Erich Rieger discovered with coworkers in 1984, an approximately 154 day period in the occurrence of gamma-ray emitting solar flares at least since the solar cycle 19.[10] The period has since been confirmed in most heliophysics data and the interplanetary magnetic field and is commonly known as the Rieger period. The period's resonance harmonics also have been reported from most data types in the heliosphere.

The frequency distributions of various flare phenomena can be characterized by power-law distributions. For example, the peak fluxes of radio, extreme ultraviolet, and hard and soft X-ray emissions; total energies; and flare durations (see § Duration) have been found to follow power-law distributions.[11][12][13][14]: 23–28 

Duration

Observations of a solar flare by different instruments aboard the Solar Dynamics Observatory show varying durations.

The duration of a solar flare depends heavily on the wavelength of the electromagnetic radiation used in its calculation. This is due to different wavelengths being emitted through different processes and at different heights in the Sun's atmosphere.

A common measure of flare duration is the full width at half maximum (FWHM) time of soft X-ray flux within the wavelength bands 0.05 to 0.4 and 0.1 to 0.8 nanometres (0.5 to 4 and 1 to 8 ångströms) measured by the GOES spacecraft in geosynchronous orbit. The FWHM time spans from when a flare's flux first reaches halfway between its maximum flux and the background flux and when it again reaches this value as the flare decays. Using this measure, the duration of a flare ranges from approximately tens of seconds to several hours with a median duration of approximately 6 and 11 minutes in the 0.05 to 0.4 and 0.1 to 0.8 nanometre bands, respectively.[15][16]

Post-eruption loops and arcades

A post-eruption arcade present after an X5.7-class solar flare during the Bastille Day solar storm[17]

After the eruption of a solar flare, post-eruption loops made of hot plasma begin to form across the neutral line separating regions of opposite magnetic polarity near the flare's source. These loops extend from the photosphere up into the corona and form along the neutral line at increasingly greater distances from the source as time progresses.[18] The existence of these hot loops is thought to be continued by prolonged heating present after the eruption and during the flare's decay stage.[19]

In sufficiently powerful flares, typically of C-class or higher, the loops may combine to form an elongated arch-like structure known as a post-eruption arcade. These structures may last anywhere from multiple hours to multiple days after the initial flare.[18] In some cases, dark sunward-traveling plasma voids known as supra-arcade downflows may form above these arcades.[20]

Cause

Flares occur when accelerated charged particles, mainly electrons, interact with the plasma medium. Evidence suggests that the phenomenon of magnetic reconnection leads to this extreme acceleration of charged particles.[21] On the Sun, magnetic reconnection may happen on solar arcades – a type of prominence consisting of a series of closely occurring loops following magnetic lines of force.[22] These lines of force quickly reconnect into a lower arcade of loops leaving a helix of magnetic field unconnected to the rest of the arcade. The sudden release of energy in this reconnection is the origin of the particle acceleration. The unconnected magnetic helical field and the material that it contains may violently expand outwards forming a coronal mass ejection.[23] This also explains why solar flares typically erupt from active regions on the Sun where magnetic fields are much stronger.

Although there is a general agreement on the source of a flare's energy, the mechanisms involved are not well understood. It is not clear how the magnetic energy is transformed into the kinetic energy of the particles, nor is it known how some particles can be accelerated to the GeV range (109 electron volt) and beyond. There are also some inconsistencies regarding the total number of accelerated particles, which sometimes seems to be greater than the total number in the coronal loop.[24]

Classification

Soft X-ray

An M5.8, M2.3, and X2.8 flare were recorded by GOES-16 on 14 December 2023. Their corresponding peak fluxes in the 0.1 to 0.8 nm channel were 5.8×10−5, 2.3×10−5, and 2.8×10−4 W/m2, respectively.

The modern classification system for solar flares uses the letters A, B, C, M, or X, according to the peak flux in watts per square metre (W/m2) of soft X-rays with wavelengths 0.1 to 0.8 nanometres (1 to 8 ångströms), as measured by GOES satellites in geosynchronous orbit.

Classification Peak flux range (W/m2)
A < 10−7
B 10−7 – 10−6
C 10−6 – 10−5
M 10−5 – 10−4
X > 10−4

The strength of an event within a class is noted by a numerical suffix ranging from 1 up to, but excluding, 10, which is also the factor for that event within the class. Hence, an X2 flare is twice the strength of an X1 flare, an X3 flare is three times as powerful as an X1. M-class flares are a tenth the size of X-class flares with the same numeric suffix.[25] An X2 is four times more powerful than an M5 flare.[26] X-class flares with a peak flux that exceeds 10−3 W/m2 may be noted with a numerical suffix equal to or greater than 10.

This system was originally devised in 1970 and included only the letters C, M, and X. These letters were chosen to avoid confusion with other optical classification systems. The A and B classes were added in the 1990s as instruments became more sensitive to weaker flares. Around the same time, the backronym moderate for M-class flares and extreme for X-class flares began to be used.[27]

Importance

An earlier classification system, sometimes referred to as the flare importance, was based on H-alpha spectral observations. The scheme uses both the intensity and emitting surface. The classification in intensity is qualitative, referring to the flares as: faint (f), normal (n), or brilliant (b). The emitting surface is measured in terms of millionths of the hemisphere and is described below. (The total hemisphere area AH = 15.5 × 1012 km2.)

Classification Corrected area
(millionths of hemisphere)
S < 100
1 100–250
2 250–600
3 600–1200
4 > 1200

A flare is then classified taking S or a number that represents its size and a letter that represents its peak intensity, v.g.: Sn is a normal sunflare.[28]

Duration

Solar flares can also be classified based on their duration as either impulsive or long duration events (LDE). The time threshold separating the two is not well defined. The SWPC regards events requiring 30 minutes or more to decay to half maximum as LDEs, whereas Belgium's Solar-Terrestrial Centre of Excellence regards events with duration greater than 60 minutes as LDEs.[29][30]

Effects

Terrestrial

X-rays and extreme ultraviolet radiation emitted by solar flares are absorbed by the daylight side of Earth's atmosphere and do not reach the Earth's surface. Therefore, solar flares pose no direct danger to life on Earth. However, this absorption of high-energy electromagnetic radiation can temporarily increase the ionization of the upper atmosphere, which can interfere with short-wave radio communication, and can temporarily heat and expand the Earth's outer atmosphere. This expansion can increase drag on satellites in low Earth orbit, which can lead to orbital decay over time.[31]

Radio blackouts

The temporary increase in ionization of the daylight side of Earth's atmosphere, in particular the D layer of the ionosphere, can interfere with short-wave radio communications that rely on its level of ionization for skywave propagation. Skywave, or skip, refers to the propagation of radio waves reflected or refracted off of the ionized ionosphere. When ionization is higher than normal, radio waves get degraded or completely absorbed by losing energy from the more frequent collisions with free electrons.[1]

The level of ionization of the atmosphere correlates with the strength of the associated solar flare in soft X-ray radiation. The U.S. NOAA classifies radio blackouts by the peak soft X-ray intensity of the associated flare.

Classification Associated solar flare Description[9]
R1 M1 Minor radio blackout
R2 M5 Moderate radio blackout
R3 X1 Strong radio blackout
R4 X10 Severe radio blackout
R5 X20 Extreme radio blackout

Magnetic crochet

The increased ionization of the D and E layers of the ionosphere caused by large solar flares increases the electrical conductivity of these layers allowing for the flow of electric currents. These ionospheric currents induce a magnetic field which can be measured by ground-based magnetometers. This phenomenon is known as a magnetic crochet or solar flare effect (SFE).[32] These disturbances are on the order of a few nanoteslas, which is relatively minor compared to those induced by geomagnetic storms.[33]

In space

For astronauts in low earth orbit an expected radiation dose from the electromagnetic radiation emitted during a solar flare is about 0.05 gray, which is not immediately lethal on its own. Of much more concern for astronauts is the particle radiation associated with solar particle events.[34][better source needed]

Observations

Flares produce radiation across the electromagnetic spectrum, although with different intensity. They are not very intense in visible light, but they can be very bright at particular spectral lines. They normally produce bremsstrahlung in X-rays and synchrotron radiation in radio.[35]

History

Optical observations

Richard Carrington's sketch of the first recorded solar flare (A and B mark the initial bright points which moved over the course of five minutes to C and D before disappearing)[36]

Solar flares were first observed by Richard Carrington and Richard Hodgson independently on 1 September 1859 by projecting the image of the solar disk produced by an optical telescope through a broad-band filter.[37][38] It was an extraordinarily intense white light flare, a flare emitting a high amount of light in the visual spectrum.[37]

Since flares produce copious amounts of radiation at H-alpha,[39] adding a narrow (≈1 Å) passband filter centered at this wavelength to the optical telescope allows the observation of not very bright flares with small telescopes. For years Hα was the main, if not the only, source of information about solar flares. Other passband filters are also used.

Radio observations

During World War II, on February 25 and 26, 1942, British radar operators observed radiation that Stanley Hey interpreted as solar emission. Their discovery did not go public until the end of the conflict. The same year Southworth also observed the Sun in radio, but as with Hey, his observations were only known after 1945. In 1943, Grote Reber was the first to report radioastronomical observations of the Sun at 160 MHz. The fast development of radioastronomy revealed new peculiarities of the solar activity like storms and bursts related to the flares. Today, ground-based radiotelescopes observe the Sun from c. 15 MHz up to 400 GHz.

Space telescopes

Because the Earth's atmosphere absorbs much of the electromagnetic radiation emitted by the Sun with wavelengths shorter than 300 nm, space-based telescopes allowed for the observation of solar flares in previously unobserved high-energy spectral lines. Since the 1970s, the GOES series of satellites have been continuously observing the Sun in soft X-rays, and their observations have become the standard measure of flares, diminishing the importance of the H-alpha classification. Additionally, space-based telescopes allow for the observation of extremely long wavelengths—as long as a few kilometres—which cannot propagate through the ionosphere.

Examples of large solar flares

Space weather—March 2012.[40]

The most powerful flare ever observed is thought to be the flare associated with the 1859 Carrington Event.[41] While no soft X-ray measurements were made at the time, the magnetic crochet associated with the flare was recorded by ground-based magnetometers allowing the flare's strength to be estimated after the event. Using these magnetometer readings, its soft X-ray class has been estimated to be greater than X10.[42] The soft X-ray class of the flare has also been estimated to be around X50.[43][44]

In modern times, the largest solar flare measured with instruments occurred on 4 November 2003. This event saturated the GOES detectors, and because of this its classification is only approximate. Initially, extrapolating the GOES curve, it was estimated to be X28.[45] Later analysis of the ionospheric effects suggested increasing this estimate to X45.[46] This event produced the first clear evidence of a new spectral component above 100 GHz.[47]

In 2015, Juan José Curto, alongside his colleagues, estimated the Carrington Event and 2003 event to be at least X45,[48] confirming these estimates in a 2019 review.[49]

Other large solar flares also occurred on 2 April 2001 (X20+),[50] 28 October 2003 (X17.2+ and 10),[51] 7 September 2005 (X17),[50] 9 August 2011 (X6.9),[52] 7 March 2012 (X5.4),[53] 6 September 2017 (X9.3),[54][55] 31 December 2023 (X5),[56], 22 February 2024 (X6.3), and 14 May 2024 (X8.7).[57]

Prediction

Current methods of flare prediction are problematic, and there is no certain indication that an active region on the Sun will produce a flare. However, many properties of sunspots and active regions correlate with flaring. For example, magnetically complex regions (based on line-of-sight magnetic field) called delta spots produce the largest flares. A simple scheme of sunspot classification due to McIntosh, or related to fractal complexity[58] is commonly used as a starting point for flare prediction.[59] Predictions are usually stated in terms of probabilities for occurrence of flares above M- or X-class within 24 or 48 hours. The U.S. National Oceanic and Atmospheric Administration (NOAA) issues forecasts of this kind.[60] MAG4 was developed at the University of Alabama in Huntsville with support from the Space Radiation Analysis Group at Johnson Space Flight Center (NASA/SRAG) for forecasting M- and X-class flares, CMEs, fast CME, and Solar Energetic Particle events.[61] A physics-based method that can predict imminent large solar flares was proposed by Institute for Space-Earth Environmental Research (ISEE), Nagoya University.[62]

See also

References

  1. ^ a b "Solar Flares (Radio Blackouts)". NOAA/NWS Space Weather Prediction Center. Retrieved 11 November 2021.
  2. ^ a b Woods, Thomas N.; Kopp, Greg; Chamberlin, Phillip C. (2006). "Contributions of the solar ultraviolet irradiance to the total solar irradiance during large flares". Journal of Geophysical Research. 111 (A10). Bibcode:2005AGUFMSA33A..07W. doi:10.1029/2005JA011507.
  3. ^ Ishikawa, Shin-nosuke; Glesener, Lindsay; Krucker, Säm; Christe, Steven; Buitrago-Casas, Juan Camilo; Narukage, Noriyuki; Vievering, Juliana (2017). "Detection of nanoflare-heated plasma in the solar corona by the FOXSI-2 sounding rocket". Nature Astronomy. 1 (11): 771–774. doi:10.1038/s41550-017-0269-z. ISSN 2397-3366.
  4. ^ Sigalotti, Leonardo Di G.; Cruz, Fidel (2023). "Unveiling the mystery of solar-coronal heating". pubs.aip.org. doi:10.1063/pt.3.5217. Retrieved 2024-05-17.
  5. ^ Fletcher, L.; Dennis, B. R.; Hudson, H. S.; Krucker, S.; Phillips, K.; Veronig, A.; Battaglia, M.; Bone, L.; Caspi, A.; Chen, Q.; Gallagher, P.; Grigis, P. T.; Ji, H.; Liu, W.; Milligan, R. O.; Temmer, M. (September 2011). "An Observational Overview of Solar Flares" (PDF). Space Science Reviews. 159 (1–4): 19–106. arXiv:1109.5932. Bibcode:2011SSRv..159...19F. doi:10.1007/s11214-010-9701-8. S2CID 21203102.
  6. ^ Morimoto, Tarou; Kurokawa, Hiroki (31 May 2002). Effects of Magnetic and Gravity forces on the Acceleration of Solar Filaments and Coronal Mass Ejections (PDF). 地球惑星科学関連学会2002年合同大会. Tokyo. Archived from the original (PDF) on 11 June 2011. Retrieved 8 October 2009.
  7. ^ Tandberg-Hanssen, E.; Martin, Sara F.; Hansen, Richard T. (March 1980). "Dynamics of flare sprays". Solar Physics. 65 (2): 357–368. Bibcode:1980SoPh...65..357T. doi:10.1007/BF00152799. ISSN 0038-0938. S2CID 122385884.
  8. ^ "Biggest Solar Flare on Record". Visible Earth. NASA. 15 May 2001.
  9. ^ a b "NOAA Space Weather Scales". NOAA/NWS Space Weather Prediction Center. Retrieved 20 November 2021.
  10. ^ Rieger, E.; Share, G. H.; Forrest, D. J.; Kanbach, G.; Reppin, C.; Chupp, E. L. (1984). "A 154-day periodicity in the occurrence of hard solar flares?". Nature. 312 (5995): 623–625. Bibcode:1984Natur.312..623R. doi:10.1038/312623a0. S2CID 4348672.
  11. ^ Kurochka, L. N. (April 1987). "Energy distribution of 15,000 solar flares". Astronomicheskii Zhurnal. 64: 443. Bibcode:1987AZh....64..443K.
  12. ^ Crosby, Norma B.; Aschwanden, Markus J.; Dennis, Brian R. (February 1993). "Frequency distributions and correlations of solar X-ray flare parameters". Solar Physics. 143 (2): 275–299. Bibcode:1993SoPh..143..275C. doi:10.1007/BF00646488.
  13. ^ Li, Y. P.; Gan, W. Q.; Feng, L. (March 2012). "Statistical analyses on thermal aspects of solar flares". The Astrophysical Journal. 747 (2): 133. Bibcode:2012ApJ...747..133L. doi:10.1088/0004-637X/747/2/133.
  14. ^ Aschwanden, Markus J. (2011). Self-Organized Criticality in Astrophysics: The Statistics of Nonlinear Processes in the Universe. Berlin, Heidelberg: Springer. ISBN 978-3-642-15001-2.
  15. ^ Reep, Jeffrey W.; Knizhnik, Kalman J. (3 April 2019). "What Determines the X-Ray Intensity and Duration of a Solar Flare?". The Astrophysical Journal. 874 (2): 157. arXiv:1903.10564. Bibcode:2019ApJ...874..157R. doi:10.3847/1538-4357/ab0ae7. S2CID 85517195.
  16. ^ Reep, Jeffrey W.; Barnes, Will T. (October 2021). "Forecasting the Remaining Duration of an Ongoing Solar Flare". Space Weather. 19 (10). arXiv:2103.03957. Bibcode:2021SpWea..1902754R. doi:10.1029/2021SW002754. S2CID 237709521.
  17. ^ Brian, Handy; Hudson, Hugh (14 July 2000). "Super Regions". Montana State University Solar Physics Group. Retrieved 23 December 2021.
  18. ^ a b Livshits, M. A.; Urnov, A. M.; Goryaev, F. F.; Kashapova, L. K.; Grigor’eva, I. Yu.; Kal’tman, T. I. (October 2011). "Physics of post-eruptive solar arcades: Interpretation of RATAN-600 and STEREO spacecraft observations". Astronomy Reports. 55 (10): 918–927. Bibcode:2011ARep...55..918L. doi:10.1134/S1063772911100064. S2CID 121487634. Retrieved 23 December 2021.
  19. ^ Grechnev, V. V.; Kuzin, S. V.; Urnov, A. M.; Zhitnik, I. A.; Uralov, A. M.; Bogachev, S. A.; Livshits, M. A.; Bugaenko, O. I.; Zandanov, V. G.; Ignat’ev, A. P.; Krutov, V. V.; Oparin, S. N.; Pertsov, A. A.; Slemzin, V. A.; Chertok, I. M.; Stepanov, A. I. (July 2006). "Long-lived hot coronal structures observed with CORONAS-F/SPIRIT in the Mg XII line". Solar System Research. 40 (4): 286–293. Bibcode:2006SoSyR..40..286G. doi:10.1134/S0038094606040046. S2CID 121291767. Retrieved 23 December 2021.
  20. ^ Savage, Sabrina L.; McKenzie, David E. (1 May 2011). "Quantitative Examination of a Large Sample of Supra-Arcade Downflows in Eruptive Solar Flares". The Astrophysical Journal. 730 (2): 98. arXiv:1101.1540. Bibcode:2011ApJ...730...98S. doi:10.1088/0004-637x/730/2/98. S2CID 119273860.
  21. ^ Zhu, Chunming; Liu, Rui; Alexander, David; McAteer, R. T. James (19 April 2016). "Observation of the Evolution of a Current Sheet in a Solar Flare". The Astrophysical Journal. 821 (2): L29. arXiv:1603.07062. Bibcode:2016ApJ...821L..29Z. doi:10.3847/2041-8205/821/2/L29.
  22. ^ Priest, E. R.; Forbes, T. G. (2002). "The magnetic nature of solar flares". The Astronomy and Astrophysics Review. 10: 314–317.
  23. ^ Holman, Gordon D. (1 April 2006). "The Mysterious Origins of Solar Flares". Scientific American. Retrieved 17 October 2023.
  24. ^ Ryan, James M.; Lee, Martin A. (1991-02-01). "On the Transport and Acceleration of Solar Flare Particles in a Coronal Loop". The Astrophysical Journal. 368: 316. doi:10.1086/169695. ISSN 0004-637X.
  25. ^ Garner, Rob (6 September 2017). "Sun Erupts With Significant Flare". NASA. Retrieved 2 June 2019.
  26. ^ Schrijver, Carolus J.; Siscoe, George L., eds. (2010), Heliophysics: Space Storms and Radiation: Causes and Effects, Cambridge University Press, p. 375, ISBN 978-1107049048.
  27. ^ Pietrow, A. G. M. (2022). Physical properties of chromospheric features: Plage, peacock jets, and calibrating it all (PhD). Stockholm, Sweden: Stockholm University. doi:10.13140/RG.2.2.36047.76968.
  28. ^ Tandberg-Hanssen, Einar; Emslie, A. Gordon (1988). The Physics of Solar Flares. Cambridge University Press.
  29. ^ "Space Weather Glossary". NOAA/NWS Space Weather Prediction Center. Retrieved 18 April 2022.
  30. ^ "The duration of solar flares". Solar-Terrestrial Centre of Excellence. Retrieved 18 April 2022.
  31. ^ "The Impact of Flares". RHESSI Web Site. NASA. Retrieved 23 December 2021.
  32. ^ Thompson, Richard. "A Solar Flare Effect". Australian Bureau of Meteorology Space Weather Forecasting Centre. Retrieved 12 May 2022.
  33. ^ Curto, Juan José (2020). "Geomagnetic solar flare effects: a review". Journal of Space Weather and Space Climate. 10: 27. Bibcode:2020JSWSC..10...27C. doi:10.1051/swsc/2020027. S2CID 226442270.
  34. ^ Whittaker, Ian. "The invisible space killers – The dangers of space radiation from both inside and outside the solar system". Physiology News Magazine. doi:10.36866/pn.117.36. S2CID 214067105. Retrieved 14 June 2022.
  35. ^ Winckler, J. R. (1964-01-01). "Energetic X-Ray Bursts From Solar Flares". NASA Special Publication. 50: 117.
  36. ^ Carrington, R. C. (November 1859). "Description of a Singular Appearance seen in the Sun on September 1, 1859". Monthly Notices of the Royal Astronomical Society. 20: 13–15. Bibcode:1859MNRAS..20...13C. doi:10.1093/mnras/20.1.13.
  37. ^ a b Carrington, Richard C. (November 1859). "Description of a singular appearance seen in the Sun on September 1, 1859". Monthly Notices of the Royal Astronomical Society. 20 (1): 13–15. Bibcode:1859MNRAS..20...13C. doi:10.1093/mnras/20.1.13.
  38. ^ Hodgson, Richard (November 1859). "On a curious Appearance seen in the Sun". Monthly Notices of the Royal Astronomical Society. 20 (1): 15–16.
  39. ^ Druett, Malcolm; Scullion, Eamon; Zharkova, Valentina; Matthews, Sarah; Zharkov, Sergei; Rouppe Van der Voort, Luc (2017-06-27). "Beam electrons as a source of Hα flare ribbons". Nature Communications. 8 (1). doi:10.1038/ncomms15905. ISSN 2041-1723. PMC 5490266. PMID 28653670.
  40. ^ "Extreme Space Weather Events". National Geophysical Data Center. Archived from the original on May 22, 2012. Retrieved May 21, 2012.
  41. ^ Bell, Trudy E.; Phillips, Tony (6 May 2008). "A Super Solar Flare". Science News. NASA Science. Archived from the original on 12 April 2010. Retrieved 22 December 2012.
  42. ^ Cliver, E. W.; Svalgaard, L. (October 2004). "The 1859 Solar–Terrestrial Disturbance And the Current Limits of Extreme Space Weather Activity". Solar Physics. 224 (1–2): 407–422. Bibcode:2004SoPh..224..407C. doi:10.1007/s11207-005-4980-z. S2CID 120093108.
  43. ^ Woods, Tom. "Solar Flares" (PDF). Archived (PDF) from the original on 23 October 2015. Retrieved 24 November 2019.
  44. ^ Cliver, Edward W.; Dietrich, William F. (4 April 2013). "The 1859 space weather event revisited: limits of extreme activity" (PDF). J. Space Weather Space Clim. doi:10.1051/swsc/2013053. Retrieved 31 December 2023.
  45. ^ "X-Whatever Flare! (X 28)". SOHO Hotshots. ESA/NASA. 4 November 2003. Retrieved 21 May 2012.
  46. ^ "Biggest ever solar flare was even bigger than thought | SpaceRef – Your Space Reference". SpaceRef. 2004-03-15. Archived from the original on 2012-09-10. Retrieved May 21, 2012.
  47. ^ Kaufmann, Pierre; Raulin, Jean-Pierre; de Castro, C. G. Gimnez; Levato, Hugo; Gary, Dale E.; Costa, Joaquim E. R.; Marun, Adolfo; Pereyra, Pablo; Silva, Adriana V. R.; Correia, Emilia (10 March 2004). "A New Solar Burst Spectral Component Emitting Only in the Terahertz Range". The Astrophysical Journal. 603 (2): L121–L124. Bibcode:2004ApJ...603L.121K. doi:10.1086/383186. S2CID 54878789.
  48. ^ Curto, Juan José; Castell, Josep; Moral, Ferran Del (2016). "Sfe: waiting for the big one". Journal of Space Weather and Space Climate. 6: A23. doi:10.1051/swsc/2016018. ISSN 2115-7251.
  49. ^ Curto, Juan José (2020). "Geomagnetic solar flare effects: a review". Journal of Space Weather and Space Climate. 10: 27. doi:10.1051/swsc/2020027. ISSN 2115-7251.
  50. ^ a b "Biggest Solar X-Ray Flare on Record – X20". SOHO Hotshots. ESA/NASA. Retrieved 21 May 2012.
  51. ^ "X 17.2 and 10.0 Flares! (October 28, 2003)". SOHO Hotshots. ESA/NASA. 28 October 2008. Retrieved 21 May 2012.
  52. ^ Fox, Karen C.; Hendrix, Susan (9 August 2011). "Sun Unleashes X6.9 Class Flare". NASA. Archived from the original on 22 October 2011.
  53. ^ Fox, Karen C. (9 March 2012). "Geomagnetic Storm Strength Increases". NASA. Archived from the original on 3 May 2023. Retrieved 9 July 2012.
  54. ^ "Two significant solar flares imaged by NASA's SDO". Phys.org. 6 September 2017. Retrieved 17 October 2023.
  55. ^ "Two Significant Solar Flares Imaged by NASA's SDO". 6 September 2017. Archived from the original on 7 September 2017. Retrieved 6 September 2017.
  56. ^ Bink, Addy (2024-01-01). "'Strongest' solar flare since 2017 detected: Here's what to know". The Hill. Retrieved 2024-02-16.
  57. ^ "Strongest Flare of the Current Solar Cycle | NOAA / NWS Space Weather Prediction Center". www.swpc.noaa.gov. Retrieved 2024-02-23.
  58. ^ McAteer, James (2005). "Statistics of Active Region Complexy". The Astrophysical Journal. 631 (2): 638. Bibcode:2005ApJ...631..628M. doi:10.1086/432412.
  59. ^ Wheatland, M. S. (2008). "A Bayesian approach to solar flare prediction". The Astrophysical Journal. 609 (2): 1134–1139. arXiv:astro-ph/0403613. Bibcode:2004ApJ...609.1134W. doi:10.1086/421261. S2CID 10273389.
  60. ^ "Forecasts". NOAA/NWS Space Weather Prediction Center. Retrieved 17 October 2023.
  61. ^ Falconer, David; Barghouty, Abdulnasser F.; Khazanov, Igor; Moore, Ron (April 2011). "A tool for empirical forecasting of major flares, coronal mass ejections, and solar particle events from a proxy of active-region free magnetic energy". Space Weather. 9 (4). Bibcode:2011SpWea...9.4003F. doi:10.1029/2009SW000537. hdl:2060/20100032971.
  62. ^ Kusano, Kanya; Iju, Tomoya; Bamba, Yumi; Inoue, Satoshi (July 31, 2020). "A physics-based method that can predict imminent large solar flares". Science. 369 (6503): 587–591. Bibcode:2020Sci...369..587K. doi:10.1126/science.aaz2511. PMID 32732427.
{{bottomLinkPreText}} {{bottomLinkText}}
Solar flare
Listen to this article

This browser is not supported by Wikiwand :(
Wikiwand requires a browser with modern capabilities in order to provide you with the best reading experience.
Please download and use one of the following browsers:

This article was just edited, click to reload
This article has been deleted on Wikipedia (Why?)

Back to homepage

Please click Add in the dialog above
Please click Allow in the top-left corner,
then click Install Now in the dialog
Please click Open in the download dialog,
then click Install
Please click the "Downloads" icon in the Safari toolbar, open the first download in the list,
then click Install
{{::$root.activation.text}}

Install Wikiwand

Install on Chrome Install on Firefox
Don't forget to rate us

Tell your friends about Wikiwand!

Gmail Facebook Twitter Link

Enjoying Wikiwand?

Tell your friends and spread the love:
Share on Gmail Share on Facebook Share on Twitter Share on Buffer

Our magic isn't perfect

You can help our automatic cover photo selection by reporting an unsuitable photo.

This photo is visually disturbing This photo is not a good choice

Thank you for helping!


Your input will affect cover photo selection, along with input from other users.

X

Get ready for Wikiwand 2.0 🎉! the new version arrives on September 1st! Don't want to wait?