Irkutsk, Russian Federation
Irkutsk, Russian Federation
Using data from the international flare patrol for 1972–2010, we have formed an electronic database for more than 123 thousand solar flares. We determined the mean brightness rise time (flash phase) for flare area classes and importance. We show that the mean flash phase increased with increasing area class. For brightness classes this trend is less pronounced. We have found that flares with explosive phase and flares with one brilliant point have the shortest flash phases; two-ribbon flares and flares with several intensity maxima, the longest ones. We have separated 572 cases when the brightness rise time was more than 60 min; 80 % of such ultra-long flares have a shorter brightness decay time (main phase). We have established that low-power flares in terms of developmental features do not differ from large flares. Low-power solar flares, as well as large flares, can be followed by filament activation or disappearance, and can have an explosive phase and several intensity maxima. Two-ribbon flares, white-light flares, and flares covering sunspot umbra can also have low power.
solar activity, solar flares
1. Abramenko, S.I., Dubov E.E., Ogir M.B., Steshenko N.E., Shaposhnikov E.F., Tsap T.T. Photometry of solar flares. Izvestiya Krymskoi astrofizicheskoi observatorii [Bull. Crimean Astrophys. Observatory]. 1960, vol. 23, pp. 341-361. (In Russian).
2. Altas L. Spotless flare activity. Solar Phys. 1994, vol. 151, no. 1, pp. 169-176.
3. Altyntsev A.T., Banin V.G., Kuklin G.V., Tomozov V.M. Solnechnye vspyshki [Solar Flares]. Moscow, Nauka Publ., 1982. 246 p. (In Russian).
4. Barlas O., Altas L. The duration of spotless flares. Astrophys. Space Sci. 1992, vol. 197, no. 2, pp. 337-341. DOI: 10.1007/ BF00645745.
5. Borovik A.V., Myachin D.Yu. The spotless flare of March 16, 1981. I. Pre-flare activations of the chromospheric fine structure. Solar Phys. 2002, vol. 2005, no 1, pp. 105-116.
6. Borovik A.V., Myachin D.Yu. Structure and development of the spotless flare on March 16, 1981. Geomagnetism and Aeronomy. 2010, vol. 50, no. 8, pp. 937-949. DOI: 10.1134/ S0016793210080037.
7. Borovik A.V., Zhdanov A.A. Statistical studies of low-power solar flares. Distributions of flares by area, brightness and classes. Solar-Terr. Phys. 2017, vol. 3, no. 1, pp. 40-56. DOI:https://doi.org/10.12737/article_58f96fda7e3e76.83058648.
8. Borovik A.V., Myachin D.Yu., Tomozov V.M. Observation of spotless solar flares at Baikal Astrophysical Observatory of ISTP SB RAS and their interpretation. Izvestiya Irkutskogo gosudarstvennogo universiteta. Ser. Nauki o Zemle [The Bulletin of the Irkutsk State University. Ser. Earth Sciences]. 2014, vol. 7, no. 1, pp. 23-45. (In Russian).
9. Borovik A.V., Myachin D.Yu., Uralov A.M. Spotless flare model. Izvestiya Krymskoi astrofizicheskoi observatorii [Bull. Crimean Astrophys. Observatory]. 2016, vol. 112, no.1, pp. 38-46. (In Russian).
10. Chistyakov V.F. Spotless flares. Issledovaniya po geomagnetizmu, aeronomii i fizike Solntsa [Res. on Geomagnetism, Aeronomy and Solar Physics]. 1988, iss. 79, pp. 70-75. (In Russian).
11. Dodson H.W., Hedeman E.R., McMath R.R. Photometry of solar flares. Astrophys. J. Suppl. 1956, vol. 2, pp. 241-270.
12. 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. An observational overview of solar flares. Space Sci. Rev. 2011, vol. 159, pp. 19-106. DOI:https://doi.org/10.1007/s11214-010-9701-8.
13. Giersch O. GONG Inter-site Hα flare comparison. J. Phys.: Conf. Ser. 2013, vol. 440, iss. 1, article id. 012006. DOI:https://doi.org/10.1088/1742-6596/440/1/012006.
14. Hirayama T. Theoretical model of flares and prominences. I: evaporating flare model. Solar Phys. 1974, vol. 34, no. 2, pp. 323-338.
15. Hyder C.L. A phenomenological model for disparitions brusques followed by flare-like chromospheric brightenings. Solar Phys. 1967, vol. 2, no. 3, pp. 267-284.
16. Kopetskaya F., Kopetsky M. Characteristics of large chromospheric flares from Frittseva, Kopetsky and Šhvestka Catalogue. Issledovaniya po geomagnetizmu, aeronomii i fizike Solntsa [Res. on Geomagnetism, Aeronomy and Solar Physics]. 1971, iss. 2, pp. 117-130. (In Russian).
17. Kopp R.A., Pneuman G.W. Magnetic reconnection in the corona and the loop prominence phenomenon. Solar Phys. 1976, vol. 50, pp. 85-98.
18. Luo B. The flares of spotless regions. Proc. the Kunming Workshop “Solar Physics and Interplanetary Travelling Phenomena”, November 21-25, 1983, Kunming, China / Eds. de Jager C., Biao Chen. Beijing: Science Press, 1985, vol. 1, p. 718.
19. Potzi W., Veronig A., Riegler G., Amerstorfer U., Pock TH., Temmer M., Polanec W., Baumgartne D.J. Real-time flare detection in groundbased Hα imaging at Kanzelhöhe Observatory. Solar Phys. 2014, vol. 290, no. 3, pp. 951-977.
20. Rossada V.M. Statistical analysis of 6600 flares for 1965-1966. Vestnik Kievskogo gosudarstvennogo universiteta [Bul-
21. letin of Kiev State University. Ser. Astronomy]. 1977, no. 19, pp. 49-55. (In Russian).
22. Smith H., Smith E. Solnechnye vspyshki [Solar Flares] Moscow, Mir Publ., 1966, 426 p. (In Russian). English edition: Smith H.J., Smith E. Solar Flares. Macmillan, 1963. 322 p.
23. Sturrock P.A. Model of the high-energy phase of solar flares. Nature. 1966, vol. 211, pp. 695-697.
24. Švestka Z. Solar Flares. Dordrecht, Holland: D. Reidel, 1976. 415 p.
25. Švestka Z., Dodson-Prince H.W., Martin S.F., Mohler O.C., Moore R.L., Nolte J.T., Petrasso R.D. Study of the postflare loops on 29 July 1973. Solar Phys. 1982, vol. 78, no. 2, pp. 271-285. DOI:https://doi.org/10.1007/BF00151609.
26. Temmer M., Veronig A., Hanslmeier A., Otruba W., Messerotti M. Statistical analysis of solar Hα flares. Astron. Astrophys. 2001, vol. 375, pp. 1049-1061.
27. Warwick C.S. Some characteristics of solar flares. Astrophys. J. 1954, vol. 120, pp. 237-244.
28. Ward F., Cornevall R.F., Hendle R. Solar flare observations from a pair of matched instruments. Solar Phys. 1973, vol. 31, no. 1, pp. 131-141.
29. Yatini C. Y. Characteristics of Hα Flare in the Solar Spotless Area. National Institute of Aeronautics and Space of Indonesia Majalah LAPAN. 2001, vol. 3, p. 53.
