Statistical studies of low-power solar flares. Distribution of flares by area, brightness, and classes

2018

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Abstract. This paper is a sequel to papers dealing with time parameters of solar flares in the Hα line. Using data from the international flare patrol for 1972-2010, we have determined the mean duration of flares of different importance and classes of area. We have established that 94.6 % of flares last more than 60 min. The duration of 90 % of flares with 60 t > min is 2.1-3.3 hrs. In rare cases, flares can last about 12 hrs. The duration of powerful solar flares does not exceed 8.3 hrs.We have found that the duration of solar flares depends on features of their development. Flares with one brilliant point in the flare region have the shortest duration; two-ribbon flares and flares exhibiting several intensity maxima have the longest duration. We have confirmed that the duration of flares increases with increasing classes of area and brightness.

Section: Figure 6 Variations In Statistical Distribution Parameters mentioning

confidence: 63%

Section: Duration Of Solar Flares According To Data From All Stationsmentioning

confidence: 99%

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Statistical studies of duration of low-power solar flares

Borovik¹,

2018

Self Cite

“…As noted by many authors [Abramenko et al, 1960;Warwick, 1965;Smith G., Smith E., 1966Kopetskaya, Kopetsky, 1971Ward et al, 1973;Rossada, 1977;Borovik, Zhdanov, 2017], international flare patrol data suffer from certain heterogeneity. In particular, the time of onset, maximum, and end of a flare may differ in group reports of different stations.…”

Section: Database and Its Analysismentioning

confidence: 99%

“…Special attention is given to low-power flares with an area of less than 2 sq. deg., which constitute the majority (over 90 %) of all solar flares [Borovik, Zhdanov, 2017]. Some studies carried out over the past two decades are presented in [Temmer et al, 2001;Giersch, 2013;Potzi et al, 2014].…”

Section: Introductionmentioning

confidence: 99%

Distribution of low-power solar flares by brightness rise time

Borovik¹,

2018

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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.

Statistical studies of duration of low-power solar flares

Borovik¹,

2018

Self Cite

This paper is a sequel to papers dealing with time parameters of solar flares in the Hα line. Using data from the international flare patrol for 1972–2010, we have determined the mean duration of flares of different importance and classes of area. We have established that 94.6 % of flares last more than 60 min. The duration of 90 % of flares with min is 2.1–3.3 hrs. In rare cases, flares can last about 12 hrs. The duration of powerful solar flares does not exceed 8.3 hrs. We have found that the duration of solar flares depends on features of their development. Flares with one brilliant point in the flare region have the shortest duration; two-ribbon flares and flares exhibiting several intensity maxima have the longest duration. We have confirmed that the duration of flares increases with increasing classes of area and brightness.