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

Aleksandr Borovik; Anton Zhdanov

doi:doi:10.12737/22486

UDC 52

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

Published в Solnechno-Zemnaya Fizika · Volume 3, Issue 1, 2017 · Pages 34–45 · Rubrics: Results of current research

DOI 10.12737/22486

Received: 08.11.2016 Accepted: 08.11.2016 Published: 08.11.2016 Language of publication: RUS

Authors

Aleksandr Borovik ¹ iD · Anton Zhdanov ² iD

1 Institute of Solar Terrestrial Physics SB RAS
Irkutsk, Russian Federation

2 Institute of Solar Terrestrial Physics SB RAS
Irkutsk, Russian Federation

ABSTRACT

An electronic database has been created for 123801 solar flares that occurred on the Sun over the period from 1972 to 2010. It is based on catalogs of the Solar Geophysical Data (SGD) and Quarterly Bulletin on Solar Activity. A software package has been used for statistical data preprocessing. The first results revealed a number of new features in the distribution of parameters of solar flares, which differ from those obtained previously. We have found that more than 90 % of all solar flares are low-power. The most numerous class comprises SF flares (64 %). Flare activity shows a pronounced cyclicity and high correlation with Wolf numbers. The highest correlation coefficients indicate S and 1 solar flares. There is also a high correlation between individual flare classes: S and 1, 1 and (2–4). The results obtained previously [Mitra et al., 1972] which provide evidence of the prevalence of SN solar flares (47 %) and the existence of significant peaks for SN and 1N flares, have not been confirmed. The distri-bution of the number of solar flares with increasing op-tical importance smoothly decreases without significant deviations. With increasing optical importance, solar flares are gradually redistributed toward an increase in brightness class. The excess of the number of SN and 1N solar flares present in the distributions obtained in [Mitra et al., 1972] are most likely associated with poor statistics.

KEYWORDS

solar activity flares

Information Text References

Authors:

1. Institute of Solar Terrestrial Physics SB RAS

Irkutsk, Russian Federation

2. Institute of Solar Terrestrial Physics SB RAS

Irkutsk, Russian Federation

Type:

Article

Pages:

from 34 to 45

Status:

Published

Subject area:

UDC 52

Language:

Russian, English

Keywords:

solar activity, flares

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ВВЕДЕНИЕ

Пространственные и временные параметры солнечных вспышек в оптическом диапазоне длин волн были подробно изучены еще в годы становления международного вспышечного патруля, в период комплексного изучения глобальных геофизических процессов в рамках международных программ МГГ. Наблюдения велись в линиях Нα, Н и К СаII и в меньшей степени в других бальмеровских линиях. Патруль проводился в основном в линии Нα (λ=6563 Å). Большинство станций использовали разные по своим оптическим характеристикам приборы и инструменты: спектрогелиографы (спектрогелиоскопы), фильтры Лио с полосой пропускания от 0.5 до 0.75 Å. Не все станции применяли автоматическую киносъемку и стандартизованные методы измерений.

По первой, введенной в 1956 г. международной классификации солнечные вспышки делились по баллам в зависимости от площади участка хромо-сферы, охваченного вспышкой. В 1966 г. была введена новая классификация, согласно которой балл вспышки определялся по полной энергии W, излучаемой в линии Нα:

References

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

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