Results 21 to 30 of about 9,553 (254)
Evolutionary Relationship between Sunspot Groups and Soft X-Ray Flares over Solar Cycles 21–25
The Astrophysical Journal, 2023 Studying the interaction between solar flares and sunspot groups (SGs) is crucial for understanding and predicting solar activity. We examined the distribution, correlation, and flaring rates in the northern and southern hemispheres to reveal the ...
Jiaqi Lin +5 more
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Digitization of sunspot drawings by Sp\"orer made in 1861-1894 [PDF]
, 2014 Most of our knowledge about the Sun's activity cycle arises from sunspot observations over the last centuries since telescopes have been used for astronomy. The German astronomer Gustav Sp\"orer observed almost daily the Sun from 1861 until the beginning
Arlt, Rainer +2 more
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Solar activity cycle 25: the first three years
Solar-Terrestrial Physics, 2023 We analyze features of current solar activity cycle 25 for the first three years of its development (2020–2022). Compared to cycle 24, the current cycle is shown to exceed the previous one in the number of sunspot groups (1.5 times), the number of flares
Yazev S. A. +2 more
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The Development of Sunspot Groups [PDF]
International Astronomical Union Colloquium, 1993 AbstractIt is shown that the growth and decay rates of sunspot groups are both a function of the axial tilt angles of the groups. Both of these rates reach a maximum near the average tilt angle, which is around +5°, not 0°. (A positive tilt angle represents the situation where the leading spots are equatorward of the following spots).
openaire +1 more source
Active-Region Tilt Angles: Magnetic Versus White-Light Determinations of Joy's Law [PDF]
, 2014 The axes of solar active regions are inclined relative to the east--west direction, with the tilt angle tending to increase with latitude ("Joy's law").
Baranyi, T. +3 more
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Latitude Migration of Sunspot Groups
The Astronomical Journal, 2001 Characteristics of latitude migration of sunspot groups in the northern and southern hemispheres are investigated by using the Royal Greenwich Observatory data set from the years 1874 through 1999. Latitude migration of sunspot groups is found to be represented by a binomial formula, which quantitatively describes the law.
K. J. Li, H. S. Yun, X. M. Gu
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Width of Sunspot Generating Zone and Reconstruction of Butterfly Diagram
, 2010 Based on the extended Greenwich-NOAA/USAF catalogue of sunspot groups it is demonstrated that the parameters describing the latitudinal width of the sunspot generating zone (SGZ) are closely related to the current level of solar activity, and the growth ...
A.J. Conway +20 more
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Sequences of Large Sunspot Groups [PDF]
Symposium - International Astronomical Union, 1976 The concept of a sequence of large sunspot groups is defined. From distribution functions of large groups from the period of sequences and that outside sequences it has been found that there are relatively more groups with a smaller maximum area in the period of sequences than in the period outside sequences.
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The Contribution of Large Recurrent Sunspot Groups to Solar Activity: Empirical Evidence
Universe, 2022 We identify large sunspot nestlets (SN) mostly containing recurrent sunspot groups and investigate the indices of solar activity defined as the 11- or 22-year moving average of the daily areas of the SN. These nestlets, 667 in total, are constructed from
Alexander Shapoval
doaj +1 more source
, 2013 Using the Solar Optical Observing Network (SOON) sunspot-group data for the period 1985-2010, the variations in the annual mean equatorial-rotation rates of the sunspot groups are determined and compared with the known variations in the solar equatorial ...
A. Brandenburg +56 more
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