Results 11 to 20 of about 1,057 (192)
Change of Sunspot Groups Observed from 2002 to 2011 at ButterStar Observatory [PDF]
Journal of Astronomy and Space Sciences, 2012 Since the development of surface magnetic features should reflect the evolution of the solar magnetic field in the deep interior of the Sun, it is crucial to study properties of sunspots and sunspot groups to understand the physical processes working ...
Sung-Jin Oh, Heon-Young Chang
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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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Properties of sunspots in cycle 23 [PDF]
Astronomy & Astrophysics, 2007 In this paper we investigate the dependence of umbral core brightness, as well as the mean umbral and penumbral brightness on the phase of the solar cycle and on the size of the sunspot. Albregtsen & Maltby (1978) reported an increase in umbral core brightness from the early to the late phase of solar cycle from the analysis of 13 sunspots which ...
Mathew, S. +3 more
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Frequency of Solar Spotless Days and Flare Index as Indices of Solar Cycle Activity [PDF]
Journal of Astronomy and Space Sciences, 2014 There was a research on the prolongation of solar cycle 23 by the solar cyclic variation of solar, interplanetary geomagnetic parameters by Oh & Kim (2013).
Suyeon Oh
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The lost sunspot cycle: Reanalysis of sunspot statistics [PDF]
Astronomy & Astrophysics, 2003 We have recently suggested that one low sunspot cycle was possibly lost in 1790s (Usoskin et al. 2001, A&A, 370, L31). In this paper we present the results of a rigorous statistical analysis of all available sunspot observations around the suggested additional cycle minimum in 1792-1793.
I. G. Usoskin +2 more
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Legal restrictions, “sunspots,” and cycles [PDF]
Journal of Economic Theory, 1989 zbMATH Open Web Interface contents unavailable due to conflicting licenses.
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A Representation of the Sunspot Cycle* [PDF]
Bell System Technical Journal, 1939 ALTHOUGH sunspots had been observed occasionally back to ancient times, their study may be said to date from their rediscovery by Galileo in the spring of 1610 with the then newly invented telescope. Since then much has been written about their nature, their periodicities and possible influence on human affairs.
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An upper limit prediction of the peak sunspot number for solar cycle 24
Journal of Space Weather and Space Climate, 2011 In this paper we address the prediction of the maximum sunspot number in solar cycle 24. We correlate the integral sunspot activity related to the variability of the cycle decrease speed in the declining phase with the height of the next sunspot maximum.
Van der Linden R., Podladchikova T.
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Prediction of solar activity on the basis of spectral characteristics of sunspot number [PDF]
Annales Geophysicae, 2004 Prediction of solar activity strength for solar cycles 23 and 24 is performed on the basis of extrapolation of sunspot number spectral components. Sunspot number data during 1933-1996 periods (solar cycles 17-22) are searched for periodicities by ...
E. Echer +4 more
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Differential Rotation for Different-sized Sunspot Groups Early Observed by the OGAUC
The Astrophysical Journal, 2023 Solar differential rotation is an important ingredient of the solar dynamo model, not only because the solar rotation profile is one of the key inputs in a solar dynamo model, but also because it imposes constraints for the solar dynamo model.
Miao Wan +3 more
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