Bulletin of Taras Shevchenko National University of Kyiv. Astronomy, no. 55, p. 20-22 (2017)

Double Hale’s cycle in changes of sunspot diameters. Preliminary results

V. Lozitsky, Dr. Sci.,
V. Efimenko, Ph. D.,
Astronomical Observatory of Taras Shevchenko National University of Kyiv, Kyiv

Integral distributions for diameters of sunspots are analyzed in cycles Nos. 12–24. For determination of index of integral distribution α, the large sunspots of 50–90 Mm are taken into account; all data are averaged for each 11-year cycle for better accuracy. The main results are following: (a) the mean value of α index is 5.4 for last 13 cycles; (b) secular trend in changes of α index is absent, and (c) there are reliable evidences of double Hale’s cycle (about 44 years). In particular, the lowest values of α index were found for cycles Nos. 14, 17–18 and 22. Since this index reflects the dispersion of sunspot diameters, obtained results indicate that convective zone of the Sun generates the embryos of active regions in different statistical regimes which change with cycle about 44 years.

Key words
Sun, solar activity, sunspots, integral distribution for diameters of sunspots, double Hale’s cycle

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DOI: https://doi.org/10.17721/BTSNUA.2017.55.20-22