Near-annual variation of the magnetic Sun
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Over past 51 years (1968–2018) the general magnetic field of the Sun was measured nearly each day by the Crimean Astrophysical Observatory, the Wilcox Solar Observatory and five others. It is shown that the annual variation of this field (longitudinal component), thought to be caused by the inclination of the Sun’s axis to ecliptic, is splitted into two components with periods 0.954(3) years and 1.034(4) years (with mean amplitudes \(\approx 0.044\) G). But while the first one agrees well with the expected period 0.957(4) years (caused by the 11-year polar field reversals and coupled to the yearly projection effect), the second one is shifted relative to its theoretical value, 1.047(4) years, by \(\Delta = 0.013(5)\) years (99% confidence). The beat period of the two observed components, 12.3(7) years, agrees well with the Jovian period 11.9 years, being close also to the length of the 11-year cycle. Since the modern astronomy rejects a planetary influence on the Sun, the origin of both the 1.034-year periodicity and the shift \(\Delta \) remains to be mysterious.
KeywordsThe Sun Photosphere Magnetic field 11-year cycle Solar system
I express deep gratitude to F.M. Sanchez for exciting discussions on the Sun and the solar system, and thank also V.I. Haneychuk and other observers for their GMF data and the reviewer for useful comments.
- Bose, S., Nagaraju, K.: https://www.researchgate.net/publication/325732691 (2018)