On stability of rotation of the mean magnetic field of the Sun

Abstract

Abstract. New data on the mean magnetic field of the Sun (MMFS) as a star measured at the Crimean Astrophysical Observatory in 1998-2001 are presented. The 34-year time series of the MMFS using similar data from three other observatories (1968-2001, with the total number of daily MMFS values N = 12 428), is considered. It is found that (a) the primary synodic period of the equatorial rotation of solar magnetic field, P = 26.929 ± 0.015 days, did not vary over the last 34 years, but (b) the average intensity H 0 of the photospheric large-scale fields, by modulus, decreased by about 4.5% (with a confidence level of about 80%). The conclusion is made that the longer, 90-year, cycle might be responsible for this potential gradual decrease of H 0 . The average curve of MMFS variation as plotted with the primary rotational period P demonstrates an obvious N-S asymmetry of polarities, perhaps associated with the quadrupole component and "magnetic disequilibrium" of the Sun as a whole.

On the Variability of the Solar Mean Magnetic Field: Contributions from Various Magnetic Features on the Surface of the Sun

“…The SMMF exhibits a dominant periodicity of ≈27 days. The analysis by Haneychuk et al (2003) reported that this rotation period does not vary with time, whereas a recent study by Xie et al (2017) suggested that the rotation period of SMMF changes with the phase of the solar cycle. Besides, the amplitude of the SMMF varies slowly on the timescales of the solar cycle: being close to±2G during the sunspot maximum and±0.2G during the minimum of the solar activity (Plachinda et al 2011).…”

Крымские Наблюдения Магнитного Солнца: 1967–2018 Гг.

“…В 1968-1976 гг. двухсекторная структура вращалась с синодическим периодом P = 27.03(6) сут, но с добавлением данных он приблизился к 26.92(2) сут (Haneychuk et al, 2003). В СМ полного 52летнего ряда соответствующий пик когерентного вращения, однако, отсутствует, см.…”

Stellar magnetic fields and measurement techniques

“…На теперiшнiй час каталог вимiрiв загального магнiтного поля Сонця в шести обсерваторiях свiту складає понад 18 тисяч добових значень. За даними спостережень i усередненими вимiрами на чотирьох обсерваторiях середня величина ЗМС складає всього 0.45 Гс, з амплiтудою змiни ЗМС в (0.22 ± 0.03) Гс [20]. Однак, як виявили цi ж дослiдники, пiврiчнi усередненi величини магнiтного поля за 34 роки спостережень показують складнi варiацiї поля в межах бiля ±0.5 Гс синхронно з 11-рiчним циклом сонячної активностi.…”