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The work is devoted to the study of periodic structures in the magnetic field of the photosphere. The polarity of the Sun's magnetic fields shows cyclicity with periods of 1-3 years, which is possibly due to quasi-biennial variations that…

Solar and Stellar Astrophysics · Physics 2025-07-08 Elena Vernova , Marta Tyasto , Dmitrii Baranov

Sunspots are a canonical marker of the Sun's internal magnetic field which flips polarity every ~22-years. The principal variation of sunspots, an ~11-year variation in number, modulates the amount of magnetic field that pierces the solar…

When traveling in the heliosphere, Galactic cosmic rays (GCRs) are subjected to the solar modulation effect, a quasiperiodical change of their intensity caused by the 11-year cycle of solar activity. Here we investigate the association of…

Solar and Stellar Astrophysics · Physics 2022-11-22 Nicola Tomassetti , Bruna Bertucci , Emanuele Fiandrini

We present a method of chromospheric flux simulation for 13 late-type main-sequence stars. These Sun-like stars have well-determined cyclic flux variations similar to 11 yr solar activity cycle. Our flux prediction is based on chromospheric…

Solar and Stellar Astrophysics · Physics 2015-05-20 E. A. Bruevich

The solar magnetic activity cycle is responsible for periodic episodes of severe space weather, which can perturb satellite orbits, interfere with communications systems, and bring down power grids. Much progress has recently been made in…

Astrophysics · Physics 2007-05-23 T. S. Metcalfe , T. J. Henry , M. Knolker , D. R. Soderblom

Numerous analyses suggest the existence of various quasi-periodicities in solar activity. The power spectrum of solar activity recorded in sunspot data is dominated by the $\sim$11-year quasi-periodicity, known as the Schwabe cycle. In the…

Solar and Stellar Astrophysics · Physics 2020-01-08 P. Frick , D. Sokoloff , R. Stepanov , V. Pipin , I. Usoskin

The present study is an attempt to investigate the long term variations in coronal rotation by analyzing the time series of the solar radio emission data at 2.8 GHz frequency for the period 1947 - 2009. Here, daily adjusted radio flux…

Solar and Stellar Astrophysics · Physics 2015-05-27 Satish Chandra , Hari Om Vats

Chromospheric differential rotation is a key component in comprehending the atmospheric coupling between the chromosphere and the photosphere at different phases of the solar cycle. In this study, we therefore utilize the newly calibrated…

It has recently been discovered that the time phases (time-varying delays) of the irregular periodicities observed in the Sunspot series, consisting of the approximate 27-day latitude-averaged plasma rotation and approximate 11-yr magnetic…

Solar and Stellar Astrophysics · Physics 2026-02-24 William A. Gardner , Antonio Napolitano

Studies on the periodic variation and the phase relationship between different solar activity indicators are useful for understanding the long-term evolution of solar activity cycle. Here we report the statistical analysis of grouped solar…

Solar and Stellar Astrophysics · Physics 2020-03-11 Hui Deng , Ying Mei , Feng Wang

Context. The Sun and solar-like stars undergo activity cycles for which the underlying mechanisms are not well understood. The oscillations of the Sun are known to vary with its activity cycle and these changes provide diagnostics on the…

Solar and Stellar Astrophysics · Physics 2017-02-08 René Kiefer , Ariane Schad , Guy Davies , Markus Roth

Chromospheric plages are distributed between mid-latitude and the Equator and never close to the Poles. Therefore, we suspect that the inclination angle of the solar rotation axis has an impact on the observable chromospheric emission. We…

Solar and Stellar Astrophysics · Physics 2024-10-16 G. Vanden Broeck , S. Bechet , G. Rauw , F. Clette

We study the different patterns of interannual magnetic variability in stars on or near the lower main sequence, approximately solar-type (G-K dwarf) stars in time series of 36 years from the Mount Wilson Observatory Ca\,{\sc ii}\,H\&K…

Solar and Stellar Astrophysics · Physics 2016-06-22 K. Oláh , Zs. Kővári , K. Petrovay , W. Soon , S. Baliunas , Z. Kolláth , K. Vida

We use 9.5-yr of BiSON Sun-as-a-star data to search for dependence of solar-cycle parameter changes on the angular degree, l, of the data. The nature of the Sun-as-a-star observations is such that for changes measured at fixed frequency, or…

Astrophysics · Physics 2009-11-11 D. Salabert , W. J. Chaplin , Y. Elsworth , R. New , G. A Verner

The evolution of the solar activity comprises, apart from the well-known 11-year cycle, various temporal scales ranging from months up to the secondary cycles known as mid-term oscillations. Its nature deserves a physical explanation. In…

Solar and Stellar Astrophysics · Physics 2020-08-04 D. D. Sokoloff , A. S. Shibalova , V. N. Obridko , V. V. Pipin

Irradiance variability has been monitored from space for more than two decades. Even if data are coming from different sources, it is well established that a temporal variability exists which can be set to as approximately 0.1%, in phase…

Astrophysics · Physics 2009-11-11 J. P. Rozelot , S. Lefebvre , S. Pireaux , A. Ajabshirizadeh

The solar magnetic activity consists of two periodic components: the main cycle with a period of 11 yr and a shorter cycle with a period of ~2 yrs. The origin of this second periodicity is still not well understood. We use almost 15 yrs of…

Solar and Stellar Astrophysics · Physics 2015-06-11 R. Simoniello , K. Jain , S. C. Tripathy , S. Turck-Chieze , W. Finsterle , M. Roth

Using the non-linear mean-field dynamo models we calculate the magnetic cycle parameters, like the dynamo cycle period, the amplitude of the total magnetic energy, and the Poynting flux luminosity from the surface for the solar analogs with…

Solar and Stellar Astrophysics · Physics 2021-01-27 V. V. Pipin

This study depends on KIC 9641031 eclipsing binary system with a chromospherically active component. There are three type variations, such as geometrical variations due to eclipses, sinusoidal variations due to the rotational modulations…

Solar and Stellar Astrophysics · Physics 2016-05-04 Ezgi Yoldaş , Hasan Ali Dal

In addition to the well-known 11-year solar cycle, the Sun's magnetic activity also shows significant variation on shorter time scales, e.g. between one and two years. We observe a quasi-biennial (2-year) signal in the solar p-mode…