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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…

We use Sun-as-a-star helioseismology data, collected by the Birmingham Solar-Oscillations Network (BiSON), to examine the relationship between the solar-cycle-induced frequency shifts of whole-Sun, low-angular degree solar p modes and…

Solar and Stellar Astrophysics · Physics 2026-05-29 William J. Chaplin , Sarbani Basu , Rachel Howe , Yvonne Elsworth , Steven J. Hale , Eleanor Murray

We use helioseismic data from ground and space-based instruments to analyze how solar rotation has changed since the beginning of solar Cycle 23 with emphasis on studying the differences between Cycles 23 and 24. We find that the nature of…

Solar and Stellar Astrophysics · Physics 2019-10-02 Sarbani Basu , H. M. Antia

We have measured the meridional motions of the magnetic elements in the Sun's surface layers since 1996 and find systematic and substantial variations. In general the meridional flow speed is fast at cycle minima and slow at cycle maxima.…

Solar and Stellar Astrophysics · Physics 2015-06-19 David H. Hathaway , Lisa Upton

We study the response of the low-degree, solar p-mode frequencies to the unusually extended minimum of solar surface activity since 2007. A total of 4768 days of observations collected by the space-based, Sun-as-a-star helioseismic GOLF…

Solar and Stellar Astrophysics · Physics 2015-05-13 D. Salabert , R. A. García , P. L. Pallé , S. J. Jiménez-Reyes

We describe systematic changes in the centroid frequencies and the splitting coefficients as found using data from MDI on board SOHO, covering cycle 23. The data allow us to construct a seismic map of the evolving solar activity -- covering…

Astrophysics · Physics 2007-05-23 W. A. Dziembowski , Philip R. Goode

Rotation of the large scale solar magnetic field has a great importance for the understanding of solar dynamic, for the search of longitidinal structure and for the study of solar-terrestrial relations. 30-year long observations taken at…

Solar and Stellar Astrophysics · Physics 2018-02-08 E. A. Gavryuseva

We have used solar oscillation frequencies and frequency splittings obtained over solar cycles 23, 24 and the rising phase of solar cycle 25 to investigate whether the tachocline properties (jump i.e., the change in the rotation rate across…

Solar and Stellar Astrophysics · Physics 2024-10-04 Sarbani Basu , Wesley Antônio Machado Andrade de Aguiar , Sylvain G. Korzennik

High quality observations of the low-degree acoustic modes (p-modes) exist for almost two complete solar cycles using the solar spectrophotometer Mark-I, located at the Observatorio del Teide (Tenerife, Spain) and operating now as part of…

Astrophysics · Physics 2016-08-16 S. J. Jiménez-Reyes , T. Corbard , P. L. Pallé , T. Roca Cortés , S. Tomczyk

Using both wavelet and Fourier analysis, a study has been undertaken of the changes in the quasi-periodic variations in solar photospheric fields in the build-up to one of the deepest solar minima experienced in the past 100 years. This…

Solar and Stellar Astrophysics · Physics 2015-06-15 Susanta Kumar Bisoi , P. Janardhan , D. Chakrabarty , S. Ananthakrishnan , Ankur Divekar

The meridional circulation of the solar magnetic fields in Solar Cycles 21-24 was considered. Data from both ground-based and space observatories were used. Three types of time-latitude distributions of photospheric magnetic fields and…

Solar and Stellar Astrophysics · Physics 2023-11-17 Irina A. Bilenko

The Sun's polar magnetic fields are directly related to solar cycle variability. The strength of the polar fields at the start (minimum) of a cycle determine the subsequent amplitude of that cycle. In addition, the polar field reversals at…

Solar and Stellar Astrophysics · Physics 2014-08-01 Lisa Upton , David H. Hathaway

Convection, differential rotation, and meridional circulation of solar plasma are studied based on helioseismic data covering the period from May 2010 to August 2024, significantly prolonged compared to that previously considered. Depth…

Solar and Stellar Astrophysics · Physics 2025-04-22 A. V. Getling , A. G. Kosovichev

The results of determinations of the azimuthal and meridional velocities by time-distance helioseismology from Helioseismic and Magnetic Imager (HMI) onboard Solar Dynamics Observatory (SDO) from May 2010 to September 2020 at latitudes from…

Solar and Stellar Astrophysics · Physics 2021-02-26 Alexander V. Getling , Alexander G. Kosovichev , Junwei Zhao

The availability of continuous helioseismic data for two consecutive solar minima has provided a unique opportunity to study the changes in the solar interior that might have led to this unusual minimum. We present preliminary analysis of…

Solar and Stellar Astrophysics · Physics 2010-02-12 Kiran Jain , S. C. Tripathy , O. Burtseva , I. Gonzalez Hernandez , F. Hill , R. Howe , S. Kholikov , R. Komm , J. Leibacher

The last solar minimum was, by recent standards, unusually deep and long. We are now close to the maximum of the subsequent solar cycle, which is relatively weak. In this article we make comparisons between different global (unresolved)…

Solar and Stellar Astrophysics · Physics 2015-07-13 A. -M. Broomhall , V. M. Nakariakov

Solar subsurface zonal and meridional-flow profiles during the rising phase of solar cycle 24 are studied using time-distance helioseismology technique. The faster zonal bands in the torsional-oscillation pattern show strong hemispheric…

Solar and Stellar Astrophysics · Physics 2015-06-19 Junwei Zhao , A. G. Kosovichev , R. S. Bogart

By using the unique database of SOHO/MDI full disk magnetograms from 1996 September to 2011 January, covering the entire solar cycle 23, we analyze the time-variability of the solar magnetic flux spectrum and study the properties of…

Solar and Stellar Astrophysics · Physics 2015-06-18 C. l. Jin , J. X. Wang

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

We study the asymmetric distribution of weak photospheric magnetic field values in the two hemispheres separately using synoptic maps from SDO/HMI, SOLIS/VSM and WSO during solar cycles 21-24. We calculate the weak-field asymmetry (shift)…

Solar and Stellar Astrophysics · Physics 2019-10-09 Tibebu Getachew , Ilpo Virtanen , Kalevi Mursula