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Related papers: Cyclic Changes of the Sun's Seismic Radius

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We derive formulae connecting the frequency variations in the spectrum of solar oscillations to the dynamical quantities that are expected to change over the solar activity cycle. This is done for both centroids and the asymmetric part of…

Astrophysics · Physics 2009-11-10 W. A. Dziembowski , P. R. Goode

The gradient of rotation in the near-surface shear layer (NSSL) of the Sun provides valuable insights into the dynamics associated with the solar activity cycle and the dynamo. Results obtained with global oscillation mode-splittings lack…

Solar and Stellar Astrophysics · Physics 2024-04-04 M. Cristina Rabello Soares , Sarbani Basu , Richard Bogart

The Sun's magnetic dynamo cycle features a distinct pattern: a propagating region of sunspot emergence appears around 30 degrees latitude and vanishes near the equator every 11 years. Moreover, longitudinal flows called "torsional…

We analyze spectral properties of solar convection in the range of depths from 0 to 19~Mm using subsurface flow maps obtained by the time-distance heiioseismology analysis of solar-oscillation data from the Helioseismic and Magnetic Imager…

Solar and Stellar Astrophysics · Physics 2022-03-01 Alexander V. Getling , Alexander G. Kosovichev

Solar magnetic activity follows regular cycles of about 11 years with an inversion of polarity in the poles every 22 years. This changing surface magnetism impacts the properties of the acoustic modes. The acoustic mode frequency shifts are…

Solar and Stellar Astrophysics · Physics 2024-11-27 Rafael A. Garcia , Sylvain N. Breton , David Salabert , Sushant C. Tripathy , Kiran Jain , Savita Mathur , Eva Panetier

We analyze and interpret SOHO/MDI data on oscillation frequency changes between 1996 and 2004 focusing on differences between activity minimum and maximum of solar cycle 23. We study only the behavior of the centroid frequencies, which…

Astrophysics · Physics 2009-11-10 W. A. Dziembowski , P. R. Goode

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

Solar radius measurements and their variations -- if any -- are a difficult problem that has vexed researchers for decades. In this paper, we have attempted to clarify the various ways of expressing the definition ''solar diameter'', from a…

Solar and Stellar Astrophysics · Physics 2026-05-25 Jean-Pierre Rozelot , Alexander Kosovichev

We examine the frequency shifts in low-degree helioseismic modes from the Birmingham Solar-Oscillations Network (BiSON) covering the period from 1985 - 2016, and compare them with a number of global activity proxies well as a…

Solar and Stellar Astrophysics · Physics 2017-07-26 R. Howe , G. R. Davies , W. J. Chaplin , Y. Elsworth , S. Basu , S. J. Hale , W. H. Ball , R. W. Komm

Helioseismic data for solar cycles 23 and 24 have shown unequivocally that solar dynamics changes with solar activity. Changes in solar structure have been more difficult to detect. Basu & Mandel (2004) had claimed that the then available…

Solar and Stellar Astrophysics · Physics 2020-11-11 Courtney B. Watson , Sarbani Basu

We have used data collected by the Birmingham Solar-Oscillations Network (BiSON) to perform a helioseismic diagnosis of changes to the Sun's internal structure between four successive solar cycle minima, beginning with the minimum at the…

Solar and Stellar Astrophysics · Physics 2026-02-10 Sarbani Basu , William J. Chaplin , Rachel Howe , Yvonne Elsworth , Steven J. Hale , Eleanor Murray

Frequency and rotational splittings of the solar f-modes are estimated from the GONG data. Contrary to earlier observations the frequencies of f-modes are found to be close to the theoretically computed values for a standard solar model.…

Astrophysics · Physics 2008-11-26 H. M. Antia

The solar cycle onset at mid-latitudes, the slow down of the sunspot drift toward the equator, the tail-like attachment and the overlap of successive cycles at the time of activity minimum are delicate issues in $\alpha\Omega$ dynamo wave…

Solar and Stellar Astrophysics · Physics 2016-09-07 R. Simoniello , S. C. Tripathy , K. Jain , F. Hill

The seismic study of the Sun and other stars offers a unique window into the interior of these stars. Thanks to helioseismology, we know the structure of the Sun to admirable precision. In fact, our knowledge is good enough to use the Sun…

Solar and Stellar Astrophysics · Physics 2016-10-19 Sarbani Basu

Helioseismology has allowed us to infer the rotation in the greater part of the solar interior with high precision and resolution. The results show interesting conflicts with earlier theoretical expectations, indicating that the the Sun is…

Astrophysics · Physics 2007-05-23 J. Christensen-Dalsgaard , M. J. Thompson

Helioseismology has provided very precise information about the solar internal sound speed and density throughout most of the solar interior. The results are generally quite close to the properties of standard solar models. Since the solar…

Astrophysics · Physics 2007-05-23 J. Christensen-Dalsgaard

We show in this paper that the changes of the solar diameter in response to variations of large scale magnetic fields and turbulence are not homologous. For the best current model, the variation at the photospheric level is over 1000 times…

Astrophysics · Physics 2016-08-16 Sabatino Sofia , Sarbani Basu , Pierre Demarque , Linghuai Li , Gerard Thuillier

At subterahertz frequencies -- i.e., millimeter and submillimeter wavelengths -- there is a gap of measurements of the solar radius as well as other parameters of the solar atmosphere. As the observational wavelength changes, the radius…

Solar and Stellar Astrophysics · Physics 2021-04-07 Fabian Menezes , Caius L. Selhorst , Carlos Guillermo Giménez de Castro , Adriana Valio

The goal of local helioseismology is to elicit three-dimensional information about the sub-surface (or far-side) structure and dynamics of the Sun from observations of the helioseismic wave field at the surface. The physical quantities of…

Solar and Stellar Astrophysics · Physics 2015-05-19 Hannah Schunker

Solar activity has significantly changed over the last two Schwabe cycles. After a long and deep minimum at the end of Cycle 23, the weaker activity of Cycle 24 contrasts with the previous cycles. In this work, the response of the solar…

Solar and Stellar Astrophysics · Physics 2015-06-24 D. Salabert , R. A. Garcia , S. Turck-Chieze