English
Related papers

Related papers: Solar oblateness & asphericities temporal variatio…

200 papers

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

In helioseismology, there is a well-known offset between observed and computed oscillation frequencies. This offset is known to arise from improper modeling of the near-surface layers of the Sun, and a similar effect must occur for models…

Astrophysics · Physics 2009-11-13 Hans Kjeldsen , Timothy R. Bedding , Joergen Christensen-Dalsgaard

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

In this article, we report an evidence of very high and statistically significant relationship between hemispheric asymmetry in solar coronal rotation rate and solar activity. Our approach is based on cross correlation of hemispheric…

Solar and Stellar Astrophysics · Physics 2020-10-28 Jaidev Sharma , Anil K Malik , Brajesh Kumar , Hari Om Vats

The variability of the spectral solar irradiance (SSI) over the course of the 11-year solar cycle is one of the manifestations of solar magnetic activity. There is a strong evidence that the SSI variability has an effect on the Earth's…

Solar and Stellar Astrophysics · Physics 2020-04-29 Anna V. Shapiro , Alexander I. Shapiro , Laurent Gizon , Natalie A. Krivova , Sami K. Solanki

Helioseismology has provided very detailed information about the solar interior, and extensive data on a large number of stars, although at less detail, are promised by the ongoing and upcoming asteroseismic projects. In the solar case…

Solar and Stellar Astrophysics · Physics 2015-05-19 J. Christensen-Dalsgaard

The recent discovery of inertial waves on the surface of the Sun offers new possibilities to learn about the solar interior. These waves are long-lived with a period on the order of the Sun rotation period ($\sim$27 days) and are sensitive…

Solar and Stellar Astrophysics · Physics 2024-03-25 Tram Thi Ngoc Nguyen , Thorsten Hohage , Damien Fournier , Laurent Gizon

Recent revisions of the determination of the solar composition have resulted in solar models in marked disagreement with helioseismic inferences. The effect of the composition change on the model is largely caused by the change in the…

Local helioseismology has opened new frontiers in our quest for understanding of the internal dynamics and dynamo on the Sun. Local helioseismology reconstructs subsurface structures and flows by extracting coherent signals of acoustic…

Solar and Stellar Astrophysics · Physics 2016-07-20 Alexander G. Kosovichev , Junwei Zhao

By combining ground-based spectrographic observations of variability in the chromospheric emission from Sun-like stars with the variability seen in their eigenmode frequencies, it is possible to relate the changes observed at the surfaces…

Solar and Stellar Astrophysics · Physics 2019-03-27 C. Karoff , T. S. Metcalfe , B. T. Montet , N. E. Jannsen , A. R. G. Santos , M. B. Nielsen , W. J. Chaplin

Inaccurate modelling of the near-surface layers of solar models causes a systematic difference between modelled and observed solar mode frequencies. This difference---known as the "surface effect" or "surface term"---presumably also exists…

Solar and Stellar Astrophysics · Physics 2017-11-07 Warrick H. Ball

Precise, high-cadence, long-term records of stellar spectral variability at different temporal scales lead to better understanding of a wide variety of phenomena including stellar atmospheres and dynamos, convective motions, and rotational…

Solar and Stellar Astrophysics · Physics 2023-07-19 Serena Criscuoli , Sergey Marchenko , Matthew DeLand , Debi Choudhary , Greg Kopp

We seek to address whether solar-cycle frequency shifts of the Sun's low-l p modes `distort' the underlying shapes of the mode peaks, when those peaks are observed in power frequency spectra made from data spanning large fractions, or more,…

Astrophysics · Physics 2009-11-13 W. J. Chaplin , Y. Elsworth , R. New , T. Toutain

Several works have reported changes of the Sun's subsurface stratification inferred from f-mode or p-mode observations. Recently a non-homologous variation of the subsurface layers with depth and time has been deduced from f-modes. Progress…

Astrophysics · Physics 2011-02-11 Sandrine Lefebvre , Phu Anh Phi Nghiem , Sylvaine Turck-Chieze

We use the technique of wavelet analysis to quantitatively investigate the role of solar variability in forcing terrestrial climate change on solar cycle timescales (roughly 11 years). We examine the connection between mean annual solar…

Astrophysics · Physics 2007-05-23 Matthew J. Lewis , Katherine Freese

Regular spaceborne measurements have revealed that solar brightness varies on multiple timescales, variations on timescales greater than a day being attributed to surface magnetic field. Independently, ground-based and spaceborne…

Solar and Stellar Astrophysics · Physics 2016-04-27 A. I. Shapiro , S. K. Solanki , N. A. Krivova , K. L. Yeo , W. K. Schmutz

The origin of the quiet Sun magnetism is under debate. Investigating the solar cycle variation observationally in more detail can give us clues about how to resolve the controversies. We investigate the solar cycle variation of the most…

Solar and Stellar Astrophysics · Physics 2022-09-21 Maarit J. Korpi-Lagg , Andreas Korpi-Lagg , Nigul Olspert , Hong-Linh Truong

Surface solar irradiance varies on scales as small as seconds or meters due to scattering and absorption by the atmosphere. Clouds are the main driver of this variability, but moisture structures in the atmospheric boundary layer and…

Atmospheric and Oceanic Physics · Physics 2024-04-08 Wouter Mol , Bert Heusinkveld , Mary Rose Mangan , Oscar Hartogensis , Menno Veerman , Chiel van Heerwaarden

In recent years solar oscillations have been studied in great detail, both observationally and theoretically; so, perhaps, the Sun currently is the best understood pulsating star. The observational studies include long, almost uninterrupted…

Solar and Stellar Astrophysics · Physics 2010-02-01 A. G. Kosovichev

From the observing campaigns of a number of helioseismic telescope networks such as the Global Oscillation Network Group (GONG) and also from the Solar Heliospheric Observatory satellite (SoHO), helioseismologists now have data on in excess…

Astrophysics · Physics 2007-05-23 Frank P. Pijpers