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We investigate the effect of localized opacity modifications on the sound-speed profile of solar models. The sound-speed difference between the Sun and a solar model is used to deduce the opacity correction that would be required to bring…

Astrophysics · Physics 2008-02-03 S. C. Tripathy , Sarbani Basu , J. Christensen-Dalsgaard

Using the oscillation frequencies of alpha Cen A recently discovered by Bouchy & Carrier, the available astrometric, photometric and spectroscopic data, we tried to improve the calibration of the visual binary system alpha Cen. With the…

Astrophysics · Physics 2016-08-30 F. Thevenin , J. Provost , P. Morel , G. Berthomieu , F. Bouchy , F. Carrier

The questions whether the Sun shrinks with the solar activity and what causes this have been a subject of debate. Helioseismology provides means to measure with high precision the radial displacement of subsurface layers, co-called "seismic…

Solar and Stellar Astrophysics · Physics 2018-07-25 Alexander Kosovichev , Jean-Pierre Rozelot

We find that the mean meridional motion of the spot groups varies considerably on a time scale of about 5-20 years. The maximum amplitude of the variation is about 10-15 m/s in both the Sun's northern and the southern hemispheres. Variation…

Solar and Stellar Astrophysics · Physics 2009-11-26 J. Javaraiah

The solar activity in the current, that is, the 24-th, sunspot cycle is analyzed. Cyclic variations in the sunspot number (SSN) and radiation fluxes in various spectral ranges have been estimated in comparison with the general level of the…

Solar and Stellar Astrophysics · Physics 2018-05-01 E. A. Bruevich , V. V. Bruevich , G. V. Yakunina

The energy balance for an atmospheric layer near the soil is evaluated. By integrating it over the whole day period a linear relationship between the global daily solar radiation incident on a horizontal surface and the product of the…

Atmospheric and Oceanic Physics · Physics 2014-01-31 Antonio Dumas , Andrea Andrisani , Maurizio Bonnici , Mauro Madonia , Michele Trancossi

The Solar Diameter Monitor measured the duration of solar meridian transits during the 6 years 1981 to 1987, spanning the declining half of solar cycle 21. We have combined these photoelectric measurements with models of the solar…

Astrophysics · Physics 2008-11-26 T. M. Brown , J. Christensen-Dalsgaard

The estimate of the change rate of the solar gravitational parameter $\mathrm{d}(GM_{\odot})/\mathrm{d}t$ is obtained from processing modern positional observations of planets and spacecraft. Observations were processed and parameters were…

Earth and Planetary Astrophysics · Physics 2022-01-25 E. V. Pitjeva , N. P. Pitjev , D. A. Pavlov , C. C. Turygin

Stellar seismology appears more and more as a powerful tool for a better determination of the fundamental properties of solar-type stars. However the particular case of Sun is still challenging. The helioseismic sound speed determination…

Long-term variations of solar differential rotation and sunspot activity are investigated through re-analyzing the data on parameters of the differential rotation law obtained by Makarov, Tlatov, and Callebaut (1997), Javaraiah, Bertello,…

Solar and Stellar Astrophysics · Physics 2015-06-05 K. J. Li , W. Feng , X. J. Shi , J. L. Xie , P. X. Gao , H. F. Liang

Measurements of the radius and limb brightening of the Sun provide important information about the solar atmosphere structure and temperature. The solar radius increases as the observation at radio frequency decreases, indicating that each…

Solar and Stellar Astrophysics · Physics 2021-12-15 Fabian Menezes , Caius L. Selhorst , Carlos Guillermo Giménez de Castro , Adriana Valio

There are claims that there is correlation between the speed of center of mass of the solar system and the global temperature anomaly. This is partly grounded in data analysis and partly in a priori expectations. The magnitude squared…

Earth and Planetary Astrophysics · Physics 2015-05-19 Sverre Holm

A simple solar scaling relation for estimating the ages of main-sequence stars from asteroseismic and spectroscopic data is developed. New seismic scaling relations for estimating mass and radius are presented as well, including a purely…

Solar and Stellar Astrophysics · Physics 2019-05-07 Earl Patrick Bellinger

The Sun is the most studied and well-known star, and as such, solar fundamental parameters are often used to bridge gaps in the knowledge of other stars, when these are required for modelling. However, the two most powerful and precise…

Solar and Stellar Astrophysics · Physics 2020-10-06 Diogo Capelo , Ilídio Lopes

The observed frequency shifts of the high-degree solar fundamental mode are explained using a simple geometrical optics approximation. The predicted fractional frequency shift is proportional to the mean squared velocity of the convection…

Astrophysics · Physics 2007-05-23 Andrei Gruzinov

Using the recently obtained GONG frequencies, we investigate the properties of the solar interior by constructing solar models with various input physics like opacities, equation of state, nuclear reaction rates etc. The differential…

Astrophysics · Physics 2007-05-23 S. C. Tripathy , H. M. Antia , F. Hill , A. Ambastha

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

A new set of accurately measured frequencies of solar oscillations are used to infer the rotation rate inside the Sun, as a function of radial distance as well as latitude. We have adopted a regularized least squares technique with…

Astrophysics · Physics 2009-10-30 H. M. Antia , Sarbani Basu , S. M. Chitre

Analysis of f-mode frequencies has provided a measure of the radius of the Sun which is lower, by a few hundredths per cent, than the photospheric radius determined by direct optical measurement. Part of this difference can be understood by…

Solar and Stellar Astrophysics · Physics 2023-10-18 M. Takata , D. O. Gough

We construct updated solar models with different sets of solar abundances, including the most recent determinations by Asplund et al. (2009). The latter work predicts a larger ($\sim 10%$) solar metallicity compared to previous measurements…

Solar and Stellar Astrophysics · Physics 2011-03-31 Aldo Serenelli , Sarbani Basu , Jason W. Ferguson , Martin Asplund
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