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Effects of rotational mode coupling on photometric parameters of stellar oscillations are studied. At moderate rotation rates, a strong coupling between modes of spherical harmonic degree, $\ell$, differing by 2 and of the same azimuthal…

Perturbation theory is used to calculate the frequency shift of acoustic modes of an homogeneous turbulent fluid and the frequency shifts of solar modes due to turbulent convection. For sound waves in a random flow, the fractional frequency…

Astrophysics · Physics 2009-10-30 Andrei V. Gruzinov

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

Recently, it has been reported that a candidate for a quark star may have been observed. In this article, we pay attention to quark stars with radiation radii in the reported range. We calculate nonradial oscillations of $f$-, $w$- and…

General Relativity and Quantum Cosmology · Physics 2009-11-10 Hajime Sotani , Tomohiro Harada

We present an adaptation of the rotation-corrected, m-averaged spectrum technique designed to observe low signal-to-noise-ratio, low-frequency solar p modes. The frequency shift of each of the 2l+1 m spectra of a given (n,l) multiplet is…

Solar and Stellar Astrophysics · Physics 2011-02-11 D. Salabert , J. Leibacher , T. Appourchaux , F. Hill

We study the effects of different descriptions of the solar surface convection on the eigenfrequencies of p-modes. 1-D evolution calculations of the whole Sun and 3-D hydrodynamic and magnetohydrodynamic simulations of the current surface…

Solar and Stellar Astrophysics · Physics 2015-06-17 Laurent Piau , Remo Collet , Robert F. Stein , Regner Trampedach , Pierre Morel , Sylvaine Turck-Chieze

In a previous paper we suggested that, for a given p mode, the excitation function is the same as the component of the solar background noise that has an identical surface spherical harmonic projection (over the corresponding range of…

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

We present the power spectrum of solar irradiance during 1985 and 1987 obtained from the ACRIM project from time scales of minutes to months. At low frequency the spectra are Lorentzian. At higher frequencies they are proportional to…

Astrophysics · Physics 2009-10-28 Jon D. Pelletier

The solar-cyle variation of acoustic mode frequencies has a frequency dependence related to the inverse mode inertia. The discrepancy between model predictions and measured oscillation frequencies for solar and solar-type stellar acoustic…

Solar and Stellar Astrophysics · Physics 2016-12-07 R. Howe , S. Basu , G. R. Davies , W. H. Ball , W. J. Chaplin , Y. Elsworth , R. Komm

Small cyclic variations in the frequencies of acoustic modes are expected to be a common phenomenon in solar-like pulsators, as a result of stellar magnetic activity cycles. The frequency variations observed throughout the solar and stellar…

Solar and Stellar Astrophysics · Physics 2015-06-12 A. R. G. Santos , M. S. Cunha , J. J. G. Lima

Clouds cast shadows on the surface and locally enhance solar irradiance by absorbing and scattering sunlight, resulting in fast and large solar irradiance fluctuations on the surface. Typical spatiotemporal scales and driving mechanisms of…

Atmospheric and Oceanic Physics · Physics 2023-03-09 Wouter Mol , Bart van Stratum , Wouter Knap , Chiel van Heerwaarden

Fossat et al. (2017) recently reported detecting rotational splitting of g modes indirectly via the interaction with p modes observed directly by the GOLF instrument on SOHO. They concluded that the core of the Sun is rotating 3:8 ? 0:1…

Solar and Stellar Astrophysics · Physics 2019-05-29 P. H. Scherrer , D. O. Gough

The solar radiation spectrum is important for renewable energy harvesting, as well as climate and ecological systems analysis. In addition to seasonal/annual and diurnal oscillations, the signal is composed of different frequencies ($f$)…

Geophysics · Physics 2018-11-01 Golan Bel , Mahesh M. Bandi

We solve the problem of propagation and dissipation of Alfvenic turbulence in a model solar atmosphere consisting of a static photosphere and chromosphere, transition region, and open corona and solar wind, using a phenomenological model…

Astrophysics · Physics 2011-02-11 A. Verdini , M. Velli

Magnetic activity changes the gravito-acoustic modes of solar-like stars and in particular their frequencies. There is an angular-degree dependence that is believed to be caused by the non-spherical nature of the magnetic activity in the…

Solar and Stellar Astrophysics · Physics 2019-06-26 F. Perez Hernandez , R. A. Garcia , S. Mathur , A. R. G. Santos , C. Regulo

Aims: We investigate how well modeled solar irradiances agree with measurements from the SORCE satellite, both for total solar irradiance and broken down into spectral regions on timescales of several years. Methods: We use the SATIRE model…

Solar and Stellar Astrophysics · Physics 2015-05-27 Will T. Ball , Yvonne C. Unruh , Natalie A. Krivova , Sami Solanki , Jerald W. Harder

Context. Large-scale equatorial Rossby modes have been observed on the Sun over the last two solar cycles. Aims. We investigate the impact of the time-varying zonal flows on the frequencies of Rossby modes. Methods. A first-order…

Solar and Stellar Astrophysics · Physics 2020-08-05 C. R. Goddard , A. C. Birch , D. Fournier , L. Gizon

Adiabatic oscillation frequencies of stellar models, computed with the standard mixing-length formulation for convection, increasingly deviate with radial order from observations in solar-like stars. Standard solar models overestimate…

Solar and Stellar Astrophysics · Physics 2016-11-15 G. Houdek , R. Trampedach , M. J. Aarslev , J. Christensen-Dalsgaard

Despite the strong evidence that the peaks in the spectrum of solar oscillations are asymmetric, most determinations of mode frequencies have been based on fits of symmetric Lorentzian profiles to the Fourier or power spectra of oscillation…

We consider the time-frequency analysis of a scattered light curve of a directly imaged exoplanet. We show that the geometric effect due to planetary obliquity and orbital inclination induce the frequency modulation of the apparent diurnal…

Instrumentation and Methods for Astrophysics · Physics 2020-04-20 Hajime Kawahara
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