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Many helioseismic measurements suffer from substantial systematic errors. A particularly frustrating one is that time-distance measurements suffer from a large center to limb effect which looks very similar to the finite light travel time,…

Solar and Stellar Astrophysics · Physics 2015-06-11 Charles S. Baldner , Jesper Schou

Granulation in the photospheres of FGK-type stars induces variability in absorption lines, complicating exoplanet detection via radial velocities and characterisation via transmission spectroscopy. We aim to quantify the impact of…

Birmingham Solar Oscillations Network (BiSON) instruments use resonant scattering spectrometers to make unresolved Doppler velocity observations of the Sun. Unresolved measurements are not homogenous across the solar disc and so the…

Solar and Stellar Astrophysics · Physics 2015-05-13 A. M. Broomhall , W. J. Chaplin , Y. Elsworth , R. New

In the solar convection zone acoustic waves are scattered by turbulent sound speed fluctuations. In this paper the scattering of waves by convective cells is treated using Rytov's technique. Particular care is taken to include diffraction…

Astrophysics · Physics 2009-10-31 M. Brüggen

Treatments of the radio scattering due to density turbulence in the solar wind typically employ asymptotic approximations to the phase structure function. We use a general structure function (GSF) that straddles the asymptotic limits and…

Solar and Stellar Astrophysics · Physics 2015-09-28 Madhusudan Ingale

The solar brightness varies on timescales from minutes to decades. Determining the sources of such variations, often referred to as solar noise, is of importance for multiple reasons: a) it is the background that limits the detection of…

Solar and Stellar Astrophysics · Physics 2017-11-28 A. I. Shapiro , S. K. Solanki , N. A. Krivova , R. H. Cameron , K. L. Yeo , W. K. Schmutz

Large-scale plasma flows in the Sun's convection zone likely play a major role in solar dynamics on decadal timescales. In particular, quantifying meridional motions is a critical ingredient for understanding the solar cycle and the…

Solar and Stellar Astrophysics · Physics 2015-06-19 Shukur Kholikov , Alexander Serebryanskiy , Jason Jackiewicz

Using data from the Global Oscillations Network Group (GONG) that covers the period from 1995 to 1998 we study the change in frequencies of solar oscillations with solar activity. From these frequencies we attempt to determine any possible…

Astrophysics · Physics 2015-06-24 Sarbani Basu , H. M. Antia

The solar tachocline at the bottom of the convection zone is an important region for the dynamics of the Sun and the solar dynamo. In this region, the sound speed inferred by global helioseismology exhibits a bump of approximately 0.4%…

Solar and Stellar Astrophysics · Physics 2009-09-28 Junwei Zhao , Thomas Hartlep , A. G. Kosovichev , N. N. Mansour

On the one hand, several types of global-scale inertial modes of oscillation have been observed on the Sun. They include the equatorial Rossby modes, critical-latitude modes, and high-latitude modes. On the other hand, the columnar…

Solar and Stellar Astrophysics · Physics 2022-06-08 Yuto Bekki , Robert H. Cameron , Laurent Gizon

We present a detailed comparison between simulations and seeing-free observations that takes into account the crucial influence of instrumental image degradation. We use images of quiet Sun granulation taken in the blue, green and red…

Solar and Stellar Astrophysics · Physics 2015-05-13 Sven Wedemeyer-Böhm , Luc Rouppe van der Voort

Due to non-homogeneous mass distribution and non-uniform velocity rate inside the Sun, the solar outer shape is distorted in latitude. In this paper, we analyze the consequences of a temporal change in this figure on the luminosity. To do…

Solar and Stellar Astrophysics · Physics 2011-08-31 Z. Fazel , J. P. Rozelot , S. Lefebvre , A. Ajabshirizadeh , S. Pireaux

Stellar activity and, in particular, convection-related surface structures, potentially cause fluctuations that can affect the transit light curves. Surface convection simulations can help the interpretation of ToV. We used realistic…

Earth and Planetary Astrophysics · Physics 2015-03-18 A. Chiavassa , C. Pere , M. Faurobert , G. Ricort , P. Tanga , Z. Magic , R. Collet , M. Asplund

Context: The cross-covariance of solar oscillations observed at pairs of points on the solar surface is a fundamental ingredient in time-distance helioseismology. Wave travel times are extracted from the cross-covariance function and are…

Solar and Stellar Astrophysics · Physics 2016-09-14 Kaori Nagashima , Takashi Sekii , Laurent Gizon , Aaron C. Birch

The nature of turbulence in molecular clouds is one of the key parameters that control star formation efficiency: compressive motions, as opposed to solenoidal motions, can trigger the collapse of cores, or mark the expansion of Hii…

The solar abundances have undergone a major downward revision in the last decade, reputedly as a result of employing 3D hydrodynamical simulations to model the inhomogeneous structure of the solar photosphere. The very low oxygen abundance…

Solar and Stellar Astrophysics · Physics 2009-10-27 E. Caffau , H. -G. Ludwig , M. Steffen

The overall framework for the study of solar convection and oscillations is the spherically symmetric component of solar structure. I discuss those properties of the solar interior which depend on convection and other possible…

Astrophysics · Physics 2016-01-27 J. Christensen-Dalsgaard

Local-box hydrodynamical model atmospheres provide statistical information about a star's emergent radiation field which allows one to predict the level of its granulation-related micro-variability. Space-based photometry is now…

Solar and Stellar Astrophysics · Physics 2015-05-13 H. -G. Ludwig , R. Samadi , M. Steffen , T. Appourchaux , F. Baudin , K. Belkacem , P. Boumier , M. -J. Goupil , E. Michel

Rossby waves play an important role in mediating the angular momentum of rotating spherical fluids, creating weather on Earth and tuning exoplanet orbits in distant stellar systems (Ogilvie 2014). Their recent discovery in the solar…

Solar and Stellar Astrophysics · Physics 2020-03-18 Krishnendu Mandal , Shravan Hanasoge

Optical aberrations and instrument resolution can affect the observed morphological properties of features in the solar atmosphere. However, little work has been done to study the effects of spatial resolution on the dynamical processes…

Solar and Stellar Astrophysics · Physics 2026-01-06 M. Berretti , M. Stangalini , D. B. Jess , S. Jafarzadeh , S. D. T. Grant , G. Verth , V. Fedun , G. Chambers , F. Berrilli
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