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Magnetohydrodynamic (MHD) wave activity is ubiquitous in the solar atmosphere. MHD seismology aims to determine difficult to measure physical parameters in solar atmospheric magnetic and plasma structures by a combination of observed and…

Solar and Stellar Astrophysics · Physics 2015-06-04 Inigo Arregui

Linear theory is a well developed framework for characterizing instabilities in weakly collisional plasmas, such as the solar wind. In the previous instalment of this series, we analyzed ~1.5M proton and alpha particle Velocity Distribution…

Solar and Stellar Astrophysics · Physics 2023-07-26 Mihailo M. Martinovic , Kristopher G. Klein

Being able to image active regions on the Sun's far side is useful for modeling the global-scale magnetic field around the Sun, and for predicting the arrival of major active regions that rotate around the limb onto the near side.…

Solar and Stellar Astrophysics · Physics 2020-01-08 Junwei Zhao , Dominick Hing , Ruizhu Chen , Shea Hess Webber

We show that the motions of supergranules are consistent with a model in which they are simply advected by the axisymmetric flows in the Sun's surface shear layer. We produce a 10-day series of simulated Doppler images at a 15-minute…

Solar and Stellar Astrophysics · Physics 2015-05-19 David H. Hathaway , Peter E. Williams , Kevin Dela Rosa , Manfred Cuntz

Aims: Our goal is to develop methodologies to seamlessly track transient solar wind flows viewed by coronagraphs or heliospheric imagers from rapidly varying viewpoints. Methods: We constructed maps of intensity versus time and elongation…

Solar and Stellar Astrophysics · Physics 2021-06-02 A. Nindos , S. Patsourakos , A. Vourlidas , P. C. Liewer , P. Penteado , J. R. Hall

Helioseismology is the branch of the Solar Physics which studies the solar global oscillations, a phenomenon very important in order to understand the inside of the Sun. We explain here a method for measuring the solar velocity fields along…

Astrophysics · Physics 2007-05-23 I. Formicola , A. Longobardo , C. Pinto , P. Cerulo

We review recent advances concerning helioseismology, solar models and solar neutrinos. Particularly we shall address the following points: i) helioseismic tests of recent SSMs; ii)the accuracy of the helioseismic determination of the sound…

Astrophysics · Physics 2014-10-13 G. Fiorentini , B. Ricci

Context: The interaction of plasma motions and magnetic fields is an important mechanism, which drives solar activity in all its facets. For example, photospheric flows are responsible for the advection of magnetic flux, the redistribution…

Solar and Stellar Astrophysics · Physics 2015-05-27 M. Verma , C. Denker

Context. The spatial power spectrum of supergranulation does not fully characterize the underlying physics of turbulent convection. For example, it does not describe the non-Gaussianity in the horizontal flow divergence. Aims. Our aim is to…

Solar and Stellar Astrophysics · Physics 2020-04-01 Vincent G. A. Böning , Aaron C. Birch , Laurent Gizon , Thomas L. Duvall , Jesper Schou

Understanding the governing mechanism of solar magnetism remains an outstanding challenge in astrophysics. Seismology is the most compelling technique with which to infer the internal properties of the Sun and stars. Waves in the Sun,…

Solar and Stellar Astrophysics · Physics 2017-07-31 Shravan M. Hanasoge

In its first encounter at solar distances as close as r = 0.16AU, Parker Solar Probe (PSP) observed numerous local reversals, or inversions, in the heliospheric magnetic field (HMF), which were accompanied by large spikes in solar wind…

Solar and Stellar Astrophysics · Physics 2021-01-06 Allan R Macneil , Mathew J Owens , Robert T Wicks , Mike Lockwood

We invert for motions at the surface of Earth's core under spatial and temporal constraints that depart from the mathematical smoothings usually employed to ensure spectral convergence of the flow solutions. Our spatial constraints are…

Geophysics · Physics 2023-12-18 Olivier Barrois , Nicolas Gillet , Julien Aubert

The solar photosphere is the visible surface of the Sun, where many bright granules, surrounded by narrow dark intergranular lanes, are observed everywhere. The granular pattern is a manifestation of convective motion at the photospheric…

Solar and Stellar Astrophysics · Physics 2017-02-15 T. Oba , Y. Iida , T. Shimizu

Near-surface flows measured by the ring-diagram technique of local helioseismology show structures that persist over multiple rotations. We examine these phenomena using data from the {\em Global Oscillation Network Group} (GONG) and the…

Solar and Stellar Astrophysics · Physics 2015-08-19 R. Howe , R. W. Komm , D. Baker , L. Harra , L. van Driel-Gesztelyi , R. S. Bogart

We suggest a method that evaluates the horizontal velocity in the solar photosphere with easily observable values using a combination of neural network and radiative magnetohydrodynamics simulations. All three-component velocities of…

Solar and Stellar Astrophysics · Physics 2023-09-06 Hiroyuki Masaki , Hideyuki Hotta , Yukio Katsukawa , Ryohtaroh T. Ishikawa

The observed solar photospheric magnetic fields and Doppler velocities are frequently used to quantify the Poynting flux and helicity flux. Multiple methods have been developed for this purpose, but their estimates of the Poynting flux and…

Solar and Stellar Astrophysics · Physics 2026-04-20 Jiayi Liu , Xudong Sun , Peter W. Schuck , Lars K. S. Daldorff

We present a quantitative estimate of the accuracy of the calculated diffusion coefficients, by comparing predictions of solar models with observational data provided by helioseismology. By taking into account the major uncertainties in…

Astrophysics · Physics 2011-01-04 G. Fiorentini , M. Lissia , B. Ricci

Scintillometer measurements allow for estimations of the refractive index structure parameter $C_n^2$ over large areas in the atmospheric surface layer. Turbulent fluxes of heat and momentum are inferred through coupled sets of equations…

Atmospheric and Oceanic Physics · Physics 2014-09-01 Matthew A. Gruber , Gilberto J. Fochesatto , Oscar K. Hartogensis , Martin Lysy

Solar torsional oscillations are migrating bands of slower- and faster-than-average rotation, which are strongly related to the Sun's magnetic cycle. We perform a long-term study (16 yr) of hemispherical asymmetry in solar torsional…

Solar and Stellar Astrophysics · Physics 2018-08-01 Lekshmi B , Dibyendu Nandy , H M Antia

In this paper, we aim to perform sensitivity analysis of set-valued models and, in particular, to quantify the impact of uncertain inputs on feasible sets, which are key elements in solving a robust optimization problem under constraints.…

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