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The Sun is the most studied of all stars. It is a reference for all other observed stars and a laboratory of fundamental physics helping us understand processes occuring in conditions irreproducible on Earth. However, our understanding of…

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

Oscillations detected on the solar surface provide a unique possibility for investigations of the interior properties of a star. Through major observational efforts, including extensive observations from space, as well as development of…

Astrophysics · Physics 2008-11-26 J. Christensen-Dalsgaard

The Helioseismic and Magnetic Imager (HMI) has just started producing data that will help determine what the sources and mechanisms of variability in the Sun's interior are. The instrument measures the Doppler shift and the polarization of…

Solar and Stellar Astrophysics · Physics 2010-12-20 Rebecca Centeno , Steve Tomczyk , Juan Manuel Borrero , Sebastien Couvidat , Keiji Hayashi , Todd Hoeksema , Yang Liu , Jesper Schou

Normal modes are coupled by the presence of perturbations in the Sun, providing a novel and under-appreciated helioseismic technique with which to image the solar interior. The process of measuring coupling between normal modes is…

Solar and Stellar Astrophysics · Physics 2018-07-18 Shravan Hanasoge

The richness and very high accuracy of the observed frequencies of solar oscillations provide tight constraints on the structure of the solar interior and hence on the assumptions underlying the calculation of solar models. This permits the…

Astrophysics · Physics 2007-05-23 J. Christensen-Dalsgaard

The dynamics of the solar radiative interior are still poorly constrained by comparison to the convective zone. This disparity is even more marked when we attempt to derive meaningful temporal variations. Many data sets contain a small…

Solar and Stellar Astrophysics · Physics 2015-06-05 Antonio Eff-Darwich , Sylain G. Korzennik

In helioseismic studies, an observational parameter of primary concern is the P-angle, the angle along which lies the solar axis of rotation for a given image. For the six observing sites employed by The Global Oscillation Network Group…

Solar and Stellar Astrophysics · Physics 2023-04-17 Anna L. H. Hughes , Irene Gonzalez-Hernandez , Sean G. McManus , Kiran Jain , Sushanta C. Tripathy

We present a new approach to study the properties of the sun. We consider small variations of the physical and chemical properties of the sun with respect to Standard Solar Model predictions and we linearize the structure equations to…

Solar and Stellar Astrophysics · Physics 2014-11-20 F. L. Villante , B. Ricci

Asteroseismology has emerged as the best way to characterize the global and internal properties of nearby stars. Often, this characterization is achieved by fitting stellar evolution models to asteroseismic observations. The star under…

Solar and Stellar Astrophysics · Physics 2020-12-25 Earl P. Bellinger , Sarbani Basu , Saskia Hekker

Inferring interior properties of the Sun from photospheric measurements of the seismic wavefield constitutes the helioseismic inverse problem. Deviations in seismic measurements (such as wave travel times) from their fiducial values…

Solar and Stellar Astrophysics · Physics 2015-06-18 Shravan Hanasoge , Jeroen Tromp

Time-distance helioseismology is a set of powerful tools to study features below the Sun's surface. Inverse methods are needed to interpret time-distance measurements, with many examples in the literature. However, techniques that utilize a…

Solar and Stellar Astrophysics · Physics 2020-10-14 Jason Jackiewicz

Normal-mode helioseismic data analysis uses observed solar oscillation spectra to infer perturbations in the solar interior due to global and local-scale flows and structural asphericity. Differential rotation, the dominant global-scale…

Solar and Stellar Astrophysics · Physics 2021-03-30 Samarth G. Kashyap , Srijan Bharati Das , Shravan M. Hanasoge , Martin F. Woodard , Jeroen Tromp

Helioseismic techniques such as ring-diagram analysis have often been used to determine the subsurface structural differences between solar active and quiet regions. Results obtained by inverting the frequency differences between the…

Astrophysics · Physics 2009-11-13 Chia-Hsien Lin , Sarbani Basu , Linghuai Li

Measuring the temperature structure of the solar atmosphere is critical to understanding how it is heated to high temperatures. Unfortunately, the temperature of the upper atmosphere cannot be observed directly, but must be inferred from…

Solar and Stellar Astrophysics · Physics 2017-03-08 Harry P. Warren , Jeff M. Byers , Nicholas A. Crump

We present an automated procedure that derives simultaneously the effective temperature $T_{eff}$, the surface gravity logg, the metallicity [Fe/H], and the equatorial projected rotational velocity vsini for "normal" A and Am stars. The…

Instrumentation and Methods for Astrophysics · Physics 2016-04-20 M. Gebran , W. Farah , F. Paletou , R. Monier , V. Watson

Predictions from science and engineering models depend on the values of the model's input parameters. As the number of parameters increases, algorithmic parameter studies like optimization or uncertainty quantification require many more…

Numerical Analysis · Mathematics 2015-10-16 Paul G. Constantine , Brian Zaharatos , Mark Campanelli

This paper examines a number of analytic models which can describe the gravitationally stabilized fusion reactor of the Sun. An analytical multiparameter model is shown to reproduce various structure parameters such as density, mass,…

Classical Analysis and ODEs · Mathematics 2016-09-06 Hans J. Haubold , Arak Mathai Mathai

The Ca II H line is one of the strongest lines in the solar spectrum and provides continuous information on the solar atmosphere from the photosphere to the lower chromosphere. We describe an inversion approach that reproduces observed Ca…

Solar and Stellar Astrophysics · Physics 2013-03-14 C. Beck , R. Rezaei , K. G. Puschmann

We describe a global parametric model for the observed power spectra of solar oscillations of intermediate and low degree. A physically motivated parameterization is used as a substitute for a direct description of mode excitation and…

Solar and Stellar Astrophysics · Physics 2015-06-17 Sergei V. Vorontsov , Stuart M. Jefferies