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When inverting solar spectra, image degradation effects that are present in the data are usually approximated or not considered. We develop a data reduction method that takes these issues into account and minimizes the resulting errors. By…

Instrumentation and Methods for Astrophysics · Physics 2015-06-11 M. van Noort

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

Determination of the coronal electron density by the inversion of white-light polarized brightness (pB) measurements by coronagraphs is a classic problem in solar physics. An inversion technique based on the spherically symmetric geometry…

Solar and Stellar Astrophysics · Physics 2014-06-30 Tongjiang Wang , Joseph M. Davila

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

Stochastic Bilevel optimization usually involves minimizing an upper-level (UL) function that is dependent on the arg-min of a strongly-convex lower-level (LL) function. Several algorithms utilize Neumann series to approximate certain…

Optimization and Control · Mathematics 2023-06-22 Xuxing Chen , Tesi Xiao , Krishnakumar Balasubramanian

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

We describe two inversion methods for the reconstruction of hard X-ray solar images. The methods are tested against experimental visibilities recorded by the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) and synthetic…

Solar and Stellar Astrophysics · Physics 2019-07-17 Anna Maria Massone , Federica Sciacchitano , Michele Piana , Alberto Sorrentino

Thanks to their high quality, new and upcoming asteroseismic observations - with CoRoT, Kepler, and from the ground... - can benefit from the experience gained with helioseismology. We focus in this paper on solar-like oscillations, for…

Astrophysics · Physics 2008-04-02 J. Ballot , T. Appourchaux , T. Toutain , M. Guittet

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

The main aim of this work is to determine the solar differential rotation by tracing sunspot groups during the period 1964-2016, using the Kanzelh\"ohe Observatory for Solar and Environmental Research (KSO) sunspot drawings and white light…

Solar wind conditions are predominantly predicted via three-dimensional numerical magnetohydrodynamic (MHD) models. Despite their ability to produce highly accurate predictions, MHD models require computationally intensive high-dimensional…

Computational Physics · Physics 2022-11-30 Opal Issan , Boris Kramer

The advent of space-based photometry missions in the early 21st century enabled the application to asteroseismic data of advanced inference techniques until then restricted to the field of helioseismology. The high quality of the…

Solar and Stellar Astrophysics · Physics 2022-06-24 Gaël Buldgen , Jérôme Bétrisey , Ian W. Roxburgh , Sergei V. Vorontsov , Daniel R. Reese

Solar rotational tomography (SRT) applied to white-light coronal images observed at multiple aspect angles has been the preferred approach for determining the three-dimensional (3D) electron density structure of the solar corona. However,…

Solar and Stellar Astrophysics · Physics 2016-10-04 Didier Vibert , Christelle Peillon , Philippe Lamy , Richard A. Frazin , Julien Wojak

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

Local helioseismology comprises of imaging and inversion techniques employed to reconstruct the dynamic and interior of the Sun from correlations of oscillations observed on the surface, all of which require modeling solar oscillations and…

Solar and Stellar Astrophysics · Physics 2025-12-01 Ha Pham , Florian Faucher , Damien Fournier , Hélène Barucq , Laurent Gizon

Gravity-mode asteroseismology has significantly improved our understanding of mixing in intermediate mass stars. However, theoretical pulsation periods of stellar models remain in tension with observations, and it is often unclear how the…

Solar and Stellar Astrophysics · Physics 2023-06-28 Vincent Vanlaer , Conny Aerts , Earl P. Bellinger , Jørgen Christensen-Dalsgaard

In the past few years, the CoRoT and Kepler missions have carried out what is now called the space photometry revolution. This revolution is still ongoing thanks to K2 and will be continued by the Tess and Plato2.0 missions. However, the…

Solar and Stellar Astrophysics · Physics 2017-11-08 Gaël Buldgen , Daniel Reese , Marc-Antoine Dupret

Meridional flow is thought to play a very important role in the dynamics of the solar convection zone; however, because of its relatively small amplitude, precisely measuring it poses a significant challenge. Here we present a complete…

Solar and Stellar Astrophysics · Physics 2015-06-02 J. Jackiewicz , A. Serebryanskiy , S. Kholikov

High-resolution representation is necessary for human pose estimation to achieve high performance, and the ensuing problem is high computational complexity. In particular, predominant pose estimation methods estimate human joints by 2D…

Computer Vision and Pattern Recognition · Computer Science 2023-10-13 Yixuan Zhou , Xuanhan Wang , Xing Xu , Lei Zhao , Jingkuan Song

Using a 3D global solver of the linearized Euler equations, we model acoustic oscillations over background velocity flow fields of single-cell meridional circulation with deep and shallow return flows as well as double-cell meridional…

Solar and Stellar Astrophysics · Physics 2022-02-15 Andrey M. Stejko , Alexander G. Kosovichev , Valery V. Pipin