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When the polarimetric sensitivity and the angular resolution exceed a threshold, magnetic fields show up almost everywhere on the solar surface. Here I revise the observational properties of the weakest polarization signals, which appear in…

Astrophysics · Physics 2007-05-23 J. Sanchez Almeida

Given its unchallenged capabilities in terms of sensitivity and spatial resolution, the combination of imaging spectropolarimetry and numeric Stokes inversion represents the dominant technique currently used to remotely sense the physical…

Instrumentation and Methods for Astrophysics · Physics 2019-11-05 Francisco A. Iglesias , Alex Feller

Helioseismology has produced unprecedented measurements of the Sun's internal structure and dynamics over the past 25 years. Much of this work has been based on global helioseismology. Now local helioseismology too is showing its great…

Solar and Stellar Astrophysics · Physics 2010-03-23 M. J. Thompson

As the global magnetic field of the Sun has an activity cycle, one expects to observe some variation of the dynamical properties of the flows visible in the photosphere. We investigate the flow field during the solar cycle by analysing…

Solar and Stellar Astrophysics · Physics 2017-02-15 Th. Roudier , J. M. Malherbe , G. M. Mirouh

Magnetic helicity is an invariant of ideal magnetohydrodynamics (MHD) that encodes information on the topology of magnetic field lines. It has long been appreciated that magnetic topology is an important constraint for the evolution of…

Solar and Stellar Astrophysics · Physics 2020-09-25 David MacTaggart , Chris Prior

Generation and diffusion of the magnetic field on the Sun is a key mechanism responsible for solar activity on all spatial and temporal scales - from the solar cycle down to the evolution of small-scale magnetic elements in the quiet Sun.…

Solar and Stellar Astrophysics · Physics 2011-12-14 V. I. Abramenko , V. B. Yurchyshyn , P. R. Goode

We obtain information about the magnetic flux present in the quiet Sun by comparing radiative MHD simulations with Hinode/SP observations, with particular emphasis on the role of surface dynamo action. Simulation runs with different…

Solar and Stellar Astrophysics · Physics 2015-05-14 S. Danilovic , M. Schuessler , S. K. Solanki

Studying the emergence of magnetic fields is essential for understanding the physical mechanisms behind various phenomena in the solar atmosphere. Most importantly, the emerging fields offer valuable insights into how energy and mass are…

Solar and Stellar Astrophysics · Physics 2025-08-28 Milan Gošić , Viggo H. Hansteen , Alberto Sainz Dalda , Bart De Pontieu , Luc H. M. Rouppe van der Voort

Solar inter-network magnetic field is the weakest component of solar magnetism, but contributes most of the solar surface magnetic flux. The study on its origin has been constrained by the inadequate tempo-spatial resolution and sensitivity…

Solar and Stellar Astrophysics · Physics 2015-05-26 Chunlan Jin , Jingxiu Wang

A precise knowledge of the surface structure of sunspots is essential to construct adequate input models for helioseismic inversion tools. We summarize our recent findings about the velocity and magnetic field in and around sunspots using…

Solar and Stellar Astrophysics · Physics 2015-03-13 Morten Franz

The theory of multidimensional persistent homology was initially developed in the discrete setting, and involved the study of simplicial complexes filtered through an ordering of the simplices. Later, stability properties of…

Computational Geometry · Computer Science 2013-03-28 Niccolò Cavazza , Marc Ethier , Patrizio Frosini , Tomasz Kaczynski , Claudia Landi

In the recent papers, we introduced a method utilised to measure the flow field. The method is based on the tracking of supergranular structures. We did not precisely know, whether its results represent the flow field in the photosphere or…

The Sun's internal structure and dynamics can be studied with helioseismology, which uses the Sun's natural acoustic oscillations to build up a profile of the solar interior. We discuss how solar acoustic oscillations are affected by the…

Solar and Stellar Astrophysics · Physics 2014-11-26 A. -M. Broomhall , P. Chatterjee , R. Howe , A. A. Norton , M. J. Thompson

Persistent homology, a technique from computational topology, has recently shown strong empirical performance in the context of graph classification. Being able to capture long range graph properties via higher-order topological features,…

Machine Learning · Computer Science 2024-12-20 Rubén Ballester , Bastian Rieck

The Sun is replete with magnetic fields, with sunspots, pores and plage regions being their most prominent representatives on the solar surface. But even far away from these active regions, magnetic fields are ubiquitous. To a large extent,…

Solar and Stellar Astrophysics · Physics 2015-11-05 Andreas Lagg , Bruce Lites , Jack Harvey , Sanjay Gosain , Rebecca Centeno

Recently, we have developed a method useful for mapping large-scale horizontal velocity fields in the solar photosphere. The method was developed, tuned and calibrated using the synthetic data. Now, we applied the method to the series of…

Astrophysics · Physics 2009-11-13 Michal Svanda , Mirek Klvana , Michal Sobotka , Vaclav Bumba

Magnetoseismology, a technique of magnetic field diagnostics based on observations of magnetohydrodynamic (MHD) waves, has been widely used to estimate the field strengths of oscillating structures in the solar corona. However, previously…

Solar and Stellar Astrophysics · Physics 2020-11-05 Zihao Yang , Hui Tian , Steven Tomczyk , Richard Morton , Xianyong Bai , Tanmoy Samanta , Yajie Chen

Context: The presence of a turbulent magnetic field in the quiet Sun has been unveiled observationally using different techniques. The magnetic field is quasi-isotropic and has field strengths weaker than 100G. It is pervasive and may host…

Solar and Stellar Astrophysics · Physics 2016-11-26 A. López Ariste , A. Sainz Dalda

As a large-scale motion on the Sun, the meridional flow plays an important role in determining magnetic structure and strength and solar cycle. However, the meridional flow near the solar poles is still unclear. The Hinode observations show…

Solar and Stellar Astrophysics · Physics 2024-07-29 Shuhong Yang , Jie Jiang , Zifan Wang , Yijun Hou , Chunlan Jin , Qiao Song , Yukun Luo , Ting Li , Jun Zhang , Yuzong Zhang , Guiping Zhou , Yuanyong Deng , Jingxiu Wang

The solar-stellar connection provides a unique framework for understanding magnetic activity and atmospheric heating across a broad spectrum of stars. Solar Dynamics Observatory (SDO) of NASA, equipped with the Helioseismic and Magnetic…

Solar and Stellar Astrophysics · Physics 2026-02-20 Shin Toriumi
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