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Sunspots are prominent manifestations of the solar cycle and provide key constraints for understanding its operation. Also, knowing internal structure of sunspots allows us to gain insights on the energy transport in strong magnetic fields…

Solar and Stellar Astrophysics · Physics 2010-03-29 R. Wenzel , S. V. Berdyugina , D. M. Fluri , J. Arnaud , A. Sainz-Dalda

Solar pores are active regions with large magnetic field strengths and apparent simple magnetic configurations. Their properties resemble the ones found for the sunspot umbra although pores do not show penumbra. Therefore, solar pores…

Solar and Stellar Astrophysics · Physics 2016-06-15 C. Quintero Noda , T. Shimizu , B. Ruiz Cobo , Y. Suematsu , Y. Katsukawa , K. Ichimoto

The Mg I b$_2$ line at 5173 \r{A} is primarily magnetically sensitive to heights between the mid photosphere and the low chromosphere, a region that has not been sufficiently explored in the solar atmosphere but is crucial for understanding…

Solar and Stellar Astrophysics · Physics 2025-03-18 A. L. Siu-Tapia , L. R. Bellot Rubio , D. Orozco Suárez , R. Gafeira

Solar granules are bright patterns surrounded by dark channels called intergranular lanes in the solar photosphere and are a manifestation of overshooting convection. Observational studies generally find stronger upflows in granules and…

Solar and Stellar Astrophysics · Physics 2017-11-01 T. Oba , T. L. Riethmüller , S. K. Solanki , Y. Iida , C. Quintero Noda , T. Shimizu

We investigate a region of the quiet solar photosphere exhibiting three-lobed Stokes V profiles in the Fe I spectral line at 15648 Angstroem. The data were acquired with the GRIS spectropolarimeter attached to the GREGOR telescope. We aim…

Solar and Stellar Astrophysics · Physics 2018-08-29 Christoph Kiess , Juan Manuel Borrero , Wolfgang Schmidt

Using radiative magneto-hydrodynamic simulations of the magnetised solar photosphere and detailed spectro-polarimetric diagnostics with the FeI $6301.5\mathrm{\AA}$ and $6302.5\mathrm{\AA}$ photospheric lines in the local thermodynamic…

Solar and Stellar Astrophysics · Physics 2015-06-23 S. Shelyag

The aim of this work is to give new observational constraints on solar surface flows by determining the horizontal scale dependence of the velocity and intensity fields, as represented by their power spectra, and to offer some theoretical…

Solar and Stellar Astrophysics · Physics 2015-05-14 M. Rieutord , T. Roudier , F. Rincon , J. -M. Malherbe , N. Meunier , T. Berger , Z. Frank

We employ the magnetic and velocity fields from turbulent dynamo simulations to synthesize the polarization of a typical photospheric line. The synthetic Stokes profiles have properties in common with those observed in the quiet Sun. The…

Astrophysics · Physics 2009-11-07 J. Sánchez Almeida , T. Emonet , F. Cattaneo

The consistency of time--distance inversions for horizontal components of the plasma flow on supergranular scales in the upper solar convection zone is checked by comparing the results derived using two k--\omega filtering procedures --…

Solar and Stellar Astrophysics · Physics 2015-06-16 Michal Svanda

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

A quiet Sun magnetic flux cancelation event at the disk centre was recorded using the Integral Field Unit (IFU) mounted on the GREGOR Infrared Spectrograph (GRIS). GRIS sampled the event in the photospheric Si I 10827 {\AA} spectral line.…

Solar and Stellar Astrophysics · Physics 2020-02-26 Anjali. J. Kaithakkal , J. M. Borrero , C. E. Fischer , C. Dominguez-Tagle , M. Collados

The existence of asymmetries in the circular polarization (Stokes V) profiles emerging from the solar photosphere is known since the 1970s. These profiles require the presence of a velocity gradient along the line of sight, possibly…

Solar and Stellar Astrophysics · Physics 2012-03-06 A. Sainz Dalda , J. Martinez-Sykora , L. Bellot Rubio , A. Title

A new Stokes inversion technique that greatly reduces the effect of the spatial point spread function of the telescope is used to constrain the physical properties of umbral dots (UDs). The depth-dependent inversion of the Stokes parameters…

Solar and Stellar Astrophysics · Physics 2015-06-15 T. L. Riethmüller , S. K. Solanki , M. van Noort , S. K. Tiwari

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

During solar flares, spectral lines formed in the photosphere have been shown to exhibit changes to their profiles despite the challenges of energy transfer to these depths. Recent work has shown that deep-forming spectral lines are subject…

Solar and Stellar Astrophysics · Physics 2024-01-05 Aaron J. Monson , Mihalis Mathioudakis , Adam F. Kowalski

Plasma flow measurements in solar active region filaments are rare, particularly in the infrared and ultraviolet ranges that probe the chromosphere and transition region. In addition, previous studies generally focused on prominences and…

Solar and Stellar Astrophysics · Physics 2025-11-04 M. Murabito , V. Andretta , S. Parenti , C. Kuckein , S. J. Gonzàlez Manrique , S. M. Lezzi , S. L. Guglielmino

Solar granulation consists of dynamic convective plasma cells that rise from the solar interior to the surface. The interaction between these plasma cells and the Sun's magnetic field provides valuable insights into plasma dynamics near the…

Solar and Stellar Astrophysics · Physics 2026-04-01 J. I. Campos Rozo , J. Jurčák , S. M. Díaz Castillo , M. van Noort

We used spectropolarimetric observations of a sunspot in active region NOAA 11809 in the Ca ii line at 854.2 nm taken with the SpectroPolarimeter for Optical and Infrared Regions (SPINOR) at the Dunn Solar Telescope to infer thermodynamic…

Solar and Stellar Astrophysics · Physics 2018-04-23 Debi Prasad Choudhary , Christian Beck

We review (i) observations and numerical simulations of vortical flows in the solar atmosphere and (ii) measurements of the horizontal magnetic field in quiet Sun regions. First, we discuss various manifestations of vortical flows and…

Solar and Stellar Astrophysics · Physics 2012-02-21 O. Steiner , R. Rezaei

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