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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

Context. Local correlation tracking of granulation (LCT) is an important method for measuring horizontal flows in the photosphere. This method exhibits a systematic error that looks like a flow converging towards disk center, also known as…

Solar and Stellar Astrophysics · Physics 2016-06-01 B. Löptien , A. C. Birch , T. L. Duvall , L. Gizon , J. Schou

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. Several upcoming and proposed space missions, such as Solar Orbiter, will be limited in telemetry and thus require data compression. Aims. We test the impact of data compression on local correlation tracking (LCT) of time-series of…

Solar and Stellar Astrophysics · Physics 2016-02-17 Björn Löptien , Aaron C. Birch , Tom L. Duvall , Laurent Gizon , Jesper Schou

Flow vorticity is a fundamental property of turbulent convection in rotating systems. Solar supergranules exhibit a preferred sense of rotation, which depends on the hemisphere. This is due to the Coriolis force acting on the diverging…

Solar and Stellar Astrophysics · Physics 2015-09-09 J. Langfellner , L. Gizon , A. C. Birch

We analyse mesogranular flow patterns in a three-dimensional hydrodynamical simulation of solar surface convection in order to determine its characteristics. We calculate divergence maps from horizontal velocities obtained with the Local…

Solar and Stellar Astrophysics · Physics 2015-05-19 Ł. Matloch , R. Cameron , S. Shelyag , D. Schmitt , M. Schüssler

We tested whether simultaneous spectropolarimetric imaging in two magnetically sensitive optical spectral lines, which probe two different layers of the solar atmosphere (the photosphere and the temperature minimum), can help constrain the…

Context. Local helioseismology has detected spatially extended converging surface flows into solar active regions. These play an important role in flux-transport models of the solar dynamo. Aims. We aim to validate the existence of the…

Solar and Stellar Astrophysics · Physics 2017-10-04 B. Löptien , A. C. Birch , T. L. Duvall , L. Gizon , B. Proxauf , J. Schou

High-resolution images of the solar surface show a granulation pattern of hot rising and cooler downward-sinking material -- the top of the deep-reaching solar convection zone. Convection plays a role for the thermal structure of the solar…

Solar and Stellar Astrophysics · Physics 2011-12-14 Bernd Freytag , Matthias Steffen , Hans-Günter Ludwig , Sven Wedemeyer-Böhm , Werner Schaffenberger , Oskar Steiner

We apply time-distance helioseismology, local correlation tracking and Fourier spatial-temporal filtering methods to realistic supergranule scale simulations of solar convection and compare the results with high-resolution observations from…

Local-box hydrodynamical model atmospheres provide statistical information about a star's emergent radiation field which allows one to predict the level of its granulation-related micro-variability. Space-based photometry is now…

Solar and Stellar Astrophysics · Physics 2015-05-13 H. -G. Ludwig , R. Samadi , M. Steffen , T. Appourchaux , F. Baudin , K. Belkacem , P. Boumier , M. -J. Goupil , E. Michel

We employ time sequences of images observed with a G-band filter (4305{\AA}) by the Solar Optical Telescope (SOT) on board of Hinode spacecraft at different latitude along solar central me-ridian to study vorticity of granular flows in…

Solar and Stellar Astrophysics · Physics 2017-02-02 A. A. Pevtsov

Radiative hydrodynamic simulations of solar and stellar surface convection have become an important tool for exploring the structure and gas dynamics in the envelopes and atmospheres of late-type stars and for improving our understanding of…

Solar and Stellar Astrophysics · Physics 2015-06-03 B. Beeck , R. Collet , M. Steffen , M. Asplund , R. H. Cameron , B. Freytag , W. Hayek , H. -G. Ludwig , M. Schüssler

Continuous high-cadence and high-spatial resolution Dopplergrams allow us to study sub-surface dynamics that may be further extended to explore precursors of visible solar activity on the surface. Since the p-mode power is absorbed in the…

Solar and Stellar Astrophysics · Physics 2016-01-20 Kiran Jain , S. C. Tripathy , B. Ravindra , R. Komm , F. Hill

We employ different shapes of apodizing windows in the local correlation tracking (LCT) routine to retrieve horizontal velocities using numerical simulations of convection. LCT was applied on a time sequence of temperature maps generated by…

Solar and Stellar Astrophysics · Physics 2015-06-23 Rohan E. Louis , B. Ravindra , Manolis K. Georgoulis , Manfred Küker

The granulation background seen in the power spectrum of a solar-like oscillator poses a serious challenge for extracting precise and detailed information about the stellar oscillations. Using a 3D hydrodynamical simulation of the Sun…

Solar and Stellar Astrophysics · Physics 2020-12-02 Mia S. Lundkvist , Hans-Günter Ludwig , Remo Collet , Thomas Straus

Hydrodynamic simulations of granular convection predict the existence of supersonic flows covering ~3-4% of the solar surface at any time, but these flows have not been detected unambigously as yet. Using data from the spectropolarimeter…

Solar and Stellar Astrophysics · Physics 2009-07-22 L. R. Bellot Rubio

We compare measurements of horizontal flows on the surface of the Sun using helioseismic time--distance inversions and coherent structure tracking of solar granules. Tracking provides 2D horizontal flows on the solar surface, whereas the…

Solar and Stellar Astrophysics · Physics 2015-06-15 M. Svanda , Th. Roudier , M. Rieutord , R. Burston , L. Gizon

A giant solar filament was visible on the solar surface from 2011 Nov. 8-23. The filament stretched over more than half a solar diameter. Multiwavelength data from the SDO instrument AIA (171, 193, 304, and 211\AA) were used to examine…

Solar and Stellar Astrophysics · Physics 2018-03-28 A. Diercke , C. Kuckein , M. Verma , C. Denker

The determination of horizontal velocity fields at the solar surface is crucial to understanding the dynamics and magnetism of the convection zone of the sun. These measurements can be done by tracking granules. Tracking granules from…

Astrophysics · Physics 2009-11-13 R. Tkaczuk , M. Rieutord , N. Meunier , T. Roudier
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