scholarly journals Vortex flow properties in simulations of solar plage region: Evidence for their role in chromospheric heating

2020 ◽  
Vol 645 ◽  
pp. A3
Author(s):  
N. Yadav ◽  
R. H. Cameron ◽  
S. K. Solanki
Keyword(s):  
Magnetic Flux ◽  
Physical Properties ◽  
Numerical Simulations ◽  
Solar Atmosphere ◽  
Small Scale ◽  
Flux Tubes ◽  
Current Sheets ◽  
Plage Region ◽  
Magnetic Flux Tubes ◽  
Chromospheric Heating

Context. Vortex flows exist across a broad range of spatial and temporal scales in the solar atmosphere. Small-scale vortices are thought to play an important role in energy transport in the solar atmosphere. However, their physical properties remain poorly understood due to the limited spatial resolution of the observations. Aims. We explore and analyze the physical properties of small-scale vortices inside magnetic flux tubes using numerical simulations, and investigate whether they contribute to heating the chromosphere in a plage region. Methods. Using the three-dimensional radiative magnetohydrodynamic simulation code MURaM, we perform numerical simulations of a unipolar solar plage region. To detect and isolate vortices we use the swirling strength criterion and select the locations where the fluid is rotating with an angular velocity greater than a certain threshold. We concentrate on small-scale vortices as they are the strongest and carry most of the energy. We explore the spatial profiles of physical quantities such as density and horizontal velocity inside these vortices. Moreover, to learn their general characteristics, a statistical investigation is performed. Results. Magnetic flux tubes have a complex filamentary substructure harboring an abundance of small-scale vortices. At the interfaces between vortices strong current sheets are formed that may dissipate and heat the solar chromosphere. Statistically, vortices have higher densities and higher temperatures than the average values at the same geometrical height in the chromosphere. Conclusions. We conclude that small-scale vortices are ubiquitous in solar plage regions; they are denser and hotter structures that contribute to chromospheric heating, possibly by dissipation of the current sheets formed at their interfaces.

The Characteristics of Thin Magnetic Flux Tubes in the Lower Solar Atmosphere Observed byHinode/SOT in the G band and in Ca ii H Bright Points

2017 ◽  
Vol 851 (1) ◽  
pp. 42 ◽  
Author(s):  
Jianping Xiong ◽  
Yunfei Yang ◽  
Chunlan Jin ◽  
Kaifan Ji ◽  
Song Feng ◽  
...  
Keyword(s):  
Magnetic Flux ◽  
Solar Atmosphere ◽  
Flux Tubes ◽  
Magnetic Flux Tubes ◽  
Lower Solar Atmosphere

scholarly journals The Small-Scale Photospheric Magnetic Field as an Indicator of the Dynamo

1993 ◽  
Vol 141 ◽  
pp. 143-146
Author(s):  
K. Petrovay ◽  
G. Szakály
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Magnetic Flux ◽  
Observational Data ◽  
Convective Zone ◽  
Small Scale ◽  
Dynamo Theory ◽  
Flux Tubes ◽  
Magnetic Flux Tubes ◽  
Surface Fields

AbstractThe presently widely accepted view that the solar dynamo operates near the base of the convective zone makes it difficult to relate the magnetic fields observed in the solar atmosphere to the fields in the dynamo layer. The large amount of observational data concerning photospheric magnetic fields could in principle be used to impose constraints on dynamo theory, but in order to infer these constraints the above mentioned “missing link” between the dynamo and surface fields should be found. This paper proposes such a link by modeling the passive vertical transport of thin magnetic flux tubes through the convective zone.

scholarly journals Numerical Simulations of Torsional Alfvén Waves in Axisymmetric Solar Magnetic Flux Tubes

Solar Physics ◽  
2017 ◽  
Vol 292 (2) ◽  
Author(s):  
D. Wójcik ◽  
K. Murawski ◽  
Z. E. Musielak ◽  
P. Konkol ◽  
A. Mignone
Keyword(s):  
Magnetic Flux ◽  
Numerical Simulations ◽  
Alfven Waves ◽  
Alfvén Waves ◽  
Flux Tubes ◽  
Magnetic Flux Tubes

scholarly journals Modelling 3D magnetic networks in a realistic solar atmosphere

2019 ◽  
Vol 489 (1) ◽  
pp. 28-35
Author(s):  
Frederick A Gent ◽  
Ben Snow ◽  
Viktor Fedun ◽  
Robertus Erdélyi
Keyword(s):  
Magnetic Field ◽  
Magnetic Flux ◽  
Solar Atmosphere ◽  
Energy Transport ◽  
Solar Dynamics Observatory ◽  
Lower Corona ◽  
Flux Tubes ◽  
Background Magnetic Field ◽  
Magnetic Flux Tubes ◽  
Open Magnetic Flux

ABSTRACT The magnetic network extending from the photosphere (solar radius ≃ R⊙) to the lower corona ($\mathrm{ R}_\odot +10\, {\rm Mm}$) plays an important role in the heating mechanisms of the solar atmosphere. Here we develop further the models of the authors with realistic open magnetic flux tubes, in order to model more complicated configurations. Closed magnetic loops and combinations of closed and open magnetic flux tubes are modelled. These are embedded within a stratified atmosphere, derived from observationally motivated semi-empirical and data-driven models subject to solar gravity and capable of spanning from the photosphere up into the chromosphere and lower corona. Constructing a magnetic field comprising self-similar magnetic flux tubes, an analytic solution for the kinetic pressure and plasma density is derived. Combining flux tubes of opposite polarity, it is possible to create a steady background magnetic field configuration, modelling a solar atmosphere exhibiting realistic stratification. The result can be applied to the Solar and Heliospheric Observatory Michelson Doppler Imager (SOHO/MDI), Solar Dynamics Observatory Helioseismic and Magnetic Imager (SDO/HMI) and other magnetograms from the solar surface, for which photospheric motions can be simulated to explore the mechanism of energy transport. We demonstrate this powerful and versatile method with an application to HMI data.

scholarly journals Probing the structure of local magnetic field of solar features with helioseismology

2013 ◽  
Vol 9 (S302) ◽  
pp. 126-129
Author(s):  
Khalil Daiffallah
Keyword(s):  
Magnetic Field ◽  
Magnetic Flux ◽  
Numerical Simulations ◽  
Cluster Model ◽  
Solar Magnetic Field ◽  
Local Magnetic Field ◽  
Flux Tubes ◽  
Field Activity ◽  
Magnetic Flux Tubes ◽  
Propagation Of Waves

AbstractMotivated by the problem of local solar subsurface magnetic structure, we have used numerical simulations to investigate the propagation of waves through monolithic magnetic flux tubes of different sizes. A cluster model can be a good approximation to simulate sunspots as well as solar plage regions which are composed of an ensemble of compactly packed thin flux tubes. Simulations of this type are powerful tools to probe the structure and the dynamics of various solar features which are directly related to solar magnetic field activity.

scholarly journals Theoretical Models of Magnetic Flux Tubes: Structure and Dynamics

1994 ◽  
Vol 154 ◽  
pp. 407-421
Author(s):  
O Steiner
Keyword(s):  
Magnetic Flux ◽  
Line Emission ◽  
Theoretical Models ◽  
Small Scale ◽  
Solar Photosphere ◽  
Model Calculations ◽  
Flux Tubes ◽  
Wide Range ◽  
Magnetic Flux Tubes ◽  
Lower Chromosphere

Two types of model calculations for small scale magnetic flux tubes in the solar atmosphere are reviewed. In the first kind, one follows the temporal evolution governed by the complete set of the MHD and radiative transfer equations to a (quasi) stationary solution. From such a solution the continuum contrasts of a photospheric flux tube in the visible and in the infrared continuum at 1.6 μm have been computed and are briefly discussed. The second, more empirical type of method assumes the flux tubes to be in magnetohydrostatic equilibrium. It is computationally faster and more flexible and allows us to explore a wide range of parameters. Models and insights obtained from such parameter studies are discussed in some detail. These include an explanation for the peculiar variation of the area asymmetry of Stokes V profiles across the solar disk in terms of mass motions in the surroundings of magnetic flux tubes.Furthermore, a two-dimensional model of the lower chromosphere that has been developed is presented. Emphasis is laid on the effect of thermal bifurcation of the lower chromosphere on the structure of the chromospheric magnetic field. If the cool carbon monoxide clouds, observed in the infrared, occupy the non-magnetic regions, the flux tubes expand very strongly and form a magnetic canopy with an almost horizontal base. This has consequences for the spatial distribution of the Ca II K spectral line emission.Finally, some consideration is given to the formation and destruction of intense magnetic flux tubes in the solar photosphere. The formation is described as a consequence of the flux expulsion process that leads to a convective instability. A possible observational signature of this mechanism is proposed.

scholarly journals Multi-scale dynamics of magnetic flux tubes and inverse magnetic energy transfer

2020 ◽  
Vol 86 (4) ◽  
Author(s):  
Muni Zhou ◽  
Nuno F. Loureiro ◽  
Dmitri A. Uzdensky
Keyword(s):  
Magnetic Flux ◽  
Time Evolution ◽  
Magnetic Energy ◽  
Numerical Study ◽  
Three Dimensional ◽  
Early Time ◽  
Small Scale ◽  
Flux Tubes ◽  
Seed Field ◽  
Magnetic Flux Tubes

We report on an analytical and numerical study of the dynamics of a three-dimensional array of identical magnetic flux tubes in the reduced-magnetohydrodynamic description of the plasma. We propose that the long-time evolution of this system is dictated by flux-tube mergers, and that such mergers are dynamically constrained by the conservation of the pertinent (ideal) invariants, viz. the magnetic potential and axial fluxes of each tube. We also propose that in the direction perpendicular to the merging plane, flux tubes evolve in a critically balanced fashion. These notions allow us to construct an analytical model for how quantities such as the magnetic energy and the energy-containing scale evolve as functions of time. Of particular importance is the conclusion that, like its two-dimensional counterpart, this system exhibits an inverse transfer of magnetic energy that terminates only at the system scale. We perform direct numerical simulations that confirm these predictions and reveal other interesting aspects of the evolution of the system. We find, for example, that the early time evolution is characterized by a sharp decay of the initial magnetic energy, which we attribute to the ubiquitous formation of current sheets. We also show that a quantitatively similar inverse transfer of magnetic energy is observed when the initial condition is a random, small-scale magnetic seed field.

Emergence of undulatory magnetic flux tubes by small scale reconnections

2006 ◽  
Vol 38 (5) ◽  
pp. 902-905 ◽  
Author(s):  
E. Pariat ◽  
G. Aulanier ◽  
B. Schmieder ◽  
M.K. Georgoulis ◽  
D.M. Rust ◽  
...  
Keyword(s):  
Magnetic Flux ◽  
Small Scale ◽  
Flux Tubes ◽  
Magnetic Flux Tubes
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