scholarly journals Extreme Ultra-Violet Spectroscopy of the Lower Solar Atmosphere During Solar Flares (Invited Review)

Solar Physics ◽  
2015 ◽  
Vol 290 (12) ◽  
pp. 3399-3423 ◽  
Author(s):  
Ryan O. Milligan
Keyword(s):  
Solar Atmosphere ◽  
Solar Flares ◽  
Ultra Violet ◽  
Lower Solar Atmosphere

scholarly journals The Influence of Solar Flares on the Lower Solar Atmosphere: Evidence from the Na D Absorption Line Measured by GOLF/SOHO

Solar Physics ◽  
2010 ◽  
Vol 263 (1-2) ◽  
pp. 153-162 ◽  
Author(s):  
G. Cessateur ◽  
M. Kretzschmar ◽  
T. Dudok de Wit ◽  
P. Boumier
Keyword(s):  
Absorption Line ◽  
Solar Atmosphere ◽  
Solar Flares ◽  
Lower Solar Atmosphere

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

Estimation of the Energy Flux of Torsional Alfvén Waves in the Lower Solar Atmosphere Based on Measurements of the Doppler Velocities

2021 ◽  
Vol 61 (7) ◽  
pp. 1035-1037
Author(s):  
Yu. T. Tsap ◽  
A. V. Stepanov ◽  
Yu. G. Kopylova ◽  
O. V. Khaneychuk ◽  
T. B. Goldvarg
Keyword(s):  
Solar Atmosphere ◽  
Energy Flux ◽  
Alfven Waves ◽  
Alfvén Waves ◽  
Lower Solar Atmosphere

scholarly journals Magnetic reconnection resulting from flux emergence: implications for jet formation in the lower solar atmosphere?

2011 ◽  
Vol 535 ◽  
pp. A95 ◽  
Author(s):  
J. Y. Ding ◽  
M. S. Madjarska ◽  
J. G. Doyle ◽  
Q. M. Lu ◽  
K. Vanninathan ◽  
...  
Keyword(s):  
Magnetic Reconnection ◽  
Solar Atmosphere ◽  
Flux Emergence ◽  
Jet Formation ◽  
Lower Solar Atmosphere

scholarly journals The Role of Eruption in Solar Flares

1989 ◽  
Vol 104 (1) ◽  
pp. 387-397
Author(s):  
Peter A. Sturrock
Keyword(s):  
Energy Release ◽  
Solar Atmosphere ◽  
Coronal Mass Ejections ◽  
Solar Flares ◽  
Thought Experiments ◽  
Physical Behavior ◽  
Current Interruption ◽  
Flare Process ◽  
Plasma Configuration

AbstractThis article focuses on two problems involved in the development of models of solar flares. The first concerns the mechanism responsible for eruptions, such as erupting filaments or coronal mass ejections, that are sometimes involved in the flare process. The concept of ‘loss of equilibrium’ is considered and it is argued that the concept typically arises in thought-experiments that do not represent acceptable physical behavior of the solar atmosphere. It is proposed instead that such eruptions are probably caused by an instability of a plasma configuration. The instability may be purely MHD, or it may combine both MHD and resistive processes. The second problem concerns the mechanism of energy release of the impulsive (or gradual) phase. It is proposed that this phase of flares may be due to current interruption, as was originally proposed by Alfvén and Carlqvist. However, in order for this process to be viable, it seems necessary to change one's ideas about the heating and structure of the corona in ways that are outlined briefly.

scholarly journals Numerical simulations of the lower solar atmosphere heating by two-fluid nonlinear Alfvén waves

2020 ◽  
Vol 639 ◽  
pp. A45
Author(s):  
B. Kuźma ◽  
D. Wójcik ◽  
K. Murawski ◽  
D. Yuan ◽  
S. Poedts
Keyword(s):  
Magnetic Flux ◽  
Numerical Simulations ◽  
Solar Atmosphere ◽  
Flux Tube ◽  
Alfven Waves ◽  
Alfven Wave ◽  
Magnetic Flux Tube ◽  
Alfvén Waves ◽  
Two Fluid ◽  
Lower Solar Atmosphere

Context. We present new insight into the long-standing problem of plasma heating in the lower solar atmosphere in terms of collisional dissipation caused by two-fluid Alfvén waves. Aims. Using numerical simulations, we study Alfvén wave propagation and dissipation in a magnetic flux tube and their heating effect. Methods. We set up 2.5-dimensional numerical simulations with a semi-empirical model of a stratified solar atmosphere and a force-free magnetic field mimicking a magnetic flux tube. We consider a partially ionized plasma consisting of ion + electron and neutral fluids, which are coupled by ion-neutral collisions. Results. We find that Alfvén waves, which are directly generated by a monochromatic driver at the bottom of the photosphere, experience strong damping. Low-amplitude waves do not thermalize sufficient wave energy to heat the solar atmospheric plasma. However, Alfvén waves with amplitudes greater than 0.1 km s−1 drive through ponderomotive force magneto-acoustic waves in higher atmospheric layers. These waves are damped by ion-neutral collisions, and the thermal energy released in this process leads to heating of the upper photosphere and the chromosphere. Conclusions. We infer that, as a result of ion-neutral collisions, the energy carried initially by Alfvén waves is thermalized in the upper photosphere and the chromosphere, and the corresponding heating rate is large enough to compensate radiative and thermal-conduction energy losses therein.

scholarly journals Mode conversion of two-fluid shocks in a partially-ionised, isothermal, stratified atmosphere

2020 ◽  
Vol 637 ◽  
pp. A97
Author(s):  
B. Snow ◽  
A. Hillier
Keyword(s):  
Solar Atmosphere ◽  
Mode Conversion ◽  
Frictional Heating ◽  
Fast Mode ◽  
Compressional Waves ◽  
Pressure Scale ◽  
Velocity Drift ◽  
Two Fluid ◽  
Lower Solar Atmosphere

Context. The plasma of the lower solar atmosphere consists of mostly neutral particles, whereas the upper solar atmosphere is mostly made up of ionised particles and electrons. A shock that propagates upwards in the solar atmosphere therefore undergoes a transition where the dominant fluid is either neutral or ionised. An upwards propagating shock also passes a point where the sound and Alfvén speed are equal. At this point the energy of the acoustic shock can separated into fast and slow components. The way the energy is distributed between the two modes depends on the angle of magnetic field. Aims. We aim to investigate the separation of neutral and ionised species in a gravitationally stratified atmosphere. The role of two-fluid effects on the structure of the shocks post-mode-conversion and the frictional heating is quantified for different levels of collisional coupling. Methods. Two-fluid numerical simulations were performed using the (PIP) code of a wave steepening into a shock in an isothermal, partially-ionised atmosphere. The collisional coefficient was varied to investigate the regimes where the plasma and neutral species are weakly, strongly, and finitely coupled. Results. The propagation speeds of the compressional waves hosted by neutral and ionised species vary and, therefore, velocity drift between the two species is produced as the plasma attempts to propagate faster than the neutrals. This is most extreme for a fast-mode shock. We find that the collisional coefficient drastically impacts the features present in the system, specifically the mode conversion height, type of shocks present, and the finite shock widths created by the two-fluid effects. In the finitely-coupled regime, fast-mode shock widths can exceed the pressure scale height, which may lead to a new potential observable of two-fluid effects in the lower solar atmosphere.

scholarly journals Generation of solar spicules and subsequent atmospheric heating

Science ◽  
2019 ◽  
Vol 366 (6467) ◽  
pp. 890-894 ◽  
Author(s):  
Tanmoy Samanta ◽  
Hui Tian ◽  
Vasyl Yurchyshyn ◽  
Hardi Peter ◽  
Wenda Cao ◽  
...  
Keyword(s):  
Solar Atmosphere ◽  
Opposite Polarity ◽  
Solar Observatory ◽  
Magnetized Plasma ◽  
Solar Chromosphere ◽  
Solar Dynamics Observatory ◽  
Polarity Magnetic Field ◽  
Solar Dynamics ◽  
Solar Spicules ◽  
Lower Solar Atmosphere

Spicules are rapidly evolving fine-scale jets of magnetized plasma in the solar chromosphere. It remains unclear how these prevalent jets originate from the solar surface and what role they play in heating the solar atmosphere. Using the Goode Solar Telescope at the Big Bear Solar Observatory, we observed spicules emerging within minutes of the appearance of opposite-polarity magnetic flux around dominant-polarity magnetic field concentrations. Data from the Solar Dynamics Observatory showed subsequent heating of the adjacent corona. The dynamic interaction of magnetic fields (likely due to magnetic reconnection) in the partially ionized lower solar atmosphere appears to generate these spicules and heat the upper solar atmosphere.

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