scholarly journals Global Forces in Eruptive Solar Flares: The Lorentz Force Acting on the Solar Atmosphere and the Solar Interior

Solar Physics ◽  
2011 ◽  
Vol 277 (1) ◽  
pp. 59-76 ◽  
Author(s):  
G. H. Fisher ◽  
D. J. Bercik ◽  
B. T. Welsch ◽  
H. S. Hudson
Keyword(s):  
Lorentz Force ◽  
Solar Atmosphere ◽  
Solar Flares ◽  
Solar Interior

scholarly journals What can He II 304 Å tell us about transient seismic emission from solar flares?

2016 ◽  
Vol 12 (S327) ◽  
pp. 113-116
Author(s):  
C. Lindsey ◽  
A. C. Donea
Keyword(s):  
Lorentz Force ◽  
Solar Flares ◽  
Solar Interior ◽  
Solar Dynamics Observatory ◽  
Transient Heating ◽  
Seismic Emission ◽  
Source Regions ◽  
Solar Dynamics

AbstractAfter neary 20 years since their discovery by Kosovichev and Zharkova, the mechanics of the release of seismic transients into the solar interior from some flares remain a mystery. Seismically emissive flares invariably show the signatures of intense chromosphere heating consistent with pressure variations sufficient to drive seismic transients commensurate with helioseismic observations—under certain conditions. Magnetic observations show the signatures of apparent magnetic changes, suggesting Lorentz-force transients that could likewise drive seismic transients—similarly subject to certain conditions. But, the diagnostic signatures of both of these prospective drivers are apparent over vast regions from which no significant seismic emission emanates. What distinguishes the source regions of transient seismic emission from the much vaster regions that show the signatures of both transient heating and magnetic variations but are acoustically unproductive? Observations of acoustically active flares in He II 304 Å by the Atomospheric Imaging Assembly (AIA) aboard the Solar Dynamics Observatory (SDO) offer a promising new resource with which to address this question.

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 Commission 12: Radiation and Structure of the Solar Atmosphere (Radiation et Structure de L’Atmosphere Solaire)

1991 ◽  
Vol 21 (1) ◽  
pp. 85-103
Keyword(s):  
Solar Atmosphere ◽  
Executive Committee ◽  
Solar Interior ◽  
Solar Structure ◽  
The Past ◽  
Solar Research ◽  
The One

This report was planned in cooperation with Commission 10. Both this report and the one of Commission 10 together give a coordinated overview of published developments in solar research during the past three years. For several years, the scope of Commission 12 has included not only the areas indicated by the title of the Commission but also the structure of the solar interior. This broadening of coverage has led to a proposed renaming of this Commission: Solar Structure, which is currently under consideration by the IAU Executive Committee.

scholarly journals X-ray jets and magnetic flux emergence in the Sun

2008 ◽  
Vol 4 (S259) ◽  
pp. 201-210
Author(s):  
Fernando Moreno-Insertis
Keyword(s):  
Magnetic Flux ◽  
Solar Atmosphere ◽  
Numerical Experiments ◽  
High Speed ◽  
Computational Effort ◽  
Plasma Jets ◽  
Solar Interior ◽  
Magnetized Plasma ◽  
Flux Emergence ◽  
X Ray

AbstractMagnetized plasma is emerging continually from the solar interior into the atmosphere. Magnetic flux emergence events and their consequences in the solar atmosphere are being observed with high space, time and spectral resolution by a large number of space missions in operation at present (e.g. SOHO, Hinode, Stereo, Rhessi). The collision of an emerging and a preexisting magnetic flux system in the solar atmosphere leads to the formation of current sheets and to field line reconnection. Reconnection under solar coronal conditions is an energetic event; for the field strengths, densities and speeds involved in the collision of emerging flux systems, the reconnection outflows lead to launching of high-speed (hundreds of km/s), high-temperature (107 K) plasma jets. Such jets are being observed with the X-Ray and EUV detectors of ongoing satellite missions. On the other hand, the spectacular increase in computational power in recent years permits to carry out three-dimensional numerical experiments of the time evolution of flux emerging systems and the launching of jets with a remarkable degree of detail.In this review, observation and modeling of the solar X-Ray jets are discussed. A two-decade long computational effort to model the magnetic flux emergence events by different teams has led to numerical experiments which explain, even quantitatively, many of the observed features of the X-ray jets. The review points out that, although alternative mechanisms must be considered, flux emergence is a prime candidate to explain the launching of the solar jets.

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

scholarly journals Explosion of sungrazing comets in the solar atmosphere and solar flares

2008 ◽  
Vol 4 (S257) ◽  
pp. 341-343 ◽  
Author(s):  
S. Ibadov ◽  
F. S. Ibodov ◽  
S. S. Grigorian
Keyword(s):  
Solar Activity ◽  
Solar Atmosphere ◽  
Solar Flares ◽  
Solar Surface ◽  
The Body ◽  
High Time Resolution ◽  
Solar Chromosphere ◽  
X Rays ◽  
Frontal Surface ◽  
Sungrazing Comets

AbstractExplosive evolution of nuclei of sungrazing comets near the solar surface, which occurs at conditions of intense interaction between the solar atmosphere and falling high-velocity comet nuclei as well as the relation of the phenomenon to the character of solar activity are analytically considered. It is found that, due to aerodynamic fragmentation of the falling body in the solar chromosphere and transversal expansion of the fragmented mass under the action of pressure gradient on the frontal surface, thermalization of the kinetic energy of the body occurs by sharp stopping of the disklike hypervelocity fragmented mass near the solar surface within a relatively very thin subphotospheric layer and has, therefore, an essentially impulsive and strongly explosive character. The specific energy release in the explosion region, erg/g, considerably exceeds the evaporation/sublimation heat of the body so that the process is accompanied by production of a high-temperature plasma. The energetics of such an explosive process corresponds to that of very large solar flares for falling bodies having masses equal to the mass of the nucleus of Comet Halley. Spectral observations of sungrazing comets by SOHO-like telescopes in a wide spectral range, including X rays, with a high time resolution, of the order of 0.1–10 s, are important for revealing solar activity in the form of an impact-generated photospheric flare.

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