On the relationship between solar flares, coronal mass ejections, and post-eruption energy release

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.

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Particle Acceleration in Solar Flares and Coronal Mass Ejections

Symposium - International Astronomical Union ◽

10.1017/s0074180900162746 ◽

2000 ◽

Vol 195 ◽

pp. 15-25

Author(s):

R. P. Lin

Keyword(s):

Particle Acceleration ◽

Energy Release ◽

Coronal Mass Ejections ◽

Solar Flares ◽

Gamma Ray ◽

Solar Energetic Particle ◽

High Energy ◽

Total Rate ◽

Solar Energetic Particle Events ◽

High Energy Particles

The Sun accelerates ions up to tens of GeV and electrons up to 100s of MeV in solar flares and coronal mass ejections. The energy in the accelerated tens-of-keV electrons and possibly ~1 MeV ions constitutes a significant fraction of the total energy released in a flare, implying that the particle acceleration and flare energy release mechanisms are intimately related. The total rate of energy release in transients from flares down to microflares/nanoflares may be significant for heating the active solar corona.Shock waves driven by fast CMEs appear to accelerate the high-energy particles in large solar energetic particle events detected at 1 AU. Smaller SEP events are dominated by ~1 to tens-of-keV electrons, with low fluxes of up to a few MeV/nucleon ions, typically enriched in 3He. The acceleration in gamma-ray flares appears to resemble that in these small electron-3He SEP events.

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The relationship between coronal mass ejections and solar flares

Advances in Space Research ◽

10.1016/0273-1177(84)90197-2 ◽

1984 ◽

Vol 4 (7) ◽

pp. 279-282 ◽

Cited By ~ 13

Author(s):

G.M. Simnett ◽

R.A. Harrison

Keyword(s):

Coronal Mass Ejections ◽

Solar Flares ◽

The Relationship

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Mechanism of Coronal Mass Ejections Triggered by Emerging Flux

Highlights of Astronomy ◽

10.1017/s1539299600013873 ◽

2002 ◽

Vol 12 ◽

pp. 394

Author(s):

P.F. Chen ◽

C. Fang ◽

K. Shibata

Keyword(s):

Magnetic Field ◽

Coronal Mass Ejections ◽

Solar Flares ◽

Solar Physics ◽

Flux Rope ◽

Outer Edge ◽

Trigger Mechanism ◽

Bottom Boundary ◽

Filament Channel ◽

The Relationship

The origin of coronal mass ejections (CMEs) is an interesting, while still mysterious, subject in solar physics. As well, the relationship between CMEs and solar flares is poorly understood. This paper attempts to provide answers to these questions on the base of the flux rope model, and put forward a trigger mechanism for CMEs. The work is motivated by an interesting discovery of the relation between reconnection-favored emerging flux and CMEs (Feynman and Martin 1995), i.e., such emerging flux, either within the filament channel or on the outer edge of the channel, can trigger CMEs.In the consideration of Aly’s constraint, a detached flux rope model was proposed for the pre-CME configuration. A quadrupolar magnetic field with a flux rope is introduced as the initial magnetic configuration in current research. Since our trigger mechanism is magnetic in nature, gravity is omitted. Emerging flux is simulated by changing the local magnetic flux at the bottom boundary.

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Research on the Ignition Height and Reaction Flame Temperature of PTFE/Al/Si/CuO with Different Mass Ratios of PTFE/Si

Materials ◽

10.3390/ma14133464 ◽

2021 ◽

Vol 14 (13) ◽

pp. 3464

Author(s):

Xuan Zou ◽

Jingyuan Zhou ◽

Xianwen Ran ◽

Yiting Wu ◽

Ping Liu ◽

...

Keyword(s):

Energy Release ◽

High Speed ◽

Flame Temperature ◽

Sintering Process ◽

Release Process ◽

Reactive Material ◽

Temperature Changes ◽

Release Capacity ◽

Mass Ratios ◽

The Relationship

Recent studies have shown that the energy release capacity of Polytetrafluoroethylene (PTFE)/Al with Si, and CuO, respectively, is higher than that of PTFE/Al. PTFE/Al/Si/CuO reactive materials with four proportions of PTFE/Si were designed by the molding–sintering process to study the influence of different PTFE/Si mass ratios on energy release. A drop hammer was selected for igniting the specimens, and the high-speed camera and spectrometer systems were used to record the energy release process and the flame spectrum, respectively. The ignition height of the reactive material was obtained by fitting the relationship between the flame duration and the drop height. It was found that the ignition height of PTFE/Al/Si/CuO containing 20% PTFE/Si is 48.27 cm, which is the lowest compared to the ignition height of other Si/PTFE ratios of PTFE/Al/Si/CuO; the flame temperature was calculated from the flame spectrum. It was found that flame temperature changes little for the same reactive material at different drop heights. Compared with the flame temperature of PTFE/Al/Si/CuO with four mass ratios, it was found that the flame temperature of PTFE/Al/Si/CuO with 20% PTFE/Si is the highest, which is 2589 K. The results show that PTFE/Al/Si/CuO containing 20% PTFE/Si is easier to be ignited and has a stronger temperature destruction effect.

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Some kinematics of halo coronal mass ejections

Open Astronomy ◽

10.1515/astro-2020-0010 ◽

2020 ◽

Vol 29 (1) ◽

pp. 81-88

Author(s):

Virendra Kumar Verma ◽

Nishant Mittal ◽

Ramesh Chandra

Keyword(s):

Coronal Mass Ejections ◽

Solar Flares ◽

Coronal Holes ◽

Geomagnetic Disturbances ◽

Class A ◽

Heliospheric Physics ◽

Class B ◽

The Mean ◽

Class C

AbstractWe present an investigation of halo coronal mass ejections (HCMEs) kinematics and other facts about the HCMEs. The study of HCMEs is very important because HCMEs are regarded as the main causes of heliospheric and geomagnetic disturbances. In this study, we have investigated 313 HCMEs observed during 1996-2012 by LASCO, coronal holes, and solar flares. We find that HCMEs are of two types: accelerated HCMEs and decelerated HCMEs. The mean space speed of HCMEs is 1283 km/s while the mean speed of decelerated HCMEs and accelerated HCMEs is 1349 km/s and 1174 km/s, respectively. The investigation shows that 1 (0.3%) HCME was associated with class A SXR, 14 (4.7%) HCMEs were associated with class B SXR-flares, 87 (29.4%) HCMEs were associated with class C SXR-flares, 125 (42.2%) HCMEs were associated with class M SXR-flares and 69 (23.3%) HCMEs were associated with class X SXR-flares. The speed of HCMEs increases with the importance of solar SXR-flares. The various results obtained in the present analysis are discussed in the light of the existing scenario of heliospheric physics.

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Gamma-rays from Solar Flares

Symposium - International Astronomical Union ◽

10.1017/s0074180900162850 ◽

2000 ◽

Vol 195 ◽

pp. 123-132 ◽

Cited By ~ 7

Author(s):

R. Ramaty ◽

N. Mandzhavidze

Keyword(s):

Energy Release ◽

Gamma Rays ◽

Solar Flares ◽

Gamma Ray ◽

Particle Interaction ◽

Mass Motion ◽

Relativistic Electrons ◽

Total Energy Release ◽

Flare Energy ◽

Accelerated Particles

Gamma-ray emission is the most direct diagnostic of energetic ions and relativistic electrons in solar flares. Analysis of solar flare gamma-ray data has shown: (i) ion acceleration is a major consequence of flare energy release, as the total flare energy in accelerated particles appears to be equipartitioned between ≳ 1 MeV/nucleon ions and ≳ 20 keV electrons, and amounts to an important fraction of the total energy release; (ii) there are flares for which over 50% of the energy is in a particles and heavier ions; (iii) in both impulsive and gradual flares, the particles that interact at the Sun and produce gamma rays are essentially always accelerated by the same mechanism that operates in impulsive flares, probably stochastic acceleration through gyroresonant wave particle interaction; and (iv) gamma-ray spectroscopy can provide new information on solar abundances, for example the site of the FIP-bias onset and the photospheric 3He abundance. We propose a new technique for the investigation of mass motion and mixing in the solar atmosphere: the observations of gamma-ray lines from long-term radioactivity produced by flare accelerated particles.

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