scholarly journals THE RELATIONSHIP BETWEEN EXTREME ULTRAVIOLET NON-THERMAL LINE BROADENING AND HIGH-ENERGY PARTICLES DURING SOLAR FLARES

2013 ◽  
Vol 775 (2) ◽  
pp. 122 ◽  
Author(s):  
T. Kawate ◽  
S. Imada
Keyword(s):  
Solar Flares ◽  
Extreme Ultraviolet ◽  
High Energy ◽  
Line Broadening ◽  
The Relationship ◽  
High Energy Particles ◽  
Thermal Line

scholarly journals Particle Acceleration in Solar Flares and Coronal Mass Ejections

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.

scholarly journals Non-thermal line broadening due to braiding-induced turbulence in solar coronal loops

2020 ◽  
Vol 639 ◽  
pp. A21 ◽  
Author(s):  
D. I. Pontin ◽  
H. Peter ◽  
L. P. Chitta
Keyword(s):  
Magnetic Field ◽  
Extreme Ultraviolet ◽  
Plasma Heating ◽  
Heating Process ◽  
Coronal Loops ◽  
Line Broadening ◽  
Magnetohydrodynamic Model ◽  
Non Gaussian ◽  
Thermal Line ◽  
Solar Coronal

Aims. Emission line profiles from solar coronal loops exhibit properties that are unexplained by current models. We investigate the non-thermal broadening associated with plasma heating in coronal loops that is induced by magnetic field line braiding. Methods. We describe the coronal loop by a 3D magnetohydrodynamic model of the turbulent decay of an initially-braided magnetic field. From this, we synthesised the Fe XII line at 193 Å that forms around 1.5 MK. Results. The key features of current observations of extreme ultraviolet (UV) lines from the corona are reproduced in the synthesised spectra: (i) Typical non-thermal widths range from 15 to 20 km s−1. (ii) The widths are approximately independent of the size of the field of view. (iii) There is a correlation between the line intensity and non-thermal broadening. (iv) Spectra are found to be non-Gaussian, with enhanced power in the wings of the order of 10–20%. Conclusions. Our model provides an explanation that self-consistently connects the heating process to the observed non-thermal line broadening. The non-Gaussian nature of the spectra is a consequence of the non-Gaussian nature of the underlying velocity fluctuations, which is interpreted as a signature of intermittency in the turbulence.

scholarly journals Fundamental physical processes in coronae: Waves, turbulence, reconnection, and particle acceleration

2007 ◽  
Vol 3 (S247) ◽  
pp. 257-268
Author(s):  
Markus J. Aschwanden
Keyword(s):  
Particle Acceleration ◽  
Solar Corona ◽  
Acoustic Waves ◽  
Plasma Heating ◽  
High Energy ◽  
X Rays ◽  
Line Broadening ◽  
Routine Basis ◽  
Related Line ◽  
High Energy Particles

AbstractOur understanding of fundamental processes in the solar corona has been greatly progressed based on the space observations of SMM, Yohkoh, Compton GRO, SOHO, TRACE, RHESSI, and STEREO. We observe now acoustic waves, MHD oscillations, turbulence-related line broadening, magnetic configurations related to reconnection processes, and radiation from high-energy particles on a routine basis. We review a number of key observations in EUV, soft X-rays, and hard X-rays that innovated our physical understanding of the solar corona, in terms of hydrodynamics, MHD, plasma heating, and particle acceleration processes.

scholarly journals Factors Determining Variability Time in Active Galactic Nucleus Jets

2002 ◽  
Vol 19 (4) ◽  
pp. 486-498 ◽  
Author(s):  
R. J. Protheroe
Keyword(s):  
Energy Density ◽  
Photon Energy ◽  
Temperature Limit ◽  
High Energy ◽  
Emission Region ◽  
Intrinsic Variability ◽  
Frame Size ◽  
The Relationship ◽  
High Energy Particles ◽  
Finite Particle

AbstractThe relationship between observed variability time and emission region geometry is explored for the case of emission by relativistic jets.The approximate formula for the jet-frame size of the emission region, R′ = DcΔtobs, is shown to lead to large systematic errors when used together with observed luminosity and assumed or estimated Doppler factor D to estimate the jet-frame photon energy density. These results have implications for AGN models in which low-energy photons are targets for interaction of high energy particles and photons, e.g. synchrotron-self Compton models and hadronic blazar models, as well as models of intraday variable sources in which the photon energy density imposes a brightness temperature limit through Compton scattering.The actual relationship between emission region geometry and observed variability is discussed for a variety of geometries including cylinders, spheroids, bent, helical and conical jet structures, and intrinsic variability models including shock excitation. The effects of time delays due to finite particle acceleration and radiation timescales are also discussed.

Relationship of EIT Waves Phenomena with Other Solar Phenomena

2021 ◽  
Author(s):  
Virendra Verma
Keyword(s):  
Solar Flares ◽  
Extreme Ultraviolet ◽  
Coronal Holes ◽  
Linear Velocity ◽  
Common Mechanism ◽  
Poor Correlation ◽  
Solar Winds ◽  
Relationship Of ◽  
The Relationship ◽  
Wave Phenomena

<p><br> In the present paper, we have studied the relationship between the Extreme Ultraviolet Imaging Telescope (EIT) waves phenomena with solar flares, coronal holes, solar winds, and coronal mass ejections (CMEs) events. The EIT/ SOHO instrument recorded 176 EIT events during the above period (March 25, 1997-June 17, 1998) and the EIT waves list was published by Thompson & Myers (2009). After temporal matching of EIT wave events with CMEs phenomena, we find that corresponding to 58 EIT wave events, no CMEs events were recorded and thus we excluded 58 EIT wave events from the present study. Out of 176 EIT wave events, only 106 are accompanied by CMEs phenomena. The correlation study of the speed of EIT wave events and CMEs events of 106  events shows poor correlation r= 0.32, indicate that the EIT waves and CMEs events do not have a common mechanism of origin, and also indicate that some other factor is working in the formation of  CMEs from EIT waves. Further, We have also matched the spatial matching EIT wave sources as indicated by Thomson & Myers (2009) with CHs and flares and found that CMEs appear to be associated with EIT wave phenomena and CHs.  Earlier Verma & Pande (1989), Verma (1998) indicated that the CMEs may have been produced by some mechanism, in which the mass ejected by solar flares or active prominences, gets connected with the open magnetic lines of CHs (source of high-speed solar wind streams) and moves along them to appear as CMEs. Most recently Verma & Mittal (2019)  proposed a  methodology to understand the origin of CMEs through magnetic reconnection of   CHs and solar flares.  In the present paper, we proposed a scenario/ 2-dimensional model, in which the origin of CMEs through reconnection of EIT waves and solar winds coming from the CHs and also found that the calculated CMEs velocity after reconnection of EIT waves and solar winds coming from the CHs are in very close to the observed CMEs linear velocity. We also calculated the value of the correlation coefficient between the observed linear velocity of CME events and the calculated value of CMEs velocity after reconnection and found the value as r=0.884. The value of correlation as r=0.884 is excellent and supports the proposed methodology.  Finally, we have also discussed the relationship of EIT wave phenomena with other solar phenomena, in view of the latest scenario of solar heliophysics phenomena.</p><p> </p><p> </p><p>References:</p><p>Thompson, B. J. & Myers, D. C. (2009) APJS, 183, 225.<br>Verma, V. K. & Pande, M. C. (1989) Proc. IAU Colloq. 104 Solar and Stellar Flares (Poster Papers), Stanford University, Stanford, USA, p.239.<br>Verma, V. K.(1998) Journal of Geophysical Indian Union, 2, 65.<br>Verma, V. K. & Mittal, N.(2019) Astronomy Letters, 45, 164-</p>

Particle acceleration and the decay of soft X-ray non-thermal line broadening in solar flares

Solar Physics ◽  
1994 ◽  
Vol 154 (1) ◽  
pp. 157-175 ◽  
Author(s):  
David Alexander ◽  
Sarah A. Matthews
Keyword(s):  
Particle Acceleration ◽  
Solar Flares ◽  
Line Broadening ◽  
X Ray ◽  
Thermal Line
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