Kinematics and Differential Emission Measure of the Flux Rope during Coronal Mass Ejections

2012 ◽  
Vol 55 ◽  
pp. 287-291
Author(s):  
M.D. Ding ◽  
X. Cheng ◽  
J. Zhang
Keyword(s):  
Coronal Mass Ejections ◽  
Emission Measure ◽  
Flux Rope ◽  
Differential Emission Measure

scholarly journals ON THE ACCURACY OF THE DIFFERENTIAL EMISSION MEASURE DIAGNOSTICS OF SOLAR PLASMAS. APPLICATION TO SDO /AIA. II. MULTITHERMAL PLASMAS

2012 ◽  
Vol 203 (2) ◽  
pp. 26 ◽  
Author(s):  
C. Guennou ◽  
F. Auchère ◽  
E. Soubrié ◽  
K. Bocchialini ◽  
S. Parenti ◽  
...  
Keyword(s):  
Emission Measure ◽  
Differential Emission Measure ◽  
Solar Plasmas

Analysis of the differential emission measure distributions for solar flares observed by RESIK

2018 ◽  
Vol 179 ◽  
pp. 545-552
Author(s):  
A. Kepa ◽  
B. Sylwester ◽  
J. Sylwester ◽  
M. Gryciuk ◽  
M. Siarkowski
Keyword(s):  
Solar Flares ◽  
Emission Measure ◽  
Differential Emission Measure

scholarly journals Energetics of Hi-C EUV brightenings

2018 ◽  
Vol 615 ◽  
pp. A47 ◽  
Author(s):  
Srividya Subramanian ◽  
Vinay L. Kashyap ◽  
Durgesh Tripathi ◽  
Maria S. Madjarska ◽  
John G. Doyle
Keyword(s):  
High Resolution ◽  
Energy Loss ◽  
Extreme Ultraviolet ◽  
Thermal Structure ◽  
Emission Measure ◽  
Light Curves ◽  
Solar Dynamics Observatory ◽  
Differential Emission Measure ◽  
Dominant Mechanism ◽  
Solar Dynamics

We study the thermal structure and energetics of the point-like extreme ultraviolet (EUV) brightenings within a system of fan loops observed in the active region AR 11520. These brightenings were simultaneously observed on 2012 July 11 by the High-resolution Coronal (Hi-C) imager and the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory (SDO). We identified 27 brightenings by automatically determining intensity enhancements in both Hi-C and AIA 193 Å light curves. The energetics of these brightenings were studied using the Differential Emission Measure (DEM) diagnostics. The DEM weighted temperatures of these transients are in the range log T(K) = 6.2−6.6 with radiative energies ≈1024−25 ergs and densities approximately equal to a few times 109 cm−3. To the best of our knowledge, these are the smallest brightenings in EUV ever detected. We used these results to determine the mechanism of energy loss in these brightenings. Our analysis reveals that the dominant mechanism of energy loss for all the identified brightenings is conduction rather than radiation.

scholarly journals Hydrogen non-equilibrium ionisation effects in coronal mass ejections

2020 ◽  
Vol 637 ◽  
pp. A49
Author(s):  
P. Pagano ◽  
A. Bemporad ◽  
D. H. Mackay
Keyword(s):  
Magnetic Flux ◽  
Visible Light ◽  
Coronal Mass Ejections ◽  
Flux Rope ◽  
Neutral Hydrogen ◽  
Hydrogen Atoms ◽  
Mhd Simulation ◽  
Magnetic Flux Rope ◽  
New Generation ◽  
Non Equilibrium

Context. A new generation of coronagraphs used to study solar wind and coronal mass ejections (CMEs) are being developed and launched. These coronagraphs will heavily rely on multi-channel observations where visible light (VL) and UV-EUV (ultraviolet-extreme ultraviolet) observations provide new plasma diagnostics. One of these instruments, Metis on board ESA-Solar Orbiter, will simultaneously observe VL and the UV Lyman-α line. The number of neutral hydrogen atoms (a small fraction of coronal protons) is a key parameter for deriving plasma properties, such as the temperature from the observed Lyman-α line intensity. However, these measurements are significantly affected if non-equilibrium ionisation effects occur, which can be relevant during CMEs. Aims. The aim of this work is to determine if non-equilibrium ionisation effects are relevant in CMEs and, in particular, when and in which regions of the CME plasma ionisation equilibrium can be assumed for data analysis. Methods. We used a magneto-hydrodynamic (MHD) simulation of a magnetic flux rope ejection to generate a CME. From this, we then reconstructed the ionisation state of hydrogen atoms in the CME by evaluating both the advection of neutral and ionised hydrogen atoms and the ionisation and recombination rates in the MHD simulation. Results. We find that the equilibrium ionisation assumption mostly holds in the core of the CME, which is represented by a magnetic flux rope. In contrast, non-equilibrium ionisation effects are significant at the CME front, where we find about 100 times more neutral hydrogen atoms than prescribed by ionisation equilibrium conditions. We find this to be the case even if this neutral hydrogen excess might be difficult to identify due to projection effects. Conclusions. This work provides key information for the development of a new generation of diagnostic techniques that aim to combine visible light and Lyman-α line emissions. The results show that non-equilibrium ionisation effects need to be considered when we analyse CME fronts. Incorrectly assuming equilibrium ionisation in these regions would lead to a systematic underestimate of plasma temperatures.

scholarly journals Do All Interplanetary Coronal Mass Ejections Have a Magnetic Flux Rope Structure Near 1 au?

2020 ◽  
Vol 901 (2) ◽  
pp. L21
Author(s):  
H. Q. Song ◽  
J. Zhang ◽  
X. Cheng ◽  
G. Li ◽  
Q. Hu ◽  
...  
Keyword(s):  
Magnetic Flux ◽  
Coronal Mass Ejections ◽  
Flux Rope ◽  
Interplanetary Coronal Mass Ejections ◽  
Magnetic Flux Rope

scholarly journals Observations of flux rope formation prior to coronal mass ejections

2013 ◽  
Vol 8 (S300) ◽  
pp. 209-214 ◽  
Author(s):  
Lucie M. Green ◽  
Bernhard Kliem
Keyword(s):  
Magnetic Flux ◽  
Magnetic Structure ◽  
Solar Atmosphere ◽  
Coronal Mass Ejections ◽  
Flux Rope ◽  
Active Regions ◽  
Magnetic Configuration ◽  
Magnetic Flux Rope ◽  
Source Regions ◽  
Flux Ropes

AbstractUnderstanding the magnetic configuration of the source regions of coronal mass ejections (CMEs) is vital in order to determine the trigger and driver of these events. Observations of four CME productive active regions are presented here, which indicate that the pre-eruption magnetic configuration is that of a magnetic flux rope. The flux ropes are formed in the solar atmosphere by the process known as flux cancellation and are stable for several hours before the eruption. The observations also indicate that the magnetic structure that erupts is not the entire flux rope as initially formed, raising the question of whether the flux rope is able to undergo a partial eruption or whether it undergoes a transition in specific flux rope configuration shortly before the CME.

scholarly journals The Slowly Varying Corona. I. Daily Differential Emission Measure Distributions Derived from EVE Spectra

2017 ◽  
Vol 844 (2) ◽  
pp. 163 ◽  
Author(s):  
S. J. Schonfeld ◽  
S. M. White ◽  
R. A. Hock-Mysliwiec ◽  
R. T. J. McAteer
Keyword(s):  
Emission Measure ◽  
Differential Emission Measure

A Twisted Flux Rope Model for Coronal Mass Ejections and Two-Ribbon Flares

2000 ◽  
Vol 529 (1) ◽  
pp. L49-L52 ◽  
Author(s):  
T. Amari ◽  
J. F. Luciani ◽  
Z. Mikic ◽  
J. Linker
Keyword(s):  
Coronal Mass Ejections ◽  
Flux Rope
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