scholarly journals ANOMALOUS COOLING OF CORONAL LOOPS WITH TURBULENT SUPPRESSION OF THERMAL CONDUCTION

2016 ◽  
Vol 833 (1) ◽  
pp. 76 ◽  
Author(s):  
Nicolas H. Bian ◽  
Jonathan M. Watters ◽  
Eduard P. Kontar ◽  
A. Gordon Emslie
Keyword(s):  
Thermal Conduction ◽  
Coronal Loops

scholarly journals Thermal conduction effects on the kink instability in coronal loops

2010 ◽  
Vol 525 ◽  
pp. A96 ◽  
Author(s):  
G. J. J. Botha ◽  
T. D. Arber ◽  
A. W. Hood
Keyword(s):  
Thermal Conduction ◽  
Coronal Loops ◽  
Kink Instability

scholarly journals Damping of standing slow waves in hot coronal loops

2007 ◽  
Vol 3 (S247) ◽  
pp. 303-311
Author(s):  
Leonardo Di G. Sigalotti ◽  
César A. Mendoza-Briceño ◽  
Marialejandra Luna-Cardozo
Keyword(s):  
Energy Dissipation ◽  
Viscous Dissipation ◽  
Thermal Conduction ◽  
Slow Waves ◽  
Coronal Loops ◽  
Slow Mode ◽  
Decay Times ◽  
Crossing Time ◽  
Linear Limit ◽  
Radiative Losses

AbstractThe damping of standing slow mode oscillations in hot (T > 6 MK) coronal loops is described in the linear limit. The effects of energy dissipation by thermal conduction, viscosity, and radiative losses and gains are examined for both stratified and nonstratified loops. We find that thermal conduction acts on the way of increasing the period of the oscillations over the sound crossing time, whereas the decay times are mostly determined by viscous dissipation. Thermal conduction alone results in slower damping of the density and velocity waves compared to the observations. Only when viscosity is added do these waves damp out at the same rate of the observed SUMER loop oscillations. In the linear limit, the periods and decay times are barely affected by gravity.

scholarly journals Mechanisms for Coronal Mass Supply by Evaporative Micro-Events

2001 ◽  
Vol 203 ◽  
pp. 498-500
Author(s):  
J. C. Brown ◽  
S. Krucker ◽  
M. Güdel ◽  
A. O. Benz
Keyword(s):  
Solar Corona ◽  
Energy Release ◽  
Thermal Conduction ◽  
Major Part ◽  
Coronal Loops ◽  
Transport Mechanisms ◽  
Chromospheric Evaporation

There is extensive evidence from SoHO and other data that “micro-events” play an important role in sustaining at least some components of the solar corona. These are often termed coronal micro-” heating events” though a major part of their role is feeding coronal loops through chromospheric evaporation. We consider what can be learnt from these data concerning the energy release and transport mechanisms driving the evaporation, including thermal conduction and fast particles. We conclude, from one large event and the statistics of many small ones, that conductive evaporation alone does not fit observations and that fast particles or some other nonthermal driver must be involved.

scholarly journals Thermally damped linear compressional waves in a 2D solar coronal model

2007 ◽  
Vol 3 (S247) ◽  
pp. 320-323
Author(s):  
A. Marcu ◽  
I. Ballai ◽  
B. Orza
Keyword(s):  
Thermal Conduction ◽  
Transport Coefficients ◽  
Coronal Loops ◽  
Two Dimensional ◽  
Compressional Waves ◽  
Transversal Motion ◽  
Main Effects ◽  
The Waves ◽  
2D Model ◽  
Coronal Structures

AbstractThe high resolution observations (TRACE and SOHO) of waves in coronal structures have revealed a rapid damping of modes, sometimes their damping length being of the same order as their wavelength. The rapid damping of modes in coronal loops permits us to derive values for magnetic field and transport coefficients. In this contribution we study the damping of linear compressional waves considering a two-dimensional propagation in gravitationally stratified plasma in the presence of thermal conduction. By considering this 2D model, we show that the presence of an additional transversal motion has an important effect on the damping of the waves. This theoretical model allows as to conclude that the main effects influencing the damping of the waves are the degree of the transversal structuring and temperature.

Thermal conduction and modeling of static stellar coronal loops

Solar Physics ◽  
1993 ◽  
Vol 145 (1) ◽  
pp. 45-63 ◽  
Author(s):  
A. Ciaravella ◽  
G. Peres ◽  
S. Serio
Keyword(s):  
Thermal Conduction ◽  
Coronal Loops

Propagating magnetohydrodynamics waves in coronal loops

2005 ◽  
Vol 364 (1839) ◽  
pp. 461-472 ◽  
Author(s):  
I De Moortel
Keyword(s):  
Theoretical Model ◽  
Wavelet Analysis ◽  
Transition Region ◽  
Strong Correlation ◽  
Thermal Conduction ◽  
Active Regions ◽  
Coronal Loops ◽  
Two Dimensional ◽  
Magnetoacoustic Waves ◽  
High Cadence

High cadence Transition Region and Coronal Explorer (TRACE) observations show that outward propagating intensity disturbances are a common feature in large, quiescent coronal loops, close to active regions. An overview is given of measured parameters of such longitudinal oscillations in coronal loops. The observed oscillations are interpreted as propagating slow magnetoacoustic waves and are unlikely to be flare-driven. A strong correlation, between the loop position and the periodicity of the oscillations, provides evidence that the underlying oscillations can propagate through the transition region and into the corona. Both a one- and a two-dimensional theoretical model of slow magnetoacoustic waves are presented to explain the very short observed damping lengths. The results of these numerical simulations are compared with the TRACE observations and show that a combination of the area divergence and thermal conduction agrees well with the observed amplitude decay. Additionally, the usefulness of wavelet analysis is discussed, showing that care has to be taken when interpreting the results of wavelet analysis, and a good knowledge of all possible factors that might influence or distort the results is a necessity.

scholarly journals Damping of non-isothermal hot coronal loops oscillations

2007 ◽  
Vol 3 (S247) ◽  
pp. 316-319
Author(s):  
M. Luna-Cardozo ◽  
R. Erdélyi ◽  
César A. Mendoza-Briceño
Keyword(s):  
Coronal Loop ◽  
Thermal Conduction ◽  
Numerical Experiments ◽  
Initial Temperature ◽  
Standing Waves ◽  
Coronal Loops ◽  
Governing Equations ◽  
Longitudinal Waves ◽  
Decay Times ◽  
Range Of Values

AbstractHere we investigate longitudinal waves in non-isothermal hot (T ≥ 5.0 MK) coronal loops. Motivated by SOHO SUMER and Yohkoh SXT observations and taking into account gravitational stratification, thermal conduction, compressive viscosity, radiative cooling, and heating, the governing equations of 1D hydrodynamics is solved numerically for standing wave oscillations along a magnetic field line. A semicircular shape is chosen to represent a coronal loop. It was found that the decay time of standing waves decreases with the increase of the initial temperature and the periods of oscillations are affected by the different initial velocities and loop lengths studied by the numerical experiments. The predicted decay times are within the range of values inferred from Doppler-shift oscillations observed by SUMER in hot coronal loops.

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