Numerical simulations of driven MHD waves in coronal loops

Solar Physics ◽  
1996 ◽  
Vol 167 (1-2) ◽  
pp. 181-202 ◽  
Author(s):  
S. Parhi ◽  
P. De Bruyne ◽  
K. Murawski ◽  
M. Goossens ◽  
C. R. Devore
Keyword(s):  
Numerical Simulations ◽  
Mhd Waves ◽  
Coronal Loops

scholarly journals Energetics of magnetic transients in a solar active region plage

2019 ◽  
Vol 623 ◽  
pp. A176 ◽  
Author(s):  
L. P. Chitta ◽  
A. R. C. Sukarmadji ◽  
L. Rouppe van der Voort ◽  
H. Peter
Keyword(s):  
Magnetic Field ◽  
Active Region ◽  
Magnetic Flux ◽  
Numerical Simulations ◽  
Extreme Ultraviolet ◽  
Spatial Scales ◽  
Coronal Loops ◽  
The Sun ◽  
Flux Emergence ◽  
Transient Events

Context. Densely packed coronal loops are rooted in photospheric plages in the vicinity of active regions on the Sun. The photospheric magnetic features underlying these plage areas are patches of mostly unidirectional magnetic field extending several arcsec on the solar surface. Aims. We aim to explore the transient nature of the magnetic field, its mixed-polarity characteristics, and the associated energetics in the active region plage using high spatial resolution observations and numerical simulations. Methods. We used photospheric Fe I 6173 Å spectropolarimetric observations of a decaying active region obtained from the Swedish 1-m Solar Telescope (SST). These data were inverted to retrieve the photospheric magnetic field underlying the plage as identified in the extreme-ultraviolet emission maps obtained from the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory (SDO). To obtain better insight into the evolution of extended unidirectional magnetic field patches on the Sun, we performed 3D radiation magnetohydrodynamic simulations of magnetoconvection using the MURaM code. Results. The observations show transient magnetic flux emergence and cancellation events within the extended predominantly unipolar patch on timescales of a few 100 s and on spatial scales comparable to granules. These transient events occur at the footpoints of active region plage loops. In one case the coronal response at the footpoints of these loops is clearly associated with the underlying transient. The numerical simulations also reveal similar magnetic flux emergence and cancellation events that extend to even smaller spatial and temporal scales. Individual simulated transient events transfer an energy flux in excess of 1 MW m−2 through the photosphere. Conclusions. We suggest that the magnetic transients could play an important role in the energetics of active region plage. Both in observations and simulations, the opposite-polarity magnetic field brought up by transient flux emergence cancels with the surrounding plage field. Magnetic reconnection associated with such transient events likely conduits magnetic energy to power the overlying chromosphere and coronal loops.

Numerical simulations of fast MHD waves in a coronal plasma

Solar Physics ◽  
1993 ◽  
Vol 144 (2) ◽  
pp. 255-266 ◽  
Author(s):  
K. Murawski ◽  
B. Roberts
Keyword(s):  
Numerical Simulations ◽  
Coronal Plasma ◽  
Mhd Waves

scholarly journals The Distinction Between Thermal Nonequilibrium and Thermal Instability

Solar Physics ◽  
2019 ◽  
Vol 294 (12) ◽  
Author(s):  
James A. Klimchuk
Keyword(s):  
Large Amplitude ◽  
Thermal Instability ◽  
Mhd Waves ◽  
Accelerated Cooling ◽  
Coronal Loops ◽  
Thermal Nonequilibrium ◽  
Cold Condensation

AbstractFor some forms of steady heating, coronal loops are in a state of thermal nonequilibrium and evolve in a manner that includes accelerated cooling, often resulting in the formation of a cold condensation. This is frequently confused with thermal instability, but the two are in fact fundamentally different. We explain the distinction and discuss situations where they may be interconnected. Large-amplitude perturbations, perhaps associated with MHD waves, likely play a role in explaining phenomena that have been attributed to thermal nonequilibrium but also seem to require cross-field communication.

Heating of coronal loops by fast mode MHD waves

Solar Physics ◽  
1979 ◽  
Vol 64 (2) ◽  
pp. 287-301 ◽  
Author(s):  
Shadia Rifai Habbal ◽  
Egil Leer ◽  
Thomas E. Holzer
Keyword(s):  
Mhd Waves ◽  
Coronal Loops ◽  
Fast Mode

Nonlinear development of MHD waves in coronal loops

1997 ◽  
Vol 19 (12) ◽  
pp. 1891-1894 ◽  
Author(s):  
S. Parhi ◽  
B.P. Pandey ◽  
M. Goossens ◽  
G.S. Lakhina ◽  
P. De Bruyne
Keyword(s):  
Mhd Waves ◽  
Coronal Loops ◽  
Nonlinear Development

scholarly journals An Observational Test for Coronal Heating Models

2004 ◽  
Vol 219 ◽  
pp. 473-477
Author(s):  
Lidia van Driel-Gesztelyi ◽  
Pascal Démoulin ◽  
Cristina H. Mandrini ◽  
Louise K. Harra ◽  
James A. Klimchuk
Keyword(s):  
Magnetic Flux ◽  
Flux Density ◽  
Scaling Laws ◽  
Emission Measure ◽  
Coronal Heating ◽  
Mhd Waves ◽  
Magnetic Flux Density ◽  
Coronal Loops ◽  
Coronal Emission ◽  
The Mean

We correlate the evolution of the mean X-ray flux, emission measure and temperature (Yohkoh SXT & BCS) with the magnetic flux density (SOHO/MDI) in active region NOAA 7978 from its birth throughout its decay, for five solar rotations. We show that these plasma parameters together with other quantities deduced from them, such as the density and the pressure, follow power-law relationships with the mean magnetic flux density (B). We derive the dependence of the mean coronal heating rate on the magnetic flux density. We use the obtained scaling laws of coronal loops in thermal equilibrium to derive observational estimates of the scaling of the coronal heating with B. These results are used to test the validity of coronal heating models. We find that models based on the dissipation of stressed, current-carrying magnetic fields are in better agreement with the observations than models that attribute coronal heating to the dissipation of MHD waves injected at the base of the corona. This confirms, with smaller error bars, previous results obtained for individual coronal loops, as well as for the global coronal emission of the Sun and cool stars.

Heating of Coronal Loops by Fast-Mode MHD-Waves

1979 ◽  
Vol 44 ◽  
pp. 228-231
Author(s):  
S.R. Habbal ◽  
T.E. Holzer ◽  
E. Leer
Keyword(s):  
Solar Radius ◽  
Mhd Waves ◽  
Coronal Loops ◽  
X Rays ◽  
Fast Mode

Loops in the corona, ranging in size from a few hundredths of a solar radius to a few tenths are observed in X-rays and EUV (Vaiana et al., 1976; Levine and Withbroe, 1977). Their temperatures are in the 2 to 3 million degree range and the densities vary from 108to 1010cm-3(Foukal, 1975; Krieger, 1977).

Sign in / Sign up

Export Citation Format

Share Document