Calculations of Soft X-ray Images from MHD Simulations of Heating of Coronal Loops

1996 ◽  
pp. 423-424
Author(s):  
A. J. C. Belién ◽  
S. Poedts ◽  
J. P. Goedbloed
Keyword(s):  
Coronal Loops ◽  
X Ray ◽  
Mhd Simulations

scholarly journals Can Multi-threaded Flux Tubes in Coronal Arcades Support a Magnetohydrodynamic Avalanche?

Solar Physics ◽  
2021 ◽  
Vol 296 (8) ◽  
Author(s):  
J. Threlfall ◽  
J. Reid ◽  
A. W. Hood
Keyword(s):  
Magnetic Fields ◽  
Three Dimensional ◽  
Coronal Loops ◽  
Flux Tubes ◽  
Single Thread ◽  
Mhd Instabilities ◽  
Mhd Instability ◽  
Mhd Simulations ◽  
Ideal Mhd ◽  
Model Geometry

AbstractMagnetohydrodynamic (MHD) instabilities allow energy to be released from stressed magnetic fields, commonly modelled in cylindrical flux tubes linking parallel planes, but, more recently, also in curved arcades containing flux tubes with both footpoints in the same photospheric plane. Uncurved cylindrical flux tubes containing multiple individual threads have been shown to be capable of sustaining an MHD avalanche, whereby a single unstable thread can destabilise many. We examine the properties of multi-threaded coronal loops, wherein each thread is created by photospheric driving in a realistic, curved coronal arcade structure (with both footpoints of each thread in the same plane). We use three-dimensional MHD simulations to study the evolution of single- and multi-threaded coronal loops, which become unstable and reconnect, while varying the driving velocity of individual threads. Experiments containing a single thread destabilise in a manner indicative of an ideal MHD instability and consistent with previous examples in the literature. The introduction of additional threads modifies this picture, with aspects of the model geometry and relative driving speeds of individual threads affecting the ability of any thread to destabilise others. In both single- and multi-threaded cases, continuous driving of the remnants of disrupted threads produces secondary, aperiodic bursts of energetic release.

Three-dimensional MHD simulations of X-ray emitting subcluster plasmas in cluster of galaxies

2005 ◽  
Vol 36 (4) ◽  
pp. 636-642 ◽  
Author(s):  
N. Asai ◽  
N. Fukuda ◽  
R. Matsumoto
Keyword(s):  
Three Dimensional ◽  
X Ray ◽  
Cluster Of Galaxies ◽  
Mhd Simulations

scholarly journals Observed effects of star-planet interaction

2015 ◽  
Vol 11 (S320) ◽  
pp. 382-387
Author(s):  
Scott J. Wolk ◽  
Ignazio Pillitteri ◽  
Katja Poppenhaeger
Keyword(s):  
Magnetic Interaction ◽  
Phase Lag ◽  
Significant Activity ◽  
X Rays ◽  
Stellar Activity ◽  
X Ray ◽  
Hot Jupiters ◽  
Mhd Simulations ◽  
Magnetic Origin ◽  
Host Stars

AbstractSince soon after the discovery of hot Jupiters, it had been suspected that interaction of these massive bodies with their host stars could give rise to observable signals. We discuss the observational evidence for star-planet interactions (SPI) of tidal and magnetic origin observed in X-rays and FUV. Hot Jupiters can significantly impact the activity of their host stars through tidal and magnetic interaction, leading to either increased or decreased stellar activity – depending on the internal structure of the host star and the properties of the hosted planet. In HD 189733, X-ray and FUV flares are preferentially in a very restricted range of planetary phases. Matsakos et al. (2015) show, using MHD simulations, planetary gas can be liberated, forming a stream of material that gets compressed and accretes onto the star with a phase lag of 70-90 degrees. This scenario explains many features observed both in X-rays and the FUV (Pillitteri et al. 2015). On the other hand, WASP-18 – an F6 star with a massive hot Jupiter, shows no signs of activity in X-rays or UV. Several age indicators (isochrone fitting, Li abundance) point to a young age (~0.5 –1.0 Gyr) and thus significant activity was expected. In this system, tidal SPI between the star and the very close-in and massive planet appears to destroy the formation of magnetic dynamo and thus nullify the stellar activity.

The Skew of X-Ray Coronal Loops Overlying Hα Filaments

1996 ◽  
pp. 497-498 ◽  
Author(s):  
S. F. Martin ◽  
A. H. Mcallister
Keyword(s):  
Coronal Loops ◽  
X Ray

scholarly journals X-Ray Flares and Outflows Driven by Magnetic Interaction Between a Protostar and its Surrounding Disk

1997 ◽  
Vol 163 ◽  
pp. 717-718
Author(s):  
Mitsuru Hayashi ◽  
Kazunari Shibata ◽  
Ryoji Matsumoto
Keyword(s):  
Magnetic Field ◽  
Current Sheet ◽  
Plasma Temperature ◽  
Magnetic Interaction ◽  
Central Star ◽  
X Ray ◽  
Mhd Simulations ◽  
Flare Loops ◽  
Hot Plasma ◽  
Dipole Magnetic Field

AbstractHere we present a model of hard X-ray flares and hot plasma outflows (optical jets) observed in protostars. Assuming that the dipole magnetic field of a protostar threads the protostellar disk, we carried out 2.5-dimensional magnetohydrodynamic (MHD) simulations of the diskstar interaction. The closed magnetic loops connecting the central star and the disk are twisted by the rotation of the disk. In the presence of resistivity, magnetic reconnection takes place in the current sheet formed inside the expanding loops. Hot, outgoing plasmoid and post flare loops are formed as a result of the reconnection. Numerical results are consistent with the observed plasma temperature (107 – 108K), the length of the flaring loop (1011 – 1012cm), and the speed of optical jets (200 – 400 km s−1 ).

scholarly journals Self-organized braiding in solar coronal loops

2015 ◽  
Vol 81 (4) ◽  
Author(s):  
M. A. Berger ◽  
M. Asgari-Targhi ◽  
E. E. DeLuca
Keyword(s):  
Coronal Loops ◽  
Frequency Distributions ◽  
Fire Model ◽  
X Ray ◽  
Self Organized ◽  
Forest Fire Model ◽  
Distribution Laws ◽  
Field Lines ◽  
Power Law Distributions ◽  
Solar Coronal

AbstractIn this paper, we investigate the evolution of braided solar coronal loops. We assume that coronal loops consist of several internal strands which twist and braid about each other. Reconnection between the strands leads to small flares and heating of the loop to x-ray temperatures. Using a method of generating and releasing braid structure similar to a forest fire model, we show that the reconnected field lines evolve to a self-organised critical state. In this state, the frequency distributions of coherent braid sequences as well as flare energies follow power law distributions. We demonstrate how the presence of net helicity in the loop alters the distribution laws.

Visualization of resonant absorption in solar coronal loops by simulation of soft x-ray images

1996 ◽  
Vol 10 (6) ◽  
pp. 573 ◽  
Author(s):  
A. J. C. Beliën ◽  
S. Poedts ◽  
H. J. W. Spoelder ◽  
R. Leenders ◽  
J. P. Goedbloed
Keyword(s):  
Resonant Absorption ◽  
Coronal Loops ◽  
X Ray ◽  
Solar Coronal

scholarly journals A Study of the Decay Phase of an X-Ray Flare on Algol

1989 ◽  
Vol 104 (2) ◽  
pp. 123-126
Author(s):  
R. Mewe ◽  
G.H.J. van den Oord ◽  
J. Jakimiec
Keyword(s):  
Decay Time ◽  
Scaling Laws ◽  
Decay Phase ◽  
Coronal Loops ◽  
Unique Determination ◽  
X Ray ◽  
Additional Heating ◽  
Loop Volume ◽  
The Common

AbstractWe have re-analyzed the X-ray flare on Algol which was observed with EXOSAT (White et al. (1986)). The common practice of estimating loop volume and length from the decay time of the flare is discussed extensively. We show that during the decay phase of the flare both scaling laws for coronal loops are valid. This implies a unique determination of loop volume and length and allows a check whether additional heating occurs in the decay phase of a flare.

scholarly journals Long-term stability of the dead-zone in proto-planetary disks

2010 ◽  
Vol 6 (S276) ◽  
pp. 418-419
Author(s):  
Mario Flock ◽  
Neal Turner ◽  
Natalia Dzyurkevich ◽  
Hubert Klahr
Keyword(s):  
Dead Zone ◽  
Cosmic Ray ◽  
X Ray ◽  
Long Term Stability ◽  
Mhd Simulations ◽  
Magnetic Resistivity ◽  
Ideal Mhd ◽  
Self Consistent ◽  
Ionization Fraction

AbstractWe present 3D global non-ideal MHD simulations with a self consistent dynamic evolution of ionization fraction of the gas as result of reduced chemical network. We include X-ray ionization from the star as well as cosmic ray ionization. Based on local gas density and temperature in our chemical network, we determine the magnetic resistivity, which is fed back in MHD simulations. Parameters for dust size and abundance are chosen to have accreting layers and a laminar “dead” mid-plane.

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