scholarly journals Validation of a scaling law for the coronal magnetic field strength and loop length of solar and stellar flares

2016 ◽  
Vol 69 (1) ◽  
pp. 7 ◽  
Author(s):  
Kosuke Namekata ◽  
Takahito Sakaue ◽  
Kyoko Watanabe ◽  
Ayumi Asai ◽  
Kazunari Shibata
Keyword(s):  
Magnetic Field ◽  
Field Strength ◽  
Magnetic Field Strength ◽  
Scaling Law ◽  
Coronal Magnetic Field ◽  
Loop Length ◽  
Stellar Flares

scholarly journals Numerical Simulations of Solar Flares

2000 ◽  
Vol 195 ◽  
pp. 445-446
Author(s):  
T. Yokoyama ◽  
K. Shibata
Keyword(s):  
Magnetic Field ◽  
Field Strength ◽  
Heating Rate ◽  
Magnetic Field Strength ◽  
Mass Density ◽  
Scaling Law ◽  
Coronal Magnetic Field ◽  
Mhd Equations ◽  
Numerical Code ◽  
Volumetric Heating

We study reconnection and chromospheric evaporation in flares using a numerical code including nonlinear, anisotropic heat conduction (Yokoyama & Shibata 1998). The two-dimensional, nonlinear, time-dependent, resistive, compressible MHD equations are solved. The evolution from the rise phase to (the early part of) the decay phase of a solar flare is qualitatively reproduced in this simulation. Based on the results, we obtained a relationship between the flare temperature and the coronal magnetic field strength. We assume that the energy input to a loop balances with the conductive cooling rate, that the temperature at the loop apex is TA ≍ (2QL2/κ0)2/7, where Q is the volumetric heating rate, that L is the half-length of the loop, and that the Spitzer thermal conductivity constant is κ0 = 10−6 CGS. In our simulations, the heating mechanism is magnetic reconnection, so the heating rate is described as Q = B2/(4π) · Vin/L · l/sin Θ, where B is the coronal magnetic field strength, Vin is the inflow velocity (≍ 0.1 VA from our result and also from Petschek's theory), and Θ is the angle between the slow-mode MHD shock and the loop and is approximately given by sin Θ ≍ Vin/VA. By manipulating the equations, we find where ρ is the mass density of the corona. The simulation results show very good agreement with this scaling law.

scholarly journals Origin of Universal Correlation between Temperature and Emision Measure for Solar/Stellar Flares

2001 ◽  
Vol 203 ◽  
pp. 318-319
Author(s):  
K. Shibata ◽  
T. Yokoyama
Keyword(s):  
Magnetic Field ◽  
Field Strength ◽  
Heating Rate ◽  
Magnetic Field Strength ◽  
Mass Density ◽  
Scaling Law ◽  
Coronal Magnetic Field ◽  
Mhd Equations ◽  
Numerical Code ◽  
Volumetric Heating

We study the reconnection and the chromospheric evaporation in flares using the numerical code including nonlinear anisotropic heat conduction effect (Yokoyama & Shibata 1998; 2001). The two-dimensional, nonlinear, timedependent, resistive, compressible MHD equations are solved. The evolution from the rise phase to (the early part of) the decay phase of a solar flare is qualitatively reproduced in this simulation. Based on the results, we obtained a relationship between the flare temperature and the coronal magnetic field strength. If we assume that the input of energy to a loop balances with the conduction cooling rate, the temperature at the loop apex is TA ≈ (2QL2/κ0)2/7 where Q is the volumetric heating rate, L is the half-length of the loop, and κ0 = 10−6 eGS is the Spitzer's thermal conductivity constant. In our simulations, the heating mechanism is magnetic reconnection so that the heating rate is described as Q = B2/(4π) · Vin/L · 1/sin θ, where B is the coronal magnetic field strength, Vin is the inflow velocity (≈ 0.1VA from our result and also from Petschek's theory), and θ is the angle between the slow-mode MHD shock and the loop and is approximately given by sin θ ≈ Vin/VA. By manipulating the equations, we find where ρ is the mass density of the corona. The simulation results show very good agreement with this scaling law.

Dependence of Coronal Loop Temperature on Loop Length and Magnetic Field Strength

2018 ◽  
Vol 868 (2) ◽  
pp. 116 ◽  
Author(s):  
R. B. Dahlburg ◽  
G. Einaudi ◽  
I. Ugarte-Urra ◽  
A. F. Rappazzo ◽  
M. Velli
Keyword(s):  
Magnetic Field ◽  
Field Strength ◽  
Magnetic Field Strength ◽  
Coronal Loop ◽  
Loop Length

Coronal Magnetic Field Strength from Decameter Zebra-Pattern Observations: Complementarity with Band-Splitting Measurements of an Associated Type II Burst

Solar Physics ◽  
2014 ◽  
Vol 290 (1) ◽  
pp. 205-218 ◽  
Author(s):  
A. A. Stanislavsky ◽  
A. A. Konovalenko ◽  
A. A. Koval ◽  
V. V. Dorovskyy ◽  
P. Zarka ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Field Strength ◽  
Magnetic Field Strength ◽  
Coronal Magnetic Field ◽  
Type Ii ◽  
Zebra Pattern ◽  
Band Splitting

CONSTRAINING THE SOLAR CORONAL MAGNETIC FIELD STRENGTH USING SPLIT-BAND TYPE II RADIO BURST OBSERVATIONS

2016 ◽  
Vol 832 (1) ◽  
pp. 59 ◽  
Author(s):  
P. Kishore ◽  
R. Ramesh ◽  
K. Hariharan ◽  
C. Kathiravan ◽  
N. Gopalswamy
Keyword(s):  
Magnetic Field ◽  
Field Strength ◽  
Magnetic Field Strength ◽  
Radio Burst ◽  
Coronal Magnetic Field ◽  
Type Ii ◽  
Split Band ◽  
Band Type ◽  
Solar Coronal

Decay of the coronal magnetic field can release sufficient energy to power a solar flare

Science ◽  
2020 ◽  
Vol 367 (6475) ◽  
pp. 278-280 ◽  
Author(s):  
Gregory D. Fleishman ◽  
Dale E. Gary ◽  
Bin Chen ◽  
Natsuha Kuroda ◽  
Sijie Yu ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Particle Acceleration ◽  
Solar Flare ◽  
Field Strength ◽  
Magnetic Field Strength ◽  
Magnetic Energy ◽  
Strong Electric Field ◽  
Plasma Heating ◽  
Coronal Magnetic Field ◽  
Microwave Emission

Solar flares are powered by a rapid release of energy in the solar corona, thought to be produced by the decay of the coronal magnetic field strength. Direct quantitative measurements of the evolving magnetic field strength are required to test this. We report microwave observations of a solar flare, showing spatial and temporal changes in the coronal magnetic field. The field decays at a rate of ~5 Gauss per second for 2 minutes, as measured within a flare subvolume of ~1028 cubic centimeters. This fast rate of decay implies a sufficiently strong electric field to account for the particle acceleration that produces the microwave emission. The decrease in stored magnetic energy is enough to power the solar flare, including the associated eruption, particle acceleration, and plasma heating.

scholarly journals Radial distributions of magnetic field strength in the solar corona as derived from data on fast halo CMEs

2018 ◽  
Vol 4 (1) ◽  
pp. 3-11
Author(s):  
Виктор Файнштейн ◽  
Victor Fainshtein ◽  
Ярослав Егоров ◽  
Yaroslav Egorov
Keyword(s):  
Magnetic Field ◽  
Field Strength ◽  
Solar Corona ◽  
Magnetic Field Strength ◽  
Coronal Magnetic Field ◽  
The Body ◽  
Cone Model ◽  
Radial Profiles ◽  
Halo Cmes ◽  
Slow Wind

In recent years, information about the distance between the body of rapid coronal mass ejection (CME) and the associated shock wave has been used to measure the magnetic field in the solar corona. In all cases, this tech-nique allows us to find coronal magnetic field radial profiles B(R) applied to the directions almost perpendicular to the line of sight. We have determined radial distributions of magnetic field strength along the directions close to the Sun–Earth axis. For this purpose, using the “ice-cream cone” model and SOHO/LASCO data, we found 3D characteristics for fast halo coronal mass ejections (HCMEs) and for HCME-related shocks. With these data we managed to obtain the B(R) distributions as far as ≈43 solar radii from the Sun’s center, which is approximately twice as far as those in other studies based on LASCO data. We have concluded that to improve the accuracy of this method for finding the coronal magnetic field we should develop a technique for detecting CME sites moving in the slow and fast solar wind. We propose a technique for selecting CMEs whose central (paraxial) part actually moves in the slow wind.

scholarly journals A New Precise Measurement of the Coronal Magnetic Field Strength

2000 ◽  
Vol 541 (2) ◽  
pp. L83-L86 ◽  
Author(s):  
Haosheng Lin ◽  
Matthew J. Penn ◽  
Steven Tomczyk
Keyword(s):  
Magnetic Field ◽  
Field Strength ◽  
Magnetic Field Strength ◽  
Precise Measurement ◽  
Coronal Magnetic Field
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