Explorations of electric current system in solar active regions

Solar Physics ◽  
1987 ◽  
Vol 109 (2) ◽  
pp. 307-320 ◽  
Author(s):  
Y. J. Ding ◽  
M. J. Hagyard ◽  
A. C. Deloach ◽  
Q. F. Hong ◽  
X. P. Liu
Keyword(s):  
Electric Current ◽  
Current System ◽  
Active Regions ◽  
Solar Active Regions

Electric-current Neutralization and Eruptive Activity of Solar Active Regions

2020 ◽  
Author(s):  
Tibor Torok ◽  
Yang Liu ◽  
James E. Leake ◽  
Xudong Sun ◽  
Viacheslav S. Titov
Keyword(s):  
Electric Current ◽  
Active Regions ◽  
Total Current ◽  
Eruptive Activity ◽  
Physical Conditions ◽  
Limited Success ◽  
Solar Active Regions ◽  
Good Proxy ◽  
Mass Ejection ◽  
Magnetogram Data

<p>The physical conditions that determine the eruptive activity of solar active regions (ARs) are still not well understood. Various proxies for predicting eruptive activity have been suggested, with relatively limited success. Moreover, it is presently unclear under which conditions an eruption will remain confined to the low corona or produce a coronal mass ejection (CME).</p><p>Using vector magnetogram data from SDO/HMI, we investigate the association between electric-current neutralization and eruptive activity for a sample of ARs. We find that the vast majority of CME-producing ARs are characterized by a strongly non-neutralized total current, while the total current in ARs that do not produce CMEs is almost perfectly neutralized, even if those ARs produce strong (X-class) confined flares. This suggests that the degree of current neutralization can serve as a good proxy for assessing the ability of ARs to produce CMEs. </p><p> </p>

scholarly journals Electric-current Neutralization, Magnetic Shear, and Eruptive Activity in Solar Active Regions

2017 ◽  
Vol 846 (1) ◽  
pp. L6 ◽  
Author(s):  
Yang Liu ◽  
Xudong Sun ◽  
Tibor Török ◽  
Viacheslav S. Titov ◽  
James E. Leake
Keyword(s):  
Electric Current ◽  
Active Regions ◽  
Eruptive Activity ◽  
Magnetic Shear ◽  
Solar Active Regions

Radio Measurements of Coronal Magnetic Fields

1994 ◽  
Vol 144 ◽  
pp. 21-28 ◽  
Author(s):  
G. B. Gelfreikh
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Solar Corona ◽  
Active Regions ◽  
High Sensitivity ◽  
Coronal Magnetic Field ◽  
Transverse Magnetic ◽  
Radio Sources ◽  
Radio Waves ◽  
Solar Active Regions

AbstractA review of methods of measuring magnetic fields in the solar corona using spectral-polarization observations at microwaves with high spatial resolution is presented. The methods are based on the theory of thermal bremsstrahlung, thermal cyclotron emission, propagation of radio waves in quasi-transverse magnetic field and Faraday rotation of the plane of polarization. The most explicit program of measurements of magnetic fields in the atmosphere of solar active regions has been carried out using radio observations performed on the large reflector radio telescope of the Russian Academy of Sciences — RATAN-600. This proved possible due to good wavelength coverage, multichannel spectrographs observations and high sensitivity to polarization of the instrument. Besides direct measurements of the strength of the magnetic fields in some cases the peculiar parameters of radio sources, such as very steep spectra and high brightness temperatures provide some information on a very complicated local structure of the coronal magnetic field. Of special interest are the results found from combined RATAN-600 and large antennas of aperture synthesis (VLA and WSRT), the latter giving more detailed information on twodimensional structure of radio sources. The bulk of the data obtained allows us to investigate themagnetospheresof the solar active regions as the space in the solar corona where the structures and physical processes are controlled both by the photospheric/underphotospheric currents and surrounding “quiet” corona.

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