Microwave burst spectra and solar flare magnetic fields

Solar Physics ◽  
1977 ◽  
Vol 54 (1) ◽  
pp. 165-168 ◽  
Author(s):  
Donald F. Neidig
Keyword(s):  
Magnetic Fields ◽  
Solar Flare ◽  
Microwave Burst

scholarly journals Simultaneously Observational Study of Filtergrams, Velocity and Vector Magnetic Fields for a Solar Flare on 7 Oct. 1987

1989 ◽  
Vol 104 (2) ◽  
pp. 215-218
Author(s):  
Lin Yuanzhang ◽  
Zhang Hongqi ◽  
Han Feng ◽  
Liu Kening
Keyword(s):  
Active Region ◽  
Magnetic Fields ◽  
Solar Flare ◽  
Observational Study ◽  
Astronomical Observatory ◽  
Solar Telescope ◽  
Active Region Noaa ◽  
Vector Magnetograms ◽  
Region Noaa

AbstractIn this paper are described the simultaneously observational results of filtergrams, Dopplergrams and vector magnetograms for a solar flare in the active region NOAA/USAF -1862 on 7 Oct. 1987 with the solar telescope-magnctograph of Beijing Astronomical Observatory. From the analyses of these data, some conclusions were obtained.

scholarly journals The Evolution of Sunspot Magnetic Fields Associated with a Solar Flare

Solar Physics ◽  
2011 ◽  
Vol 277 (1) ◽  
pp. 45-57 ◽  
Author(s):  
Sophie A. Murray ◽  
D. Shaun Bloomfield ◽  
Peter T. Gallagher
Keyword(s):  
Magnetic Fields ◽  
Solar Flare

scholarly journals Measurements of local magnetic fields in a solar flare by splitting of emissive peaks in cores of spectral lines

2018 ◽  
pp. 47-52 ◽  
Author(s):  
V. Lozitsky
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Solar Flare ◽  
Filling Factor ◽  
Spectral Lines ◽  
Local Fields ◽  
Strong Component ◽  
Component Structure ◽  
Local Magnetic Fields ◽  
The Magnetic Field

We present study of solar flare of 19 July 2000 which arose in active region NOAA 9087 and had M 5.6 / 3N importance. Observational material was obtained with the Echelle spectrograph of the horizontal solar telescope of the Astronomical Observatory of Taras Shevchenko National University of Kyiv. The local magnetic fields in this flare were measured by the splitting of emissive peaks of the FeI 5269.54, FeII 4923.93, Нα, Нβ, Нγand D3 HeI lines. The basic idea of the method is based on the fact that the flare emission in some spectral lines is clearly divided into two components: (1) wider and unpolarized, and (2) more narrow and polarized, with significant Zeeman splitting. This is indication to the two-component structure of the magnetic field, with substantially different magnetic fields and thermodynamical conditions in these two components. Due to the fact that the polarized emission is quite confidently separated from the unpolarized, it is possible to measure the local magnetic fields directly in the second (strong) component regardless of the filling factor. It was found that in the bright place of this flare, which was projected on the sunspot penumbra, the effective magnetic field Beff in the FeI 6301.5 i 6302.5 lines measured by splitting of the Fraunhofer profiles, was 900 G. However, the splitting of emissive peaks in Нα, Нβ, Нγ and D3 lines corresponds to 1000 G, 1400 G, 1450 G and about zero, respectively, with errors of 30-50 G for abovenamed FeI lines and about 100–150 G for other lines. This difference in the results is probably due to the fact that in the case of FeI 6301.5 i 6302.5 lines, the Beff value represents several parameters, including the value of the background field, the filling factor, and the intensity of the local fields in the strong component. In contrast, data on the Нα, Нβ, Нγ, and D3 lines mainly reflect local fields in the strong component and indicate the nonmonotonous distribution of the magnetic field with height in solar atmosphere, with its maximum at the chromospheric level. Earlier in this flare, when constructing its semi-empirical model, local amplification of the magnetic field at the photospheric level was discovered, and its value reached 1500 G. These data are confirmed by direct measurements of splitting of emissive peaks in FeI 5269.54 and FeII 4923.93 lines, according to which the magnetic field in the flare was 1250 ± 100 G. Thus, in this flare there were at least two regions (possibly two flat layers) of local amplification of the magnetic field.

scholarly journals On the Thermalisation of Flare-Time Energetic Electrons Observed at Radio and X-Ray Wavelengths

1980 ◽  
Vol 91 ◽  
pp. 223-226
Author(s):  
S. S. Degaonkar ◽  
H. S. Sawant ◽  
R. V. Bhonsle
Keyword(s):  
Solar Flare ◽  
Energetic Electrons ◽  
Gradual Rise ◽  
X Ray ◽  
Slow Decay ◽  
Microwave Burst ◽  
Long Duration ◽  
Microwave Bursts

An interesting microwave event at 2800 MHz was recorded at Ahmedabad on September 19, 1977 at 1026 UT at the same time as the H-Alpha solar flare of importance 3B. The microwave burst was of impulsive nature, with as many as twenty impulses in seventy minutes with a quasi-periodicity of 1 to 5 minutes. An X-ray burst recorded by GOES Satellite in 1-8A band showed at the same time a smooth soft X-ray profile with apparently no sign of hard X-ray bursts. This indicates that the acceleration of discrete electron streams which produced impulsive microwave bursts was not sufficient to produce the hard X-ray component but got thermalised to produce soft X-ray emission, with a gradual rise and a slow decay covering a long duration of more than 2 1/2 hours.

scholarly journals Transient rotation of photospheric vector magnetic fields associated with a solar flare

2018 ◽  
Vol 9 (1) ◽  
Author(s):  
Yan Xu ◽  
Wenda Cao ◽  
Kwangsu Ahn ◽  
Ju Jing ◽  
Chang Liu ◽  
...  
Keyword(s):  
Magnetic Fields ◽  
Solar Flare

scholarly journals Microwave burst with fine spectral structures in a solar flare on 2011 August 9

2012 ◽  
Vol 55 ◽  
pp. 251-255
Author(s):  
B.L. Tan ◽  
C.M. Tan ◽  
Y.Y. Liu
Keyword(s):  
Solar Flare ◽  
Microwave Burst
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