A large Type Ⅳμ solar radio burst was observed at Yunnan observatory on December 16, 1988. The burst was associated by a coronal mass ejection (CME) with the radio signature of Type Ⅱ and Type Ⅳ bursts. On the bas...A large Type Ⅳμ solar radio burst was observed at Yunnan observatory on December 16, 1988. The burst was associated by a coronal mass ejection (CME) with the radio signature of Type Ⅱ and Type Ⅳ bursts. On the basis of Beijing Huairou magnetogram of AR5278, power law distribution of electrons of the source region is calculated. It is suggested that the Type Ⅳμ burst associated with CME was due to the gyrosynchrotron radiation of high energy electrons trapped by magnetic field. Finally, some quantitative and qualitative explanations are proposed.展开更多
CMEs(Coronal Mass Ejections) are an important means of energy release in the solar corona.Solar Polar Orbit Radio Telescope(SPORT) is a mission being proposed for observing the propagation of interplanetary CMEs from ...CMEs(Coronal Mass Ejections) are an important means of energy release in the solar corona.Solar Polar Orbit Radio Telescope(SPORT) is a mission being proposed for observing the propagation of interplanetary CMEs from solar polar orbit.The main payload onboard SPORT is a synthetic aperture interferometric radiometer,which receives radio emission of interplanetary CMEs. It is identified that there are mainly three radio emission mechanisms of CMEs,i.e.,bremsstrahlung, gyrosynchrotron emission and plasma emission.Among these emission types,bremsstrahlung emission is the main emission mechanism of the high-density plasma clouds of interplanetary CMEs.Gyrosynchrotron emission is the continuous emission generated by high-energy electrons from CMEs, while plasma emission is the main mechanism of transient radio bursts from CMEs.In this paper,the gyrosynchrotron emission of interplanetary CMEs is focused on.Firstly,the mechanism of gyrosynchrotron emission is reviewed.Secondly,a review of the physical parameter models of background solar wind and interplanetary CMEs is presented.After these,the brightness temperature and polarization of gyrosynchrotron emission of interplanetary CMEs are calculated and analyzed.Finally, the detectability of gyrosynchrotron emission of interplanetary CMEs by radio meters is discussed briefly.展开更多
Formulae of gyrosychrotron radiation from nonthermal electrons have been developed, which can be applied to optical thick cases based on the work of Dulk, and a more precise formula of peak frequency has been derived ...Formulae of gyrosychrotron radiation from nonthermal electrons have been developed, which can be applied to optical thick cases based on the work of Dulk, and a more precise formula of peak frequency has been derived than that given by Dulk.展开更多
We have performed microwave diagnostics of the magnetic field strengths in solar flaring loops based on the theory of gyrosynchrotron emission.From Nobeyama Radioheliograph observations of three flare events at 17 and...We have performed microwave diagnostics of the magnetic field strengths in solar flaring loops based on the theory of gyrosynchrotron emission.From Nobeyama Radioheliograph observations of three flare events at 17 and 34 GHz,we obtained the degree of circular polarization and the spectral index of microwave flux density,which were then used to map the magnetic field strengths in post-flare loops.Our results show that the magnetic field strength typically decreases from ~800 G near the loop footpoints to~100 G at a height of 10-25 Mm.Comparison of our results with magnetic field modeling using a flux rope insertion method is also discussed.Our study demonstrates the potential of microwave imaging observations,even at only two frequencies,in diagnosing the coronal magnetic field of flaring regions.展开更多
文摘A large Type Ⅳμ solar radio burst was observed at Yunnan observatory on December 16, 1988. The burst was associated by a coronal mass ejection (CME) with the radio signature of Type Ⅱ and Type Ⅳ bursts. On the basis of Beijing Huairou magnetogram of AR5278, power law distribution of electrons of the source region is calculated. It is suggested that the Type Ⅳμ burst associated with CME was due to the gyrosynchrotron radiation of high energy electrons trapped by magnetic field. Finally, some quantitative and qualitative explanations are proposed.
基金Supported by the National Natural Science Foundation of China(No.40574070)China Post-doctor Foundation
文摘CMEs(Coronal Mass Ejections) are an important means of energy release in the solar corona.Solar Polar Orbit Radio Telescope(SPORT) is a mission being proposed for observing the propagation of interplanetary CMEs from solar polar orbit.The main payload onboard SPORT is a synthetic aperture interferometric radiometer,which receives radio emission of interplanetary CMEs. It is identified that there are mainly three radio emission mechanisms of CMEs,i.e.,bremsstrahlung, gyrosynchrotron emission and plasma emission.Among these emission types,bremsstrahlung emission is the main emission mechanism of the high-density plasma clouds of interplanetary CMEs.Gyrosynchrotron emission is the continuous emission generated by high-energy electrons from CMEs, while plasma emission is the main mechanism of transient radio bursts from CMEs.In this paper,the gyrosynchrotron emission of interplanetary CMEs is focused on.Firstly,the mechanism of gyrosynchrotron emission is reviewed.Secondly,a review of the physical parameter models of background solar wind and interplanetary CMEs is presented.After these,the brightness temperature and polarization of gyrosynchrotron emission of interplanetary CMEs are calculated and analyzed.Finally, the detectability of gyrosynchrotron emission of interplanetary CMEs by radio meters is discussed briefly.
文摘Formulae of gyrosychrotron radiation from nonthermal electrons have been developed, which can be applied to optical thick cases based on the work of Dulk, and a more precise formula of peak frequency has been derived than that given by Dulk.
基金supported by the Strategic Priority Research Program of Chinese Academy of Sciences (Grant No. XDA17040507)the National Natural Science Foundation of China (Grant Nos. 11790300, 11790301, 11790302, 11790304, 11825301, 11973057, 11803002 and 11473071)。
文摘We have performed microwave diagnostics of the magnetic field strengths in solar flaring loops based on the theory of gyrosynchrotron emission.From Nobeyama Radioheliograph observations of three flare events at 17 and 34 GHz,we obtained the degree of circular polarization and the spectral index of microwave flux density,which were then used to map the magnetic field strengths in post-flare loops.Our results show that the magnetic field strength typically decreases from ~800 G near the loop footpoints to~100 G at a height of 10-25 Mm.Comparison of our results with magnetic field modeling using a flux rope insertion method is also discussed.Our study demonstrates the potential of microwave imaging observations,even at only two frequencies,in diagnosing the coronal magnetic field of flaring regions.
