By use of the high-resolution spectral data obtained with THEMIS on 2002 September 5, the spectra and characteristics of five well-observed microflares have been analyzed. Our results indicate that some of them are lo...By use of the high-resolution spectral data obtained with THEMIS on 2002 September 5, the spectra and characteristics of five well-observed microflares have been analyzed. Our results indicate that some of them are located near the longitudinal magnetic polarity inversion lines. All the microflares are accompanied by mass motions. The most obvious characteristic of the Hα microflare spectra is the emission at the center of both Hα and CaⅡ 8542A lines. For the first time both thermal and non-thermal semi-empirical atmospheric models for the conspicuous and faint microflares are computed. In computing the non-thermal models, we assume that the electron beam resulting from magnetic reconnection is produced in the chromosphere, because it requires lower energies for the injected particles. It is found there is obvious heating in the low chromosphere. The temperature enhancement is about 1000-2200 K in the thermal models. If the non-thermal effects are included, then the required temperature increase can be reduced by 100-150 K. These imply that the Hα microflares can probably be produced by magnetic reconnection in the solar lower atmosphere. The radiative and kinetic energies of the Hα microflares are estimated and the total energy is found to be 10^27 - 4× 10^28 erg.展开更多
A very rare type of solar radio microflares occurred during 0645～0720 UT on Jan. 5, 1994 is introduced in this paper. The radio and optical characteristics of the solar microflares of a short decimetric wave (1 42 GH...A very rare type of solar radio microflares occurred during 0645～0720 UT on Jan. 5, 1994 is introduced in this paper. The radio and optical characteristics of the solar microflares of a short decimetric wave (1 42 GHz) are discussed. This event contains 53 radio fast fine structures (FFS), that is, 53 intermittently periodic impulse trains with similar morphologies superimposed on the continuum radiation background. The intensities of the pulses lie within 150～200 s. f. u. and the durations (half power width) are of the order of 10～50 milliseconds (ms). 18 out of 53 FFSs are doublepeak-separating structures. In this paper we try to discuss the generation mechanism qualitatively and find it is in consistence with the model of current loop explosive coalescence (Sakai and De Jager, 1989a, 1989b): the explosive coalescence of the multiple of cross magnetic flux loops causes the plasma disturbance and so rapidly transform the magnetic energy into the kinetic energy of electrons.展开更多
基金Supported by the National Natural Science Foundation of China.
文摘By use of the high-resolution spectral data obtained with THEMIS on 2002 September 5, the spectra and characteristics of five well-observed microflares have been analyzed. Our results indicate that some of them are located near the longitudinal magnetic polarity inversion lines. All the microflares are accompanied by mass motions. The most obvious characteristic of the Hα microflare spectra is the emission at the center of both Hα and CaⅡ 8542A lines. For the first time both thermal and non-thermal semi-empirical atmospheric models for the conspicuous and faint microflares are computed. In computing the non-thermal models, we assume that the electron beam resulting from magnetic reconnection is produced in the chromosphere, because it requires lower energies for the injected particles. It is found there is obvious heating in the low chromosphere. The temperature enhancement is about 1000-2200 K in the thermal models. If the non-thermal effects are included, then the required temperature increase can be reduced by 100-150 K. These imply that the Hα microflares can probably be produced by magnetic reconnection in the solar lower atmosphere. The radiative and kinetic energies of the Hα microflares are estimated and the total energy is found to be 10^27 - 4× 10^28 erg.
文摘A very rare type of solar radio microflares occurred during 0645～0720 UT on Jan. 5, 1994 is introduced in this paper. The radio and optical characteristics of the solar microflares of a short decimetric wave (1 42 GHz) are discussed. This event contains 53 radio fast fine structures (FFS), that is, 53 intermittently periodic impulse trains with similar morphologies superimposed on the continuum radiation background. The intensities of the pulses lie within 150～200 s. f. u. and the durations (half power width) are of the order of 10～50 milliseconds (ms). 18 out of 53 FFSs are doublepeak-separating structures. In this paper we try to discuss the generation mechanism qualitatively and find it is in consistence with the model of current loop explosive coalescence (Sakai and De Jager, 1989a, 1989b): the explosive coalescence of the multiple of cross magnetic flux loops causes the plasma disturbance and so rapidly transform the magnetic energy into the kinetic energy of electrons.
