太阳射电微波爆发的频谱分析

A SPECTRAL ANALYSIS OF THE SOLAR RADIO MICROWAVE BURST ON 1 APRIL 1981

1981年4月1日太阳发生一个4N级Hα耀斑并伴随出现强烈的IV型射电爆发.本文对北京天文台,西澳大利亚站等射电资料进行分析.分析表明:(1)该事件的微波源状态相对稳定,米波源位置存在移动,因此产生微波辐射与米波辐射是两组不同的电子群体,在爆发频谱指数的时变曲线上表现出明显的形态差异.还由于两者辐射源的位置不同,微波与米波的爆发在峰值时刻上也不完全符合.(2)4月1日微波大爆发是由三个主爆发组成的,它们的峰值时刻分别为0135.1,0146.1,0153.6UT.由射电高频端谱指数算出的非热电子能谱指数表明,在射电爆发的三个峰值时刻电子能谱都变硬.本文还得出该活动区的非热电子平均速度(以光速c为单位)β为0.9左右,磁场强度B为430G.并由回旋同步辐射阻尼算得,非热电子的寿命为829秒,这个数值与三个主峰的持续时间相吻合.

A 4N Ha solar flare occurred on April 1, 1981, and accompanied with strong type IV radio burst. This paper analyses the radio data of the burst obtained at Beijing Observatory and Lear-month Observatory. The result shows that:1. The microwave source of the event is relatively stable, but the source at meter waves moves. There seems to be two electron populations responsible for microwave and meterwave radiations, respectively. The time difference between the microwave peaks and meterwave peaks is believed to be due to the different positions of the two kinds of sources.2. On April 1, 1981 the great microwave burst consists of three major bursts. The times of flux peaks are 0135.1 UT, 0146:1 UT and 0153.6 UT, respectively. The non-thermal electron spectral indices calculated at the high frequency end of the radio spectra show that the electron spectra become harder at peaks. For this burst, the calculated, average non-thermal electron speed is about 0.9c (c is light speed) and the magnetic field stre out 430G. Using the assumption of damping radiation of gyro-synchrotron, the calculated mean life of the non-thermal electrons is 829 second, which is consistent with the duration of the three major bursts.