太阳白光耀斑的射电辐射特征:运动Ⅳ型爆发和与耀斑后环共生的短周期脉动现象

CHARACTERISTICS OF RADIO EMISSION OF SOLAR WHITE LIGHT FLARES:MOVING TYPE IV BURSTS AND SHORT TERM PULSATIONS WITH ASSOCIATED POST FLARE LOOPS

通过１９９１ 年６ 月６ 日一个复杂的太阳活动事件（ 包括宽带射电运动Ⅳ型爆发、脉冲相伴生的白光耀斑、耀斑后环及其伴生的射电多重短周期（ 约１ － ４ 秒） 脉动现象等） 的分析，探讨了白光耀斑产生的射电辐射特征，根据太阳白光耀斑和射电运动Ⅳ型爆发产生的物理过程，着重讨论了射电运动Ⅳ型爆发、耀斑后环和短周期脉动现象。

The white light flares (WLFs) associated with radio moving type Ⅳ bursts and post flare loops and their accompanied radio short term pulsations are relatively rare.So far their relations have not been sufficiently investigated in literature.In this paper a complicated solar activity on June 6,1991 is analyzed.It includes a WLF in impulsive phase of flare (from Beijing Observatory),a moving type Ⅳ burst (from Yunnan Observatory) and multiple radio pulsations with periods of about 1-4s with a time resolution of 1 ms at two frequencies.The characteristics of radio emission associated with the WLF are studied. In particular,the moving type Ⅳ burst and radio short term pulsations in the post flare loops are discussed according to the physical processes of the WLF and radio moving type Ⅳ bursts,and it is suggested that they are the counterparts of the WLF.From the beginning times of the WLF and radio bursts we know that the origin of heating may be in the range of 3000-5000 MHz.Thus it is possible that the WLF and radio bursts are activated by the same accelerated electrons in the low corona and the electrons move both upward and downward.The different radiation phenomena may arise along various tracks of electron acceleration and injection.According to existing literature,as the hydrodynamic consequences of heating the solar chromosphere by the injection of an intense pulse of energetic electrons,two effects are dominant.One is the compression waves propagating towards the photosphere and the other is the ablation of material moving upwards.The momenta associated with them are equal and opposite,so a balance is kept.The radio data of complex type Ⅳ bursts in the late flare phase are accompaied by multi periodic dm continuum pulsations at two frequencies.These pulsations took place just before the formation of post flare loops,which correspond to the threadlike patterns in the middle of the active region as the initial sites of the flare.These phenomena manifest that after the WLF a configuration of denser plasma extended along magnetic field lines can be formed again in the corona.All the observational characteristics are probably the requirements of the occurrence of strong WLFs.