日冕微波辐射甚长周期脉动的观测证据  

The Observational Evidence of Microwave Pulsations with Very Long Periods in the Corona

作　　者：谢瑞祥[1] 汪敏[1] 施硕彪[1] 许春[1] 李维华[1] 颜毅华[2] R.A.Sych A.T.Altyntsev 

机构地区：[1]中国科学院国家天文台云南天文台,昆明650011 [2]中国科学院国家天文台,北京100012 [3]Institute of Solar-Terrestrial Physics,126 [4]Institute of Solar-Terrestrial Physics

出　　处：《天文学报》2003年第1期8-15,共8页Acta Astronomica Sinica

基　　金：国家自然科学基金(19833050;19973016);"973"项目(G2000078403)资助

摘　　要：利用国家天文台微波(1.0-2.0 GHz和2.6-3.8GHz)射电频谱仪于1998年9月23日观测到了一个稀少事件,它是一个伴生多重周期脉动、Ⅲ型爆发和类I型噪暴的复杂射电Ⅳ型爆发,着重介绍该爆发所具有的多重长周期(约7.3、4.9、3.7、1.2和0.4分钟)脉动成分。这个长周期脉动可能是归因于在封闭环中的驻波模式,由于光球层速度场驱动的MHD的Alfven驻波横穿磁场,导致了对射电辐射的调制。此外,由于这些脉动存在向下的运动,也不排除在一个封闭环或开放场结构中传播的扰动引起振荡的可能性。因为Alfven波的共振与光球层5分钟振荡模式相联系,所以甚长周期的脉动可能来自光球层驱动源的假设,可以说明日冕磁环和光球层之间存在一个互相耦合的可能性。A rare event was observed with the microwave(l.0-2.0 and 2.6-3.8 GHz) radio spectrometer (in Beijing) at National Astronomical Observatory of China on September 23, 1998. This event is a complex radio type IV burst associated with multi-periodic pulsations, type Ⅲ bursts, and type I-like noise storm. The pulsative components containing multiple long periods (about 7.3, 4.9, 3.7,1.2 and 0.4 minutes) are focused in the paper. This pulsations may be attributed to the standing Alfven waves mode in the close coronal loop. Because the standing Alfven MHD wave driven by the photospheric velocity field passing the magnetic field transversely, the modulation of radio emission is caused. Moreover, because there is a frequency drift downwards ( towards photosphere ) of the pulsations, it is not excluded the possibility that the oscillation is caused by the propagating disturbance in a close loop or open field structure. With the resonance of the Alfven waves is associated with the mode of potospheric 5 minute oscillations, the propose that very long periodic pulsations are come from the driving origin of the photosphere explains the existing possibility of couple existed between the coronal loop and the photosphere.

关 键 词：日冕 微波辐射 甚长周期脉动 射电频谱仪 驻波模式 光球层 磁环 

分 类 号：P182.6[天文地球—天文学]