A Quasi-Periodic Solar Radio Fluctuation at Microwave Band  

作　　者：许富英 黄光力 吴洪敖 

机构地区：[1]Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008 [2]National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012

出　　处：《Chinese Physics Letters》2005年第12期3229-3232,共4页中国物理快报（英文版）

基　　金：Supported by the National Natural Science Foundation of China under Grant Nos 10333030 and 10273025.

摘　　要：A rare but interesting solar radio fine structure, quasi-periodic fluctuations, on 25 August 1999 was observed at microwave band for the first time. They fluctuated initially at a nearly stable frequency level then at a reverse drift component up to 5.49 GHz, The individual fluctuation consists of a hi-directional drift component. The features are characterized by narrow bandwidth of △f/f≤3%, quasi-periodicity of ～ 100 ms as well as a slowly reverse and a rapidly normal drift rates on the hi-directional drift component. The associated data of the Yohkoh soft and hard x-ray telescope and Nobeyama radio heliograph at 17GHz showed that there are several bright spots （i.e. inhomogeneities） along the soft x-ray loop, and the locations of both radio and soft x-ray sources are closely consistent. Therefore, the fluctuations are most likely caused by the inhomogeneities within a flare loop. Based on the two-component atmospheric model, we suggest a three-component atmospheric model with large scale length λ and small scale lengths λ1 and λ2 to describe equilibrium atmosphere and inhomogeneity. With the beam model, the characters of fluctuations may be interpreted reasonably by the quasi-equidistant inhomogeneity along a flare loop.A rare but interesting solar radio fine structure, quasi-periodic fluctuations, on 25 August 1999 was observed at microwave band for the first time. They fluctuated initially at a nearly stable frequency level then at a reverse drift component up to 5.49 GHz, The individual fluctuation consists of a hi-directional drift component. The features are characterized by narrow bandwidth of △f/f≤3%, quasi-periodicity of ～ 100 ms as well as a slowly reverse and a rapidly normal drift rates on the hi-directional drift component. The associated data of the Yohkoh soft and hard x-ray telescope and Nobeyama radio heliograph at 17GHz showed that there are several bright spots （i.e. inhomogeneities） along the soft x-ray loop, and the locations of both radio and soft x-ray sources are closely consistent. Therefore, the fluctuations are most likely caused by the inhomogeneities within a flare loop. Based on the two-component atmospheric model, we suggest a three-component atmospheric model with large scale length λ and small scale lengths λ1 and λ2 to describe equilibrium atmosphere and inhomogeneity. With the beam model, the characters of fluctuations may be interpreted reasonably by the quasi-equidistant inhomogeneity along a flare loop.

关 键 词：LOW CORONA FLARE DRIFT 

分 类 号：P182[天文地球—天文学]