Ⅲ型太阳射电爆发精细结构的观测研究

Observational study on the fine structures of solar type Ⅲ radio bursts

Ⅲ型太阳射电爆发是一种瞬时的太阳射电辐射增强现象,在动态频谱上常常表现为由高频向低频快速漂移的宽带射电信号;为能量电子沿磁力线从日冕向外传播过程中激发的等离子体辐射,辐射的基频频率接近当地等离子体频率.某些Ⅲ型暴具有特殊的形态或精细结构,包括J, U和N型暴,反向Ⅲ型暴和Ⅲ型暴对, Ⅲb型暴,以及Ⅲ-L型暴.这些精细结构可用于诊断电子密度、能量电子速度和日冕大气湍流等日冕参数以及预报空间天气,被视为太阳爆发过程和太阳射电研究的一个关键点;而且有些精细结构的形成原因仍不明确,需要进一步研究.本文将介绍Ⅲ型暴精细结构的观测研究进展以及将来研究中需要关注的问题.

Solar type Ⅲ radio bursts are transient radio radiation enhancement phenomena, which appear in the solar radio dynamic spectrum as signals that rapidly drift from high to low frequencies. The bursts are believed to be the plasma emissions excited by energetic electrons that propagate outward from the corona along the magnetic field lines, and the emission frequency is close to the local plasma frequency. Certain type Ⅲ radio bursts have special morphologies or fine structures, such as the types J, U, and N and the inverted/bi-directional drift types Ⅲ, Ⅲb, and Ⅲ-L radio bursts. These fine structures can be used to diagnose the coronal parameters,such as the electron densities, atmospheric turbulences, and energetic electron velocities. In addition, these structures can forecast the space weather. The burst was regarded as the key point in the study of solar eruptions and solar radio bursts. The reasons for the appearance of fine structures are still unclear, and further studies are needed. This article investigates the progress made by the observational studies of the fine structures of the solar type Ⅲ radio burst.