日球边界射电辐射的研究进展

日球边界射电辐射是太阳系最强的射电辐射现象,辐射功率至少达1013 W,能够提供日球边界附近高能电子束和背景磁等离子体结构的重要物理信息.自1983年旅行者号卫星首次探测到日球边界射电辐射后,其便受到研究者们的广泛持续关注.日球边界射电辐射大致有两类:辐射频率相对较高的瞬时辐射或称漂移辐射以及辐射频率相对较低的持续辐射或称非漂移辐射.通常两类辐射都从大约2 kHz开始,漂移辐射具有向高频率漂移的特征,频漂率约为1–3 kHz/yr,频率范围1.8–3.6 kHz,持续时间较短大致100–300 d;非漂移辐射没有明显的频率漂移,频率范围1.8–2.6 kHz,持续时间较长大致3 yr.目前普遍认为日球边界射电辐射与激波有关.介绍了该射电辐射可能的辐射产生源区、辐射物理机制以及与辐射相关的激波来源,并且讨论了尚存在的科学问题以及展望了未来可以进一步开展的研究.

Research Progress of the Heliospheric Radio Emissions

The heliospheric radio emissions are the strongest radio emissions phenomenon in the solar system, with a radiation power of at least 10¹³W, which can provide important physical information of high energy electron beam and magnetic plasma structure near the heliospheric boundary. Since the first detection by the Voyager spacecraft in 1983, those radio emissions have widely and continuously attracted much attention from researchers. There are generally two types of the heliospheric radio emissions: instantaneous or drifting emission with relatively high frequency, and continuous emission or non-drifting emission with relatively low frequency. Usually, both types of emissions start from about 2kHz. For the drifting emission, it has the characteristic of drifting to high frequency, the drifting rate is about 1--3kHz/yr, the frequency range is 1.8--3.6kHz, and the duration is about 100--300days. For the non-drifting emission, it has no obvious frequency drift, the frequency range is 1.8--2.6kHz, and the duration is about 3yr. It is generally believed that the heliospheric radio emissions are related to shock. In this paper, the possible source region of the radio emissions, the emission mechanisms, and the source of shock related to the emissions are introduced. Furthermore, the existing scientific problems and the future perspectives on the research of heliospheric radio emissions are discussed.