日冕物质抛射基本物理参数的统计特征

Statistical Properties of Coronal Mass Ejections

日冕物质抛射(CME),是太阳大气中尺度最大,最为壮观的太阳活动现象.自1971年12月14日,人类第一次观测到CME以来,CME受到了越来越多的关注,许多空基日冕仪和地面设备对其观测得到了丰富的观测资料.但是,直到现在,CME的基本物理参数研究中还是存在一些不确定性,当然其中也受观测设备局限性的制约.该文综述了近年来CME基本物理参数的统计特征——速度、加速度、角宽度及纬度等——研究的新进展,指出了这些基本物理参数中存在的一些问题,并提出了今后日冕物质抛射研究中要加强的一些重大问题.

Coronal Mass Ejections（CMEs）, known as the most energetic form of solar magnetic activity, are now believed to be the main sources of the strong interplanetary disturbances that cause moderate to intense geomagnetic storms. Since CMEs were first discovered on Dec 14 1971 using the seventh Orbiting Solar Observatory （OSO-7） coronagraph, they have drawn more and more attentions. Several spaceborne coronagraphs and ground-based instruments have found a number of CMEs, which give a good chance to study them in details. Although CMEs are analysed for decades, there are still some uncertainties for a accurate measure of physical parameters of CMEs, for example, the CME latitude is still obtained just from the central position angle （CPA） of the CME, assuming that CMEs propagate radially away from the solar source region. In this paper, we show the recent main progress on the statistical properties of fundamental physical parameters of CMEs, such as their speed, acceleration, width, latitude distribution and so on, in section 2. And some uncertainties in the determination of these fundamental physical parameters are presented in section 3. These uncertainties due to that （1） these parameters are not observed from a start phase of CMEs; （2） we measure these parameters with them projected just in the sky plane. Finally, we propose some important problems, which should be paid much more attentions for understanding CMEs well.