行星际磁通量绳尺度及能量研究

Studies on the Sizes and Energies of Interplanetary Magnetic Flux Ropes

行星际磁通量绳是太阳风中一种重要的磁结构.从1995—2001年的Wind卫星的观测资料中认证了144个行星际磁通量绳.其时间尺度介于几十分钟到几十小时之间,其空间尺度呈现连续分布.通过估算磁通量绳单位长度的能量和总能量发现:磁通量绳的能量分布和耀斑的类似都呈现很好的幂率谱.通过讨论行星际磁通量绳和太阳活动爆发的关系,建议所有的小、中、大尺度通量绳都直接起源于太阳上的爆发,和磁云对应于通常的日冕物质抛射一样,中、小尺度的通量绳对应相对较小的日冕物质抛射.

Interplanetary magnetic flux ropes are a kind of important magnetic structure in solar wind. Previously, some scientists believed that there exists two kinds of interplanetary magnetic flux ropes. One is magnetic cloud, and the other is small magnetic flux rope identified by Moldwen et al（2000）. Both kinds of magnetic flux ropes approximately have the static, constant-alpha force-free, cylindrically symmetric configuration. But the small-scale magnetic flux ropes have no famous expansion and lower proton temperature behaviors. Moldwen et al（2000） suggested that the two samples are from two different source regions： magnetic clouds from reconnection in the solar corona, and these small-scale flux ropes from reconnection across the heliospheric current sheet （HCS）. In observations from 1995 to 2001 from the Wind space- craft, 144 interplanetary magnetic flux ropes were identified in the solar wind around 1 AU. Their durations vary from tens of minutes to tens of hours. These magnetic flux ropes include many small- and intermediate-sized structures and display a continuous distribution in size. Energies of these flux ropes are estimated and it is found that the distribution of their energies is a good power law spectrum. The possible relationship between them and solar eruptions is discussed. It is suggested that like interplanetary magnetic clouds are interplanetary coronal mass ejections, the small- and intermediate-sized interplanetary magnetic flux ropes are the interplanetary man- ifestations of small coronal mass ejections produced in small solar eruptions. However, these small coronal mass ejections are too weak to appear clearly in the coronagraph observations as an ordinary coronal mass ejection.