Quasi-periodic outflows observed by the X-ray telescope onboard Hinode in the boundary of an active region

Abstract

Persistent outflows have recently been detected at the boundaries of some active regions. Although these outflows are suggested to be possible sources of the slow solar wind, the nature of these outflows is poorly understood. Through an analysis of an image sequence obtained by the X-Ray Telescope onboard the Hinode spacecraft, we found that quasi-periodic outflows are present in the boundary of an active region. The flows are observed to occur intermittently, often with a period of 5-10 min. The projected flow speed can reach more than 200 km s-1, while its distribution peaks around 50km s-1. This sporadic high-speed outflow may play an important role in the mass loading process of the slow solar wind. Our results may imply that the outflow of the slow solar wind in the boundary of the active region is intermittent and quasiperiodic in nature.