An observation of solar active region expansion into the heliosphere

According to current models, solar closed-field active regions are isolated from contributing directly to the solar wind except through small- or large-scale magnetic reconnection, including coronal mass ejections. Here we show the first direct evidence of active regions contributing directly to the solar wind by a steady-state, quiescent expansion. Advanced image processing of coronagraph data reveals a large system of nested closed-field magnetic structures expanding and accelerating to heights of at least 14 R⊙ within a helmet streamer above a large active region. The system persists for several days, and must therefore be an important contribution to the slow solar wind.