Searching for the Origins of the Fast Solar Wind

Abstract

Here we present the lowest-in-altitude observed signatures of the fast solar wind streams. They originate from coronal holes (CH) network boundaries, as seen in the low transition region (TR) line O iii 703.87 Å (T _e ≈ 8 × 10⁴ K). Higher in the solar corona, the plasma outflow is seen in the Mg ix 706.02 Å line (T _e ≈ 10⁶ K), as an increased blue-shift inside the CH region. An interesting change in behaviour is observed at the quiet Sun (QS)/CH boundaries, where plasma from the network changes its velocity sign, and, following the closed magnetic structures, falls back to the Sun. This is also the site where signature of magnetic reconnection between the open CH lines and the closed QS loops is seen, in the form of an increased number of bi-directional jets, which represent evidence for the slow solar wind origins.