Many small-scale “picoflare jets” within a coronal hole power Sun’s solar wind

Extreme ultraviolet images of the Sun obtained by the Solar Orbiter spacecraft have revealed numerous small-scale jets within a coronal hole. These so-called “picoflare” jets, the study’s authors say, could supply energy and plasma to the solar wind – a continuous stream of charged particles flowing outwards from the Sun’s corona, and an important component of space weather within the heliosphere. Solar wind streams have been traced to coronal holes, areas on the Sun’s outer atmosphere. While it’s thought that coronal holes could be the source region of solar wind, how wind emerges from them remains unknown. Here, Lakshmi Chitta and colleagues report observations of a coronal hole using the Extreme Ultraviolet Imager (EUI) instrument on board the Solar Orbiter spacecraft. Chitta et al. identified a variety of small-scale plasma jets within the coronal hole. These widespread yet faint jets, only a few hundred kilometers across, were observed to last only 20 to 100 seconds and reach speeds of ~100 kilometers per second. They appear to be powered by magnetic reconnection. Given their relatively low kinetic energies, Chitta et al. refer to these features as picoflare jets. According to the authors' calculations, plasma outflows from numerous and frequent picoflare jets, channeled along the open magnetic field lines of coronal holes, could provide substantial mass and energy flux to the solar wind throughout the solar cycle. In a related Perspective, Ignacio Ugarte-Urra and Yi-Ming Wang discuss the study and its findings in greater detail.