Solar Orbiter measurements connect one fold in the solar wind’s magnetic field with plasma from hot, closed loops in the Sun’s atmosphere. A newly published peer-reviewed study combines oxygen, carbon and helium signatures with solar images to investigate where the material came from. Its composition supports magnetic reconnection as a release mechanism; the result concerns one observed event and depends on modeling its source.
Solar Orbiter, a spacecraft studying the Sun, measured a magnetic fold containing material consistent with hot, closed loops in the solar atmosphere. The peer-reviewed observational study uses one event from 2 March 2022. Inside its largest fold, more highly charged oxygen and carbon ions appeared while helium became less abundant relative to protons. Those combined signatures linked the material to the hot loops.[1]
The Sun’s outer atmosphere, or corona, imprints its conditions on ions. Their charge states respond to its temperature and density near the Sun, then become largely preserved as the expanding plasma thins. Jesse T. Coburn and colleagues used solar images to estimate temperature and density and supplied them to a coronal model. Its predictions were compared with the spacecraft’s ion measurements.[1]
The candidate source was either the edge of a coronal hole or hot loops inside it. Reconnection between closed loops and open magnetic field offered a mechanism for releasing trapped plasma. Electron motion helped identify folds in the field rather than a complete change in its solar connection.[1]
Velocity and magnetic fluctuations matched an outward-propagating Alfvén wave, a disturbance travelling along a magnetic field. Locating the source depends on a model that assumes a static, current-free field; the chosen source-surface height also affects the connection. Larger samples of events are needed to assess how widely this relationship holds.[1]
