Flying through “Magnetic Construction Site” in the Sun's Corona
During a solar eruption, the Parker Solar Probe experienced magnetic reconnection in the corona up close for the first time. Solar Orbiter also tracked the event.
NASA’s Parker Solar Probe was in the right place at the right time on September 5 and 6, 2022, during its flight through the corona, the Sun’s outer atmosphere. Current analyses show that the probe passed through a particularly exciting region: In connection with a violent burst of radiation, the structure of the Sun's magnetic field underwent a fundamental reorganization. This process, which researchers refer to as magnetic reconnection, releases large amounts of energy. At the same time, ESA's spacecraft Solar Orbiter observed the event from a greater distance. Data from both probes suggest that the reconnection process lasted more than 24 hours. Researchers led by the Southwest Research Institute (USA) report their findings in the journal Nature Astronomy. The Max Planck Institute for Solar System Research (MPS) is involved in the study.
The Sun is shrouded in an atmosphere of plasma heated to temperatures of up to one million degrees. Strong, changing magnetic fields determine the happening there and direct the plasma flows. Researchers refer to reconnection when the magnetic field lines locally rearrange themselves, releasing energy stored in the magnetic field. This often triggers eruptions in which the Sun ejects particles and radiation into space. Particularly violent eruptions can be dangerous: If the solar bombardment spreads toward Earth, communication systems, power grids, and satellites can be damaged. Models that describe magnetic reconnection as accurately as possible help to predict such events at an early stage.
The solar flare on September 5 and 6, 2022, offered a unique opportunity to take a closer look than ever before. At that time, Parker Solar Probe had reached the point in its orbit closest to the Sun and was passing through the Sun's corona. Less than ten million kilometers separated the probe from the star. At the same time, Solar Orbiter observed the magnetic fields at the visible surface of the Sun from a distance of just over 100 million kilometers. This is where the coronal magnetic fields originate.
The latest analysis of the observational data from both probes now suggests that the Parker Solar Probe did indeed pass through a reconnection zone in the solar outer atmosphere on that day. The reconnection lasted about 24 hours. Such lengthy magnetic restructuring had never been measured directly before. The data will help to understand how energy is transferred and particles are accelerated into space during magnetic reconnection. The measurements confirm existing models describing this process and may help refine the current understanding of reconnection. For example, it is still unclear why some reconnection events are short-lived, while others last for many hours.
NASA's Parker Solar Probe was launched into space in August 2018 with the goal of “touching the Sun.” Its orbits are highly elliptical and, since 2021, have repeatedly taken the probe through the Sun’s outer atmosphere. There, the probe studies the electromagnetic fields, waves, and particles surrounding it. However, due to its extraordinary proximity to the Sun, Parker Solar Probe is unable to look directly at our star. The instruments and probe would overheat. Since 2020, ESA’s space probe Solar Orbiter has been providing a solution. Although the probe keeps a greater distance from the solar fireworks, it collects data from all layers of the Sun. Some of the scientific instruments are pointed directly at our star. The Polarimetric and Helioseismic Imager (PHI), which was developed and built under the direction of MPS, maps the processes on the solar surface and measures, among other things, the direction and strength of the magnetic field there.
