The solar wind is an incessant flow of charged particles coming from the Sun, whose trend is far from constant. In their motion in space, solar wind particles interact with the Sun’s variable magnetic field, following chaotic and fluctuating trajectories, a phenomenon called turbulence.
The footage obtained from the European Space Agency’s Solar Orbiter mission thanks to the coronagraph Metis designed by the National Institute of Astrophysics (INAF), University of Florence, University of Padua, CNR-Ifn, and created by the Italian Space Agency with the collaboration of the Italian industry, confirm something that has long been suspected: the turbulent motion of the wind solar begins very close to the Sun, within the portion of the solar atmosphere known as the corona. Small disturbances that affect the solar wind in the corona are carried outward and expand, generating turbulent flow farther into space.
“This result has opened a new window on the physics of the solar wind thanks to Metis, the newly developed coronagraph – entirely Italian – on board the Solar Orbiter, which allowed high-rate acquisitions of coronal images with an unprecedented contrast between the coronal signal and background” he comments Silvano Fineschi of INAF and Scientific Responsible of the Italian contribution to the mission. By blocking direct light from the Sun, the Metis coronagraph is able to capture the weaker visible and ultraviolet light coming from the solar corona. Its high-resolution, high-cadence images show detailed structure and movement within the corona, revealing how the movement of the solar wind already becomes turbulent at its roots. The footage used by the research team to observe the propagation of turbulence in detail was obtained on October 12, 2022 and sequenced to create a video animation. In particular, the red ring in the video shows Metis’ observations. On that date, the probe was only 43.4 million km from the Sun, less than a third of the Sun-Earth distance. The image of the Sun in the center of the video was taken by Solar Orbiter’s Extreme Ultraviolet Imager (EUI) on the same day as the Metis observations.
“The high spatial and temporal resolution of Metis is shedding new light on the physical mechanisms that regulate the solar wind and its propagation, allowing a better understanding of the processes through which the Sun determines the physical conditions of interplanetary space with effects also on Earth ” he says Marco Stangaliniresearcher and ASI Program Manager of the Solar Orbiter mission. “This significant achievement is just the latest in a long line of successes and offers great hope for the future. In fact, in the coming years, Solar Orbiter will tilt its orbit, allowing us to observe the Sun from a completely new perspective for the first time.”
Turbulence affects how the solar wind is heated, how it moves through the Solar System, and how it interacts with the magnetic fields of the planets and moons it passes through. Understanding solar wind turbulence is critical to predicting space weather and its effects on Earth.
Video description: The Sun is shown in the center, surrounded by a ring that displays part of the solar corona imaged by Solar Orbiter’s Metis coronagraph. The data shows changes in the brightness of the solar corona, which is directly related to the density of charged particles present within it. These changes are made visible by subtracting consecutive coronal brightness images taken two minutes apart. The red regions show no change, while the black and white regions show positive and negative changes in brightness. This reveals how charged solar wind particles within the corona move in a chaotic and turbulent manner. Video credits: ESA & NASA/Solar Orbiter/Metis & EUI Teams and D. Telloni/INAF
