September 30, 2024 | 15.07
READING: 4 minutes
The European Solar Orbiter mission made a big step forward in understanding the Sun, especially through the use of the Metis coronagraph, which allowed scientists to observe in detail the propagation of turbulent motions of the solar wind. Developed by an international research team coordinated by INAF and with the participation of other Italian institutions such as CNR and several universities, the Metis coronagraph was fundamental for observing turbulent phenomena directly from the solar corona. This advanced tool, capable of blocking direct sunlight, it captures visible and ultraviolet light from the corona, revealing the turbulent movements of the solar wind from its origins.
It must be dated back to October 12, 2022, when thanks to Metis observations, scientists collected crucial data on the dynamics of the solar wind, confirming that turbulence begins in the innermost areas of the solar corona and expands towards space. This data is considered essential to improve understanding of the processes that govern space weather and to predict potential impacts on our planet. 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.
“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 Manager of the Italian contribution to the mission.
Below is the link to the video where 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. Credits: ESA & NASA/Solar Orbiter/Metis & EUI Teams and D. Telloni/INAF
By blocking direct light from the Sun, the Metis coronagraph is capable of capturing the weakest 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. 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 Stangalini, researcher and ASI Program Manager of the Solar Orbiter mission. “This significant achievement is just the latest in a long series of successes and offers great hope for the future. In the coming years, in fact, 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.
The article “Metis observation of the onset of fully developed turbulence in the solar corona“
was published in The Astrophysical Journal Letters.
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