Solar Orbiter, the observation satellite launched in February 2020, may have solved one of the mysteries of our star: the source of the solar winds. He would have achieved this feat thanks to images captured by the telescope on board: the Extreme Ultraviolet Image (EUI).
The Sun may rise and set every day before our eyes, but it remains very mysterious in many aspects. A tough enigma remains that of the solar winds, these enormous fluxes of particles charged with ions and electrons which are expelled at unimaginable speeds (between 300 and 800 km/s) from the atmosphere of the Sun. We have known about the phenomenon since 1859 thanks to the work of Richard Christopher Carrington, without really knowing its origin.
The European Solar Orbiter probe has highlighted minor jets on the surface of the star, which emit a billion times less energy than the largest solar flares. These emerge from dark regions of the Sun, which are called “coronal holes” and which are called “picoflare jets”. Although their size is rather small (a few hundred kilometers long) and their duration very short (a few tens of seconds at most), they could be at the heart of the phenomenon of solar flares. Moreover, one of these eruptions had struck Solar Orbiter before its flyby of Venus in 2022.
These small-scale jets could be charged enough with plasma (a state of matter of which the sun is made) heated to a very high temperature to be able to feed the solar winds. The researchers speculate these picoflare jets could play a significant role in this phenomenon, despite their relatively low energy.
Solar Orbiter: a valuable ally in understanding solar functioning
The Sun is slowly approaching its eleventh cycle of activity, and solar winds of colossal power have been observed during the months of July and August. The phenomena taking place on the surface of the star were difficult to understand before, but Solar Orbiter was entrusted with this great mission. Thanks to a close orbit around the Sun (45 solar radii, or 22 AU), the probe allows optimized observation of the various processes at the origin of the solar winds, but also of the magnetic field of our star.
The coronal holes had been suspected to be linked to solar winds for a while, but thanks to Solar Orbiter, the European Space Agency was able to obtain images of these picoflare jets in March this year. The only missing piece of the puzzle is observing these jets directly inside a coronal hole.
Sources: Engadget, Nature