The “camp fires” at the Sun’s surface, shown here by arrows.
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July 17, 2020 13h29
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Zoom unheard of on the Sun and its “camp fires”
Juliette Collen
Agence France-Presse
PARIS — We had never seen the Sun so close: the first images delivered by the probe Solar Orbiter show “camp fires” bubbling near the solar surface, which may explain one of the mysteries of our star.
These phenomena so far unknown could in fact clarify the fact that it will be warmer in the solar corona, a million miles away, that on the very surface of our sun, a difference that defies the laws of nature. After 10 months of travel, the mission of euro-american has delivered the Thursday of the first images scientifically promising, thanks to its six telescopes observation giving the spacecraft a unique ability to take images of the surface of the star.
“The Sun never had been caught too near !”, welcomed to the AFP Anne Pacros, responsible for the payload of the mission Solar Orbiter, a collaboration between the european space Agency (ESA) and NASA, which took off from Earth on 10 February.
Taken to 77 million kilometres of the star (about half the Earth-Sun distance), these first close-up images have identified a new phenomenon of “campfires”, a mini-solar flares are ubiquitous near the surface, a detailed ESA during a press conference.
“The Sun may seem quiet at first, but when we look in detail we can see these eruptions thumbnails everywhere we look,” said David Berghmans of the royal Observatory of Belgium, principal investigator of the remote sensing instrument Extreme Ultraviolet Imager (EUI). These “campfires”, not visible in detail up here, “are small compared to the solar flares giant we can observe it from the Earth, millions or billions of times smaller”, says the physicist. They would do all the same approximately 400 kilometres — the size of a country. A more precise definition in the future will see smaller, hopefully.
“Holy grail” of solar physics
Scientists do not know yet if these “fires” are a simple miniature version of large flares or are the result of different mechanisms. But theories abound already that they could contribute to the heating of the solar corona, a phenomenon so far unexplained. The solar corona, the layer the more extreme of the Sun’s atmosphere which extends millions of kilometers into space, exceeds in fact the one million degrees while the surface of the Sun reaches “only” about 5500°C: this difference huge is contrary to the laws of physics, which mean that the farther from a heat source, the lower the temperature.
Understanding these mechanisms is considered to be the “holy Grail” of solar physics, emphasizes the ESA. Solar Orbiter has numerous other targets, including one to understand how the Sun controls the heliosphere, the middle magnetic ambient, which governs the interplanetary space, thanks to the four instruments, in-situ measuring the environment near the vehicle. It must also address the storms the charged energetic particles caused by solar flares, which can disrupt telecommunications networks and terrestrial networks of power – what is called space weather.
Unpublished pictures of the poles of the star, terra incognita, should also be disclosed by 2025, that may allow it to illuminate the workings of the solar magnetic field, detailed Sami Solanki, director of the Max Planck Institute for research on the solar system.
These first images are just the beginning, the mission Solar Orbiter is not yet in the phase of taken of scientific data. Intended to verify that all the instruments are working, “they exceed our expectations”, a delighted David Müller, scientific director of the project.
By march 2022, the probe will still return closer to the Sun, after a close-up of Venus and the Earth, the severity of which will repropulser to its orbit final, to 42 million kilometers from the Sun. Its mission for at least ten years must supplement that of the u.s. probe Parker Solar Probe, which approached more near to the Sun, but cannot take such instruments.
