Why the temperature of the Sun’s atmosphere is it higher than at the surface of the star? Astrophysicists from around the world are pulling their hair before this observation since the 1940s Today, we finally know why. Astrophysicist Tahar Amari, CNRS researcher, and his team unearthed the heating mechanisms of the solar atmosphere. A discovery to be published on June 11th in Nature , the scientific journal.
A saucepan of boiling
On our Earth latitudes, the sun warms us . Up to thirty degrees on sunny days or forty if heatwave. Closer to the star, it’s a different story. At the heart of the Sun, the temperature reaches about 15 million degrees Celsius, down to 6,000 degrees at the “surface” of the star.
If the heat down to the surface, why increases-t it again as the distance from the Sun? Logic suggests that the further away, the more the temperature drops, in the manner of a chimney fire. If you put your hands close to the flames, it burns, but away, we feel less warmth. Here it’s the opposite. In the chromosphere, the lower atmosphere of the Sun, the thermometer climbs to 10,000 degrees in the solar corona, the upper part of the atmosphere, extending over several thousand kilometers, it exceeds one million degrees. As if it is burned away.
Thanks to their work simulation of the evolution of the sun, the three French researchers understand why. “At about 1,500 kilometers below the surface of the Sun, there is a thin layer that acts like a boiling pot,” says Tahar Amari, who made the discovery. “This plasma boiling soup creates and amplifies a magnetic field,” he continues. In rising to the surface of the Sun, this magnetic field is then a reserve of energy capable of heating the successive layers of the solar atmosphere.
A “vegetation” magnetic
be able to heat so far in the solar atmosphere, the energy reserve spreads via a “vegetation” magnetic unfolding like a mangrove. “The boiling pan is like a breeding ground for this magnetic mangrove”, decrypts the astrophysicist. Its roots collide and produce a multitude of micro-flares, and they tangle around trunks of trees magnetic, which form large vertical lines up the solar corona.
“When the roots knock these tree trunks, it then generates magnetic waves that make up the energy along the trunks, much like sound of a plucked string, “says the researcher. And it is the dissipation of the energy in the solar corona which increased the temperature at a million degrees or even two.
One of the sources of the solar wind
Tahar Amari welcomes this fundamental discovery. He and his team pulled the rug from under the feet of NASA who planchait also on the mystery of the temperature of the solar atmosphere. “It atmospheric heating mechanism actively participated in the creation of the solar wind, which move up to reach the Earth. But research must continue, he warned. The more we understand this, the better we can understand the consequences of solar winds on our planet. “
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