Science

The biggest mystery behind the Sun: why its corona is hundreds of times hotter than its surface

Astrophysicists who study the Sun have faced a mystery that contradicts logic for decades.

They wonder how it is possible that the solar corona, the outermost layer of our star, is hotter than the surface itself.

While the crust has a temperature of about 5,500 degrees Celsius, the corona can reach millions of degrees.

“Imagine that you are sitting next to a campfire. Close to it, it is nice and warm and when you move away from the fire, it is colder. This is the opposite of what seems to happen on the Sun,” explains NASA.

Now a new find gives new clues to solve the enigma .

Unraveling this mystery is important because the influence of the corona is not limited to the space around the Sun.

The particles of that layer move so fast that they escape the gravity of the star and its influence extends throughout our solar system.

” The Earth is like a kite suspended in space at the mercy of the winds. The sphere of influence of the Sun is very large and we are inside it. We are at the mercy of that solar wind,” he explains to the BBC. Franco-Colombian astrophysicist Patrick Antolin Tobos, from the University of Northumbria in Newcastle, UK.

This mass that is transported by solar winds can affect communications, satellites, aircraft navigation systems and even electrical systems.

And if we talk about space conquest , understanding how these currents work is essential.

Hence, there is a field of science dedicated to studying solar storms and that in many countries the activity of the star is considered a national security issue.

The great difficulty is knowing how this solar wind is created and why its particles seem to be released as explosive jets.

The answer is that there is something that heats the crown , but what is it?

2,000 nuclear bombs

One of the explanations, which has now become more plausible, is that the corona’s magnetic field twists and reconfigures itself.

This event releases an energy equivalent to that of 2,000 nuclear bombs like those in Hiroshima.

It is a phenomenon that lasts less than 10 seconds and that occurs at a speed of 500,000 kilometers per hour.

This phenomenon is called magnetic reconnection.

It was theoretically described by the astrophysicist Eugene Parker , who gives its name to the NASA probe that is currently orbiting the sun.

Parker never had in his hands the scientific evidence that the Sun’s magnetic energy is converted into thermal energy and heats the solar corona.

However, the team led by Antolin Tobos published this week in the scientific journal Nature Astronomy the first detection of a phenomenon that confirms Parker’s theory: nanojets.

“The molded magnetic field the solar corona and heated. There are magnetic field lines everywhere and are anchored in the sun. That means they are constantly being moved from one side to the other. They are like threads tied to the ol ” says Antolin Tobos.

What Parker was saying is that these magnetic field lines have to break because they hold so much energy that it has to come out somehow.

” The magnetic lines are broken to reconnect at another site. They are reconfigured in other ways and at the same time that this happens they emit energy”, explains the Colombian scientist.

This is one of the theories that explain the reason for the temperature of the corona, but until Antolin Tobos’ team made its discovery, there was no evidence of the mechanism responsible for it.

500 kilometers wide

The sparkles or nanojets a series of small, but numerous, explosions in the atmosphere of the star, could be observed thanks to the advancement of technology.

It’s something Parker didn’t count on.

Using observations from NASA’s IRIS and SDO satellite telescopes and another called Hinode that orbits the Sun, the team learned that nanojets can be up to 500 kilometers wide and 1,500 kilometers long.

And they verified how the temperature of one of the solar sections increased while the phenomenon took place.

“That was the first time that they were detected and we saw an avalanche effect. At first there are a few and then they reproduce throughout the structure. In a range of about 10 minutes, that structure heated up millions of degrees “, Antolin recalls.

NASA itself recognized the contribution of this research in which its IRIS solar observation satellite has been key .

“In a paper published today in Nature Astronomy, the researchers report the first sharp images of nanojets , thin, bright lights that travel perpendicular to the magnetic structures of the solar corona.”

More exploration

But this explanation, Antolin says, might not be the only one that answers the scientific enigma.

“The solar corona is so rich in physical processes that these nanojets are likely to be seen in certain parts, but not elsewhere. This Parker theory has never been directly observed. This is a big step towards solving the The problem is not the definitive one. There is still a little left, “says the astrophysicist.

In scientific terms, he believes that for the mystery to be completely solved, science has to photograph nanojets everywhere and for that a technology that allows to cover wider areas is necessary.

“These nanojets are so small and so fast that in one photo they are and in the next they are no longer. But my intuition tells me that we just have more resolution, we are going to see them in the central part of the distribution”, believes this frank astrophysicist. Colombian.

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