It is one of the oldest mysteries in the sun: why the overheated surface of this luminescent plasma sphere is actually cooler than its outer atmosphere, the latter also known as the corona.
Scientists now have new insights into this problem. The answer lies in a strange phenomenon of the sun. It has never been observed before: in the newly discovered topological magnetic structure called Raining Null Point, there are a lot of The plasma raindrops are lowered.
On Earth, water evaporates into steam, rises into the atmosphere, and then cools into rainwater, an effective water cycle.
On the hot surface of the sun, a similar cyclic process controls the so-called sundial: in the solar flare, the superheated plasma transpires from the surface and rises into the solar atmosphere along the invisible magnetic ring.
When the plasma is cooled away from the sun, it forms a fiery rain arc that condenses and descends along the invisible magnetic path to the photosphere.
Basically, both the Earth and the Sun have rainfall, just following different cooling processes.
Emily Mason, a solar physicist at the Catholic University of the United States, introduced her preliminary research in an interview with Science News last year: “The physics is basically the same as the rain process on the Earth and the Sun.”
Nowadays, Mason’s paper has just been published, and it has discovered an unprecedented sundial: it mainly occurs in an unexpected place and is related to new phenomena in solar physics.
As part of her work at NASA’s Goddard Space Flight Center, Mason is studying the sundial rain in a giant magnetic structure known as a helmet-like belt that can extend a million miles from the surface of the sun. local.
After several months of searching, Mason found nothing, but with the help of NASA’s Sun Dynamics Observatory (SDO) data, she did find a tiny magnetic ring closer to the sun’s surface, where there seems to be plasma rain.
But only when Mason shared these data with NASA researchers, realized that the smaller-scale magnetic structures—the team called Raining Null Point Topologies (RNPTs)—are a new phenomenon.
“I said, ‘Wait… Where did you see it?’,” NASA solar scientist Nicholeen Viall explained. “I don’t think anyone has seen this before!”
According to the researchers, RNPT occurs about 50,000 kilometers above the surface of the sun. It sounds grand, but it’s much smaller than Mason’s original helmet-like flow—only 2% of the height of the magnetic strip.
Smaller scales can also explain some things about the sundial.
“These loops are much smaller than we want,” said NASA solar physicist Spiro Antiochos. “So this is telling you that the heating effect of the sundial is more localized than we think.”
The new findings do not tell us how RNPT makes the sun’s temperature higher than the surface – which is still a hypothesis – but the plasma phenomenon and its duration suggest that it may form the main part of the answer.
Their paper explains: “In all observations, the appearance rate and rainfall frequency of this structure provide convincing support for the universality of this phenomenon. In all cases, the seemingly identical magnetic ring exists. It lasts for several days, so it is obviously not an accidental phenomenon.”
However, the strange thing is that not all plasmas involved in the rain cycle will return to the sun.
In the data, the researchers also saw a phenomenon called magnetic interchange reconnection, that is, the plasma on the closed magnetic ring may leave the loop and even become the driving force of the solar wind.
More observations and research are needed in the future, but RNPT may be an important factor in helping scientists understand the solar heat distribution and plasma flow differences.