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Magnetic Tornadoes May Heat Solar Corona

The sun's outer atmosphere, or corona, is much hotter than the surface. Giant magnetic tornadoes may be behind the heat transfer. John Matson reports

The sun is hot. That’s obvious. But it’s where it’s hot that has physicists puzzled.

The sun’s outer atmosphere, or corona, is much hotter than the surface, even though the surface is closer to the nuclear fusion reactor of the solar interior. Why that should be is one of the big questions in solar physics. There have been several hypotheses for how all that heat arrives in the corona, from oscillating magnetic waves to jets of hot plasma.

Now a team of European researchers has discovered a new possibility: giant magnetic tornadoes. These supersize swirls can be some 1,500 kilometers across. And they’ve been seen on the sun’s surface and in its lower atmosphere. With the help of NASA’s Solar Dynamics Observatory the researchers spotted the tornadoes reaching up into the corona as well. They reported their finding in the journal Nature. [Sven Wedemeyer-Böhm et al., "Magnetic tornadoes as energy channels into the solar corona"]

The solar swirls are plentiful—more than 10,000 of them dot the sun at any given time. And they could funnel quite a bit of energy up into the solar atmosphere. It’s too early to say how big a role the tornadoes play in heating the corona. But their discovery is sure to make a hot topic even hotter.

—John Matson

[The above text is a transcript of this podcast.]

[Scientific American is part of Nature Publishing Group.]

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