How Crazy Magnetic Fields Drive the Sun Mad
By Paul M. Sutter
Solar coronal jets are fast moving plumes of plasma that erupt suddenly from the polar regions of the Sun. Astronomers believe that these help heat up the solar corona, but the physics behind the formation of these jets is poorly understood. Recently a team of astronomers have used observations with the Solar Dynamic Observatory and the Solar Orbiter to discover that multiple intertwining magnetic fields that connect and reconnect can power these fast moving jets.
Normally in everyday situations we don’t care about magnetic fields all that much. Sure, they may wiggle our compasses around ,but they aren’t nearly powerful enough to influence us. The same is not true with the Sun. Usually the Sun has a powerful but relatively sedate magnetic field. But as the Sun rotates it can tangle up that magnetic field, forcing the field lines to twist up on themselves into thick ropes.
We can see when the magnetic fields get extremely tangled, because when bundles of magnetic field lines puncture the surface we see it as a sunspot. Eventually these tangled magnetic field lines get so caught up in themselves that they snap, releasing an enormous amount of energy. This is the mechanism behind the release of solar flares and coronal mass ejections.
And similar processes are probably behind coronal jets, at least according to new observations. A team of astronomers recently used multiple wavelengths of radiation to study jets at different times with both the Solar Orbiter spacecraft and the Solar Dynamics Observatory. They found that the bulk of the material in the jet was moving between 100 and 200 km/s, but with some of the features within the jet reaching speeds of over 700 km/s .
They also observed kinks, bends, and pinches in the jet. The team interpreted these features as places where the magnetic field is pinching strongly on the jet or in the process of breaking, where it can release its energy to continue powering the plasma.
This research helps potentially understand the nature of the solar corona. The corona is the thin, tenuous atmosphere that extends beyond the surface of the Sun. Despite its great distances from the solar surface, it has a temperature of over a million Kelvin. That’s much hotter than the surface of the Sun itself. Astronomers do not yet fully understand how the corona gets so hot. But observations like these suggest that coronal jets may play a role, because they release an enormous amount of energy directly into that region.
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January 16, 2023 at 12:32AM
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