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Scientists have long wondered why the hot soup of charged particles in the Sun’s atmosphere gets hotter as it moves away from the Sun’s surface.
New research may provide the answer, finding that the extremely hot nature of the Sun’s outer atmosphere, or “corona,” may be due to the intriguing behavior of small-scale waves in this nebular plasma. Known to scientists as “kinetic Alfvén waves,” or “KAWs,” these waves are wave-like vibrations of magnetic fields generated by movements in the Sun’s photosphere.
The findings could provide a key clue to solving the seemingly physics-defying “coronal heating mystery” that explains why the corona is hundreds of times hotter than the visible solar “surface,” or photosphere, which emits all the light we see from the sun.
The team behind this research, led by Syed Ayaz, a researcher at the University of Alabama in Huntsville, theorizes that as KAWs spread out, they disperse and heat the sun’s corona, serving as an important, but small-scale mechanism by which energy is transferred within the sun’s plasma.
Relating to: Massive X-class solar flare erupts from Earth-facing sunspot (video)
Ayaz said this phenomenon could explain why the temperature of the Sun’s visible surface is about 10,000 degrees Fahrenheit (5,500 degrees Celsius), while the temperature of the corona, which makes up the uppermost part of the Sun’s atmosphere, is over 2 million degrees Fahrenheit (1.1 million degrees Celsius).
“For decades, Alfvén waves have proven to be the best candidate for transporting energy from one place to another,” Ayaz said in a recent statement. expression“No solar spacecraft mission has yet made predictions about these near-sun phenomena.”
How the corona warming mystery defies physics
Most of the sun’s energy comes from its core, where nuclear fusion takes place. This is should It gets hotter as you go deeper. Most of our star’s layers follow this principle. However, the corona, even though it is millions of miles farther from the solar core than from the sun’s surface, is still much hotter than the photosphere.
Ayaz and his colleagues studied the effect of KAWs in plasma floating up to a height equal to 10 times the radius of the sun. At these distances, when the waves interact with the sun’s charged plasma, which is full of “ions” — atoms stripped of their electrons — “they quickly scatter and transfer their energy entirely to the plasma particles in the form of heating,” Ayaz said.
The team’s findings suggest that energy from the waves could reach the corona and heat it, but it is not yet known how much they contribute to its temperature.
“This new research provides important insights into the critical problem of how the energy in a magnetic field is converted to heat a plasma composed of charged particles such as protons and electrons,” said Gary Zank, director of the Center for Space Plasma and Aeronautics Research at the University of Alabama, who was not involved in the study.
The findings of the latest study were reinforced by data from the European Space Agency Sun orbit and NASA’s Solar Dynamics Observatory (SDO). SDO found before It is thought that another type of high-frequency, arc-like magnetic wave emitted from the corona could also transfer large amounts of energy to the sun’s outer atmosphere over time, contributing to the heating of the millions of degrees of heat in the layer.
Similar processes that provide heat to the sun’s corona were the focus of a recent NASA sounding rocket mission. MaGIXS-2—Short for the second flight of the Marshall Grazing Event X-ray Spectrometer, this instrument was launched into space for a few minutes in mid-July to collect X-rays from the sun.
These beams, in particular, show how frequently bursts of energy are released from within our star and could help scientists learn more about how the corona heats up.
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As scientists continue to piece together the puzzle of how the sun’s corona gets so hot, other heating mechanisms related to the sun’s magnetic field are being ruled out. For example, scientists suspected that certain S-shaped bends in the sun’s magnetic field contained a lot of magnetic energy, which was released into the surrounding plasma, heating it up and accelerating storm-sparking solar winds.
But as reported in a separate paper published Monday in The Astrophysical Journal Letters, an analysis of Parker Solar Probe’s first 14 orbits around the Sun found no evidence of the sought-after feature inside the corona.
Mojtaba Akhavan-Tafti, a research scientist at the University of Michigan who led the study, wrote in a paper: expression It is stated that the Parker Solar Probe’s journeys to the sun in December of this year could provide more information about the decades-old mystery.
The team’s work was published last week in The Astrophysical Journal.