NASA’s Parker Solar Probe has provided evidence for a “helicity barrier” in the atmosphere of our star, shedding light on a long-standing mystery in solar physics. The probe’s data suggests that the helicity barrier, which alters turbulent dissipation, can explain why the sun’s corona is much hotter than its surface.
The coronal heating problem has puzzled scientists for decades. Why is the outer atmosphere, or corona, so hot when it’s closer to the surface? Researchers have proposed two theories: turbulence and ion cyclotron waves. However, both ideas have their limitations. The new study, published in Physical Review X, suggests that a “helicity barrier” could be the key to resolving this issue.
According to the team’s analysis, the helicity barrier acts as a dam, stopping turbulent flows from heating up the plasma and instead diverting its energy into ion cyclotron waves. This mechanism links the two existing theories and resolves their individual problems.
The study’s findings provide clear evidence for the presence of the helicity barrier. By analyzing solar wind magnetic field measurements, researchers found that fluctuations in the magnetic field behave exactly as predicted when the barrier is active. The team identified specific conditions under which the barrier forms and discovered these values are common near the sun.
Further analysis is necessary to confirm the results, but the approach looks promising. The study has significant implications for understanding turbulent dissipation, the connection between small-scale physics and global properties of the heliosphere, and making predictions for space weather. The findings also have broader applications in astrophysics, particularly in other collisionless plasmas like those found in stars and other celestial bodies.
Source: https://www.iflscience.com/nasas-parker-solar-probe-finds-evidence-of-barrier-in-the-suns-2-million-kelvin-atmosphere-79933