Kinetic Alfvén waves may be the key to the mystery of solar coronal heating

Saeed Ayaz, a researcher at the University of Alabama in Huntsville (UAH), published a paper in Scientific Reports based on a first-of-its-kind study examining kinetic Alfvén waves (KAWs) as a possible explanation for why this is the case. did. The solar corona, the outermost layer of the Sun’s atmosphere, is about 200 times hotter than the surface of the Sun itself.

This new study, also the first of its kind, provides further evidence that these electromagnetic phenomena, which are abundant throughout the plasma universe, may be essential to solving solar physics’ greatest mysteries. Ta.

“Our previous research investigated wave-particle interactions, focusing on the dynamics of kinetic Alfvén waves in plasma,” said UAH’s Graduate Research Center for Space Plasma and Aeronautics Research (CSPAR). said Ayaz, his assistant. University of Alabama System. “However, certain important aspects remained unexplored, such as the energy distribution of the KAW, the net resonance velocity of the particles, and the characteristic decay length of the KAW.”

Kinetic Alfvén waves are oscillations in the magnetic field as charged particles move through the solar plasma. Waves are formed by the movement of the photosphere, the sun’s outer shell that emits visible light. “Attenuation” is a physical phenomenon that occurs in a plasma when a charged particle interacts with a wave electric field, where the KAW transfers energy to the particle, leading to heating of the plasma over long distances.

“In this new study, we addressed an important question that has not been investigated in the existing literature,” Ayaz said. “By comparing our analysis with data from NASA’s Parker Solar Probe and the European Space Agency’s Solar Orbiter mission, we found strong consistency that validates our theoretical results. In particular, this study It represents the first investigation of these phenomena in a thermal plasma and represents a major advance in our understanding of KAW dynamics in the solar corona and solar wind.”

need for speed

Group velocity, the speed at which wave energy propagates through a medium, is important to KAW in understanding how energy is transported across the various spatial regions that are central to Ayaz’s research, such as the solar corona and solar wind. is an important element. This speed will help researchers examine the flow and distribution of wave energy, allowing them to better understand its role in energy transfer in astrophysical environments.

One key piece of the puzzle is the exact velocity of the particle (called the resonant velocity) after it acquires energy from a wave such as the KAW.

“How fast does a particle move when it absorbs energy from a KAW? Resonant velocity provides important insight into the flow and distribution of particle acceleration, and the role of particles in energy transfer in astrophysical environments. ,” says Ayaz.

“Our current research derives an analytical expression for the particle’s net resonant velocity, providing a quantitative measure of the particle’s acceleration. In the new study, we derive an analytical expression for the particle’s net resonant velocity, which is derived from the distance that these waves can travel. We also reveal the decay length of KAW, a parameter.” Observing the energy before decay provides valuable insight into the efficiency and reach of energy transfer through KAW in space plasmas. ”

All three aspects, the group velocity of the KAW, the net resonant velocity of the particles, and the decay length of the KAW, play a crucial role in understanding wave-particle interactions in space plasmas.

“The phenomenon of a particle’s net resonance velocity stands out as particularly important,” Ayaz says. “This is to directly quantify how particles gain energy from the KAW and how their motion evolves in response to this energy transfer. For the first time, we We derived generalized analytical expressions for resonance velocities and provided a robust framework to understand the mechanisms of particle acceleration and heating in nonthermal plasmas, both local and large-scale in the solar corona and solar wind. provides insight into both the dynamics of ”

“Said conducted extensive and highly important research into the direct mechanisms by which ions, particularly protons, are heated by magnetic fluctuations that terminate cascades of energy from large to small scales,” said Aerojet. / said Dr. Gary Zink, Rocketdyne Chairman. Director of the Center for Space Science, Astrophysics and Aeronautics Research (CSPAR).

“KAW has long been thought to be a mechanism by which small-scale magnetic energy is converted to heat, but the exact mechanism by which this process occurs was not understood. Syed’s research It provides a clear path to how the process occurs.”

Looking ahead, this innovative work lays the foundation for future research projects aimed at improving our understanding of the complex processes taking place in the space plasma environment.

“The derived equations are of great practical value to the broader scientific community, especially data simulation experts,” Ayaz concludes. “By incorporating these generalized formulas into a coding framework, researchers can simulate more accurate models of wave-particle interactions and improve predictions of space weather events.

“This interdisciplinary applicability highlights the potential of our discoveries to advance not only theoretical plasma physics, but also practical applications in computational astrophysics and beyond.”