To shed further light on this age-old mystery, Syed Ayaz, a Ph.D. candidate in the UAH Center for Space Plasma and Aeronomic Research (CSPAR), employed a statistical model known as a Kappa distribution to describe the velocity of particles in space plasmas, while incorporating the interaction of suprathermal particles with kinetic Alfven waves (KAWs).

KAWs are oscillations of the charged particles and magnetic field as they move through the solar plasma, caused by motions in the photosphere, the sun's outer shell. The waves are a valuable tool for modeling various phenomena in the solar system, including particle acceleration and wave-particle interactions.

"Our earlier work focused on how KAWs contribute to the sun's mysterious ability to heat its corona to over a million degrees despite the much cooler surface," Ayaz explains.

"Using the Cairns distribution function, we explored magnetic energy conversion, plasma transport and particle acceleration mechanisms in the solar corona. However, the Cairns distribution, while insightful, lacks a strong statistical foundation. In this new paper, we build upon our earlier findings by employing the Kappa distribution, which offers a statistically robust framework widely recognized in space plasma research."

In heliophysics, a Kappa distribution is a statistical model that describes the velocity distribution of particles in space plasmas, particularly in the solar wind. "By extending our work to this distribution," the researcher says, "we uncover new and fascinating details about solar coronal heating, particularly how KAWs facilitate energy transfer and particle acceleration."

"For the first time, Syed has provided a deep understanding of the role of energetic particles on the characteristics of kinetic Alfven waves, yielding important insights into the dissipation, and hence heating, of the coronal plasma by these important waves," says Dr. Gary Zank, Aerojet/Rocketdyne Chair in Space Science and director of CSPAR.

"KAWs represent the end point of energy transfer in a turbulent magnetized plasma and are a critical element in understanding how the corona reaches such high temperatures. This is an important step forward in understanding this longstanding problem about the sun's atmosphere."

When charged particles interact with wave electric fields in a plasma, KAWs can transfer energy to the particles, leading to plasma heating over extended distances.

"This new approach strengthens our understanding of the interplay between waves and particles, the mechanisms driving the solar wind and the corona's extreme temperatures," Ayaz notes. "The Kappa distribution allows us to incorporate the effects of suprathermal particles, which significantly influence wave-particle interactions and the dynamics of KAWs."

Suprathermal particles are charged ions and electrons found throughout interplanetary space that move at speeds up to hundreds of times faster than the thermal plasma of the solar wind.

"Our analysis highlights the influence of suprathermal particles alongside variations in the electron-to-ion temperature ratio and height relative to the solar radius of the sun," Ayaz says. "This comprehensive approach reveals how these parameters affect wave-particle interactions and energy dynamics in the solar corona."

In addition, the researcher's work complements the missions of both NASA's Parker Solar Probe and the ESA's Solar Orbiter.

"One of the most significant findings is our ability to address the observational gap left by NASA's Parker Solar Probe (PSP) and ESA's Solar Orbiter, which struggle to investigate the critical region within 10 solar radii," Ayaz says. "While the PSP's closest approach on December 24, 2024, partially explores this zone, our theoretical framework provides insights into Alfven wave behavior and their heating contributions in the uncharted 0-10 radii region.

"By bridging this gap, our study not only complements the observational data but also offers a predictive model for understanding wave dynamics and particle acceleration mechanisms in the solar corona, marking a significant step forward in solving the 'coronal heating problem.'"

Research Report:A study of particle acceleration, heating, power deposition, and the damping length of kinetic Alfven waves in non-Maxwellian coronal plasma

Related Links
The Center for Space Plasma and Aeronomic Research (CSPAR)
Solar Science News at SpaceDaily