Imagine you could feel the sun's surface at about 5,500 degrees Celsius and then travel just past it into the corona—the sun's outer atmosphere—and suddenly feel temperatures jump to over a million degrees. That happens, and scientists have never fully understood why. Now, a University of Alabama in Huntsville researcher named Syed Ayaz thinks tiny cosmic dust grains might hold the answer.
Ayaz, a graduate research assistant, used data from NASA's Parker Solar Probe to study how energy moves through the solar corona. His findings, published in The Astrophysical Journal, show that dust grains floating near the sun can change how plasma waves carry heat through space. Those plasma waves are important because they transport energy that heats the corona to millions of degrees—much hotter than the sun's surface itself.
"The higher temperature of the sun's corona remains one of the major unsolved problems in heliophysics," Ayaz explained. "Dust grains were not usually considered an active part of coronal heating models because they were not expected to survive the high temperature."
But here's the surprising part: dust does survive, and it's doing more than just sitting there. When tiny dust grains slam into the Parker Solar Probe at high speeds, they vaporize and create charged particle clouds that show up as voltage spikes in the spacecraft's FIELDS instrument. This means the entire spacecraft acts like an accidental dust detector, revealing that dust exists and behaves actively much closer to the sun than scientists expected.
"What surprised me most was that the PSP could reveal so much about dust, even though it does not carry a dedicated dust detector on board," Ayaz noted.
The study shows dust affects energy transport in two competing ways—sometimes dust mass dominates, sometimes dust charge dominates. Dust grains are about a million times more massive than electrons or ions, so they interact powerfully with electric and magnetic fields around the sun. These interactions modify how kinetic Alfvén waves—key carriers of energy through space plasmas—travel and dissipate.
Ayaz's supervisor, Dr. Gary Zank, director of the Center for Space Plasma and Aeronomic Research at UAH, called the discovery groundbreaking. "The results already suggest that a surprising new paradigm may be emerging," Zank said. "Syed has done outstanding work that will have a significant impact on understanding the physics of the solar corona."
The Parker Solar Probe launched in 2018 and has been flying closer to the sun than any previous spacecraft. Its observations continue to rewrite what scientists thought they knew about our star's behavior.