Cosmic dust could play key role in cracking long-standing mystery of solar corona heating Robert Egan Senior Editor A researcher at The University of Alabama in Huntsville (UAH), a part of The University of Alabama System, has published a new study in The Astrophysical Journal suggesting that tiny charged dust grains near the sun may significantly influence how energy moves through the solar corona, the outer atmosphere of the sun. The discovery potentially rewrites how scientists understand why the corona is millions of degrees hotter than the surface of the sun itself. Conducted using data from NASA's Parker Solar Probe (PSP), the work shows that dust, long assumed to be largely irrelevant so close to the sun, can alter the behavior of key plasma waves that transport energy through space.

By changing how these waves travel and dissipate energy, dust may help determine where and how solar heating occurs in the corona and young solar wind. The study's lead author, Syed Ayaz, is a graduate research assistant in the UAH Center for Space Plasma and Aeronomic Research (CSPAR). "The discovery of dust in the young solar wind by Parker Solar Probe allowed Syed to open up an entirely new and unexpected area of study in solar physics," says Dr.

Gary Zank, distinguished professor of space science at UAH and CSPAR director. "This is very exciting, and Syed realized very quickly that the presence of dust could change how we view the long-standing and open problem of how to heat the solar corona to more than a million degrees. The results he obtained in his preliminary study already suggest that a surprising new paradigm may be emerging.

Syed has done outstanding work that will have a significant impact on understanding of the physics of the solar corona." The solar corona is a huge region of extremely hot, thin plasma that extends millions of kilometers into space and is much hotter than the surface, or photosphere, of the sun, which reaches only about 5,500°C (9,900°F), while the corona can reach 1–3 million°C or more. "The higher temperature of the sun's corona remains one of the major unsolved problems in heliophysics," Ayaz explains. "For decades, researchers have focused mainly on how electrons, ions, magnetic fields and plasma waves transport and dissipate energy in the solar atmosphere.

Kinetic Alfvén waves are especially important because they can carry electromagnetic energy through the corona and transfer that energy to particles, helping to heat and accelerate the plasma." What sets the new study apart is the introduction of dust grains into models that have traditionally treated the near-sun environment as only a mix of electrons, ions and magnetic fields. "Our work adds a new ingredient to this picture: dust grains," Ayaz says. "Before the Parker Solar Probe, dust was not usually considered an active part of coronal heating models because dust grains—a million times more massive than electrons/ions—were not expected to survive the high temperature of the solar corona." Instead, data from the PSP revealed something unexpected: dust is still present and active far closer to the sun than previously thought.