National Solar Observatory confirms Kelvin-Helmholtz instabilities on the Sun

Astronomers led by David Kuridze and Friedrich Wöger from the National Solar Observatory have successfully observed Kelvin-Helmholtz instabilities driving plasma mixing on the Sun. This phenomenon, mathematically described by Lord Kelvin and Hermann von Helmholtz nearly 150 years ago, had remained unobserved due to the small scale of the structures involved.

Using the Daniel K. Inouye Solar Telescope (DKIST) in Hawaii—the world’s first solar telescope with a 4-meter mirror—researchers achieved a resolution of approximately 19 km on the solar surface. Observations of an active region near a sunspot revealed that the boundaries between hot convective cells and magnetic field clusters are filled with vortices and striated structures rather than being smooth.

The team analyzed 47 vortices, finding diameters ranging from 25 to 170 kilometers. Magnetohydrodynamic simulations matched the visual data, and consistency with Chandrasekhar’s linear theory confirmed the presence of Kelvin-Helmholtz instability. These vortices serve as an efficient mechanism for transporting mass and energy on the Sun.