Key facts
- The Daniel K. Inouye Solar Telescope has captured images of Kelvin-Helmholtz instabilities on the Sun's surface.
- These vortex-like structures were previously too small to be observed by telescopes with mirrors smaller than 2 meters.
- The observations were made at a wavelength of 416 nanometers, achieving a spatial resolution of about 19 kilometers.
- The vortexes measure between 25 and 170 kilometers in diameter and can double in size in under a minute.
- The presence of these instabilities may alter current models of how heat, mass, and magnetic energy move through the Sun's atmosphere.
For decades, scientists have theorized that the same Kelvin-Helmholtz instability that causes ripples on water and shear in clouds must also occur with plasma on the Sun's surface. However, these solar vortexes were previously too small to be observed by telescopes with mirrors smaller than 2 meters.
The Daniel K. Inouye Solar Telescope, the world's largest solar telescope with a 4-meter mirror, has now provided the first direct observations of these phenomena. During a test run on April 14, 2025, a team led by David Kuridze and Friedrich Wöger of the National Solar Observatory pointed the telescope at an active region on the Sun.
Using a diagnostic camera setup, they recorded images at a wavelength of 416 nanometers. The goal was to achieve diffraction-limited performance, pushing the limits of the telescope's optics and compensating for atmospheric blurring. The resulting images, with a spatial resolution of about 19 kilometers, revealed structures never seen before.
These structures were identified as vortex-like formations and fine dark striations at the interfaces between concentrated magnetic fields and the surrounding granulation. The team found 47 such interfaces, with vortexes measuring 25 to 170 kilometers in diameter. They observed that these vortexes could double in size in under a minute and propagate at speeds of 0.67 to 3 kilometers per second.
The formation of these curls is linked to the direction of the magnetic field. When magnetic field lines run across the flow of plasma, they do not suppress the instability, allowing the vortexes to form and grow. The researchers confirmed their observations through computer simulations that accurately reproduced the appearance and dynamics of the vortexes.
The discovery of these previously hidden instabilities suggests a stirring mechanism where none was expected, potentially altering how heat, mass, and magnetic energy are transported through the Sun's atmosphere and influencing models of solar convection.