Scientists capture highest-resolution images of Sun's surface, revealing plasma vortices

Highest-resolution solar surface images

Scientists using the Daniel K. Inouye Solar Telescope on Maui, Hawaii, have captured the highest-resolution images ever obtained of the Sun's visible surface, or photosphere. The study, published in Nature on Wednesday, was conducted by researchers from the NSF National Solar Observatory (NSO), the Max Planck Institute for Solar System Research (MPS) in Germany, and the High Altitude Observatory (HAO) in the United States. The images reveal swirling, vortex-like patterns of hot plasma continuously growing and rotating across the solar surface, with diameters ranging from about 19 km, the minimum scale detectable by the telescope, up to roughly 170 km. Some structures are smaller than 20 km across; distinguishing them is comparable to spotting a one-euro coin from 180 km away. The photosphere itself is a relatively thin layer, about 100 km in depth, compared to the overall solar diameter of roughly 1.4 million km.

Kelvin-Helmholtz instability on a star

The researchers identified the vortices as the first detection of Kelvin-Helmholtz instability (KHI) on the surface of a star. KHI, first described in the 19th century, occurs when two parallel streams of fluid or gas move at different velocities, generating perturbations that grow into wave-like vortices until they break apart. The phenomenon has been observed in Earth's oceans and clouds and in the atmospheres of Jupiter and Saturn, but never before at this level of detail on the Sun.

The interface can become unstable and develop wave-like vortices that grow in size until they break apart, not unlike waves out on a lake or out on the ocean in windy conditions.

Wöger, a senior scientist at the NSF's National Solar Observatory in Colorado and the Inouye telescope's instrument program scientist, is co-lead author of the study. The observations were originally made to test and refine the telescope's limits, but the researchers realized they had photographed the Sun's bright outer layer at a resolution never before achieved.

Energy storage and magnetic fields

According to current theory, the Sun accumulates energy when magnetic field lines twist, similar to mechanical energy stored in a spring. This creates an unstable magnetic field architecture: the stored energy can be released suddenly through magnetic reconnection, where twisted field lines open and reconnect. The mechanism responsible for the twisting of magnetic field lines was previously unclear. The newly discovered vortices, which appear to form constantly wherever the magnetic field is sufficiently intense, could be the driving force that regularly triggers this twisting.

My first reaction was: 'Wow, how is it possible to see such small and such fine structures on the Sun?' This is something we had never observed before.

Implications for space weather

Understanding these processes has practical consequences for Earth. Solar flares and coronal mass ejections can trigger geomagnetic storms capable of disrupting satellites, GPS navigation, power grids, and global communications. The swirling motions produce magnetic energy that accumulates and can later fuel large-scale solar explosions.

We want to understand the physics of the Sun down to the smallest scales so that we can better predict space weather.

Boboltz, of the National Solar Observatory, noted that the Sun is the source of all energy and space weather affecting Earth. The higher-resolution images will help scientists understand and eventually forecast space weather more accurately. Solar physicist Ruizhu Chen of Stanford University, who was not involved in the research, compared the patterns to Vincent van Gogh's 1889 painting "The Starry Night."