The largest solar telescope on the planet, the Daniel K. Inouye, has managed to record plasma vortices on the surface of the Sun, a phenomenon that, although predicted by science, was invisible until now due to its tiny size. This discovery, made on April 14, 2025, brings a new look at the star’s dynamics.
The concept of Kelvin-Helmholtz instability describes how the boundary between two fluids sliding at different speeds bends and forms eddies. This physics, understood since the end of the 19th century, explains everything from the ripples in the water caused by the wind to the curved shapes of clouds.
For decades, scientists have theorized that the same process should occur with solar plasma, but without the ability to confirm it visually. Now, a team of researchers led by David Kuridze and Friedrich Wöger, both from the National Solar Observatory, has validated the occurrence of these vortices, which have turned out to be ubiquitous. The study suggests that this revelation could redefine understanding of how heat, mass and magnetic energy propagate in the Sun’s atmosphere.
The ability of the world’s largest solar telescope to observe
The difficulty in observing these plasma vortices on the Sun has always been linked to their small size, which required an optical resolution capacity that telescopes with mirrors smaller than 2 meters were unable to offer. This limitation prevented detection for much of the history of solar physics, until the United States National Science Foundation opened the Daniel K. Inouye Solar Telescope, a 4-meter instrument located in Hawaii and considered the largest solar telescope in the world, which began operations in November 2021.
In a period of just three minutes, on April 14, 2025, Kuridze’s team trained the telescope on an active area near the center of the solar disk. They recorded images using a wavelength of 416 nanometers, using a diagnostic camera system developed in collaboration between the National Solar Observatory and the Max Planck Institute for Solar System Research. Initially, the focus of the mission was not the search for vortices. “Our main goal was to achieve resolution-limited performance by the diffraction of the telescope,” Kuridze explained.
The diffraction limit is the maximum detail that a telescope’s optics can capture, being influenced by the size of the mirror and the observed wavelength. A larger mirror and shorter wavelength allow you to see finer details. With Inouye’s mirror set at 4 meters, the team sought to optimize the wavelength. “We chose 416 nanometers, which is at the lower end of the visible spectrum, to obtain a higher diffraction limit and resolution,” Kuridze said.
What the team achieved went far beyond a simple test. The camera captured images at a speed of 740 frames per second, with exposures of 100 microseconds. Two thousand of these frames were then combined into a final image using a technique known as blind multi-frame deconvolution, which models and corrects the blur caused by the Earth’s atmosphere after the action of the telescope’s optics. The result was a record of the solar surface, with a new image every two seconds and a spatial resolution of approximately 19 kilometers, precisely at the theoretical limit achievable by a 4-meter mirror at this wavelength.
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“As a result, we achieved unbelievable observations, which allowed us to see something unprecedented,” said Kuridze.
Identification and characteristics of new solar vortex structures
In the 416 nanometer range, the solar surface is dominated by granules, which are convection cells that transport heat from the Sun’s interior, interspersed by concentrated beams of intense magnetic fields. In low-resolution photographs, the transition area between a magnetic beam and the surrounding grain appears homogeneous and slightly blurry.
However, data collected by the Daniel K. Inouye Telescope (DKIST) presented a very different reality. The boundaries are almost entirely made up of vortex-like structures and thin, dark streaks. The team was able to identify 47 of these areas with vortices in the telescope’s field of view, measuring the distance between them. The distance varied between 60 and 100 kilometers, with individual vortices measuring 25 to 170 kilometers in diameter. The smallest patterns detected were exactly at the resolution limit of 19 kilometers, which indicates that their actual minimum size is still unknown. By observing the growth rate, the researchers noted that the vortices can double in size in less than a minute and propagate along the interfaces at speeds between 0.67 and 3 kilometers per second.
According to Kuridze, the perception of an observer flying over one of these borders would depend on the moment of arrival. Instability develops in two phases. “Initially, there is a linear phase, where everything is more peaceful, organized, regular and beautiful,” he explained. “Looking closely, it will look something like moving clouds.” The peaceful phase, however, is followed by chaos. “At some point, everything evolves into a non-linear regime, and things become complex,” Kuridze added. “Basically, turbulence arises — quite chaotic turbulence.”
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The formation of these ripples specifically at the interfaces is related to the direction of the magnetic field. Magnetic lines behave like elastic threads that pass through the plasma and oppose deformation. If these threads are aligned with the flow direction, they pull on any ripples at the boundary, flattening them and preventing the instability from growing. However, if the lines cross the flow, there is no impediment to the formation of vortices.
In the regions of intense magnetic field that were observed by DKIST, the magnetic field projects almost vertically from the surface, while the adjacent granular flows move laterally. The arrangement of the filaments is inadequate to keep the boundary stable, allowing the spirals to develop without restriction.
Scientific confirmation and simulations that validate the data obtained
Faced with an unprecedented discovery, Kuridze, Wöger and their collaborators had to ensure that the observations were not just a result of image processing. “Everything pointed to it being Kelvin-Helmholtz, but that wasn’t enough, of course,” Kuridze said. “It is essential to have theoretical proof to ensure that this phenomenon really is the case.”
To obtain this theoretical validation, scientists carried out computer simulations. They modeled an area of the photosphere measuring approximately 6 megameters on a side, on a grid spaced 3.2 kilometers apart, using as a reference a map of the magnetic field of the observed region. They then synthesized images that DKIST should have captured when observing this simulated area.
The team calculated 500 spectral points within the examined wavelength range, applying the transmission profile of the real interference filter and adjusting the result to match the telescope’s resolution. The synthetic images accurately reproduced the appearance and dynamics of the vortices, including their growth rate, distribution and propagation speeds. This process led the team to the conclusion that their observations are most likely authentic, and their implications are significant.
Impact of discoveries on understanding the solar atmosphere
A robust magnetic field generally keeps the plasma in a steady state. A sunspot, for example, is an area where the field strength is sufficient to suppress convection, resulting in a darker, cooler surface.
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The discovery of an instability that creates vortices at the edges of each magnetic element indicates the existence of a shaking mechanism in places where it was not expected. This implies that magnetized and unmagnetized gas can mix, and cooler material from the edges of convection cells can infiltrate the magnetic regions. This interaction changes the way heat is transferred just below the visible surface, an aspect that is not considered in current models of solar convection.
Another affected area is the solar corona, the outer layer of the Sun with temperatures of millions of degrees. Partial heating of the corona occurs due to the rearrangement of magnetic field lines at their anchor points, which intertwine into complex tangles and eventually release energy. The challenge was that the exact mechanism behind this rearrangement had never been directly observed. Kuridze points out that “there are these torsional movements over the entire surface of the magnetic element, and this torsional movement is nothing more than the intertwining of the magnetic fields.”
However, it is important to consider that, so far, these results are based on an observation window of just three minutes — a punctual record, and not a comprehensive survey — and on simulations that still have certain limitations.
Challenges and future directions in solar vortex research
“One of the things we don’t yet know is how small these Kelvin-Helmholtz patterns might be on the Sun,” Kuridze said. What we can resolve is very close to the telescope’s resolution limit, which indicates that even smaller patterns may be being missed. To get around this issue, one approach would be to allow simulations to operate at a resolution higher than what the telescope can observe. However, the team has had limited success in this attempt to date.
“When running simulations at higher resolutions, it is necessary to incorporate additional principles of physics, and we are not entirely sure exactly how things work in computer simulations when aiming to reach these resolutions,” he explained. “This is a completely new area, and requires further investigation.”
An additional limitation is related to the type of data collected by DKIST, which focused mainly on high-resolution visual images. Although these images offered a good estimate of the location and strength of the magnetic fields, they were still an approximation. All of the team’s knowledge about the actual speed of plasma movement comes from simulations, not directly from the telescope, and the magnetic field that drives the entire process has never been measured directly on this scale.
The research team believes that most of the remaining uncertainties can be resolved by extending observations beyond the current three-minute window. “To quantify how the magnetic field evolves over time, how much energy is dissipated, how much energy is released and what energy budget is available for eruptions and flares, much longer observations and detailed magnetic maps are needed,” concluded Kuridze. “That’s our next challenge and our next milestone.”