The Sun's Surface Is Covered in 12-Mile Whirlpools That No Telescope Could Resolve Until Now

Astronomers using the NSF Daniel K. Inouye Solar Telescope in Hawaii have found a structure on the Sun that nobody has been able to see before: tiny plasma vortices, about 20 kilometers — roughly 12 miles — across, curling along the boundaries between the convection cells that tile the solar surface.

Twenty kilometers is nothing on a star 1.4 million kilometers wide. Resolving it required the largest solar telescope ever built, observing at a wavelength of 416 nanometers, and produced the highest-resolution images of the solar photosphere ever recorded. "To detect the vortices, we needed to resolve structures on the solar surface about 20 kilometers (12 miles) in size," said Michiel van Noort of the Max Planck Institute for Solar System Research, one of the researchers on the study. That figure sits essentially at the physical limit of what current instruments can do.

The vortices appear at the edges of granules — the convection cells that give the Sun's surface its grainy, boiling appearance. Granules are between 500 and 2,000 kilometers across, each one a column of hot plasma rising in the middle, spreading outward, cooling and sinking at the rim. The new structures form in the shear zones where a rising cell slides past the sinking material at its border, and they look strikingly like breaking ocean waves. That resemblance is not decorative: the team attributes the vortices to Kelvin–Helmholtz instabilities, the same fluid-dynamical process that curls the crest of a wave or the edge of a cloud layer.

The work was a collaboration between the NSF National Solar Observatory, the Max Planck Institute for Solar System Research in Germany and the High Altitude Observatory, with David Kuridze as lead author. The results were published in Nature. Sami K. Solanki, director of the Max Planck institute, was among the contributors.

The reason this matters goes beyond a new item in the catalogue of solar features. The Sun's magnetic field is frozen into its plasma, so anything that twists the plasma twists the field. If billions of these small vortices are spinning continuously across the entire surface, they represent a mechanism for winding magnetic field lines and pumping magnetic energy upward into the chromosphere and corona.

That has a bearing on two of the oldest unsolved problems in solar physics: why the corona is hundreds of times hotter than the surface beneath it, and why the Sun's magnetic activity flips on an 11-year cycle that is fast compared with what simple dynamo models predict. Efficient small-scale energy transport of the kind these vortices could provide would help with both. Confirming that requires tracking how many there are, how long each lives, and how much magnetic flux each one actually carries — measurements the Inouye telescope is now in a position to make.