Unprecedented Solar Imaging Reveals Fine Magnetic Stripes Influencing Space Weather

Sharpest-ever solar view reveals tiny stripes driving big space storms

A remarkable advancement in solar physics has emerged, showcasing ultra-fine magnetic structures on the Sun’s surface, made possible by the NSF’s Daniel K. Inouye Solar Telescope. Researchers have captured unprecedented images of narrow magnetic stripe-like features, known as striations, within solar granules. These structures behave like magnetic curtains that ripple across the Sun, reshaping our understanding of magnetic field dynamics at microscopic scales. With an impressive resolution of just 20 kilometers, scientists have successfully correlated real observations with simulations, uncovering subtle magnetic fluctuations that affect our perception of the solar surface. These findings not only enhance our understanding of solar activity but also inform magnetic behaviors in distant cosmic environments, which could aid in predicting space weather on Earth.

A team of solar physicists has published a new study highlighting the fine-scale structure of the Sun’s surface. Utilizing the unmatched capabilities of the U.S. National Science Foundation (NSF) Daniel K. Inouye Solar Telescope, located at the NSF National Solar Observatory in Maui, scientists have observed, for the first time in such detail, ultra-narrow bright and dark stripes on the solar photosphere. This breakthrough offers unprecedented insight into how magnetic fields influence solar surface dynamics at scales as small as 20 kilometers (approximately 12.4 miles).

The resolution achieved allows researchers to link these stripes to those observed in advanced simulations, enhancing our understanding of their nature. These striations, seen against the walls of solar convection cells known as granules, are generated by curtain-like sheets of magnetic fields that shift like fabric in the wind. As light from the hot granule walls interacts with these magnetic “curtains,” it creates a pattern of alternating brightness and darkness, reflecting variations in the underlying magnetic field. If the field is weaker within the curtain than its surroundings, it appears dark; if it’s stronger, it appears bright.

“In this work, we investigate the fine-scale structure of the solar surface for the first time with an unprecedented spatial resolution of about 20 kilometers, or the length of Manhattan Island,” explains NSO scientist Dr. David Kuridze, the lead author of the study. “These striations are the fingerprints of fine-scale magnetic field variations.”

The results of this study were unexpected and could only be achieved due to the remarkable capabilities of the Inouye Solar Telescope. The team utilized the telescope’s Visible Broadband Imager (VBI) instrument operating in the G-band, a specific range of visible light particularly effective for studying the Sun. This range highlights areas with strong magnetic activity, making features like sunspots and fine-scale structures easier to detect. The telescope allows researchers to observe the solar photosphere at an extraordinary spatial resolution better than 0.03 arcseconds, which is the sharpest ever recorded in solar astronomy.

To interpret their observations, the team compared the images with advanced simulations that model the physics of the Sun’s surface. The study confirms that the striations are signatures of subtle yet powerful magnetic fluctuations—variations of merely a hundred gauss, comparable to the strength of a typical refrigerator magnet—that influence the density and opacity of the plasma, causing shifts in the visible surface by just a few kilometers. These shifts, known as Wilson depressions, are detectable solely due to the unique resolving power of the 4-meter primary mirror of the NSF Inouye Solar Telescope, the largest in the world.

“Magnetism is a fundamental phenomenon in the universe, and similar magnetically induced stripes have also been observed in more distant astrophysical objects, such as molecular clouds,” states NSO scientist and study co-author Dr. Han Uitenbroek. “Inouye’s high resolution, combined with simulations, enables us to better characterize the behavior of magnetic fields across a broad astrophysical context.”

Understanding the magnetic architecture of the solar surface is crucial for comprehending the most energetic events in the Sun’s outer atmosphere—such as flares, eruptions, and coronal mass ejections—and thus improving space weather predictions. This discovery not only deepens our understanding of this architecture but also paves the way for studying magnetic structures in other astrophysical contexts and at small scales previously deemed unattainable from Earth.

“This is just one of many firsts for the Inouye, demonstrating how it continues to push the boundaries of solar research,” remarks Dr. David Boboltz, NSO Associate Director for the NSF Inouye Solar Telescope. “It also highlights Inouye’s essential role in understanding the small-scale physics that drive space weather events affecting our increasingly technological society here on Earth.”

The paper detailing this study, titled “The striated solar photosphere observed at 0.03” resolution,” is published in The Astrophysical Journal Letters.