The Daniel K.
A nice M4.52 solar flare is ongoing around AR 4197. This is one of the strongest solar flares in the last couple months, and I would not be surprised if we see us crossing the >M5 threshold at least once in the next 24 hours. pic.twitter.com/PfwmFb2u6B
— Vincent Ledvina (@Vincent_Ledvina) August 26, 2025
Inouye Solar Telescope has captured the highest-resolution images of a solar flare at the H-alpha wavelength on August 8, 2024. The images reveal dark coronal loop strands with exceptional clarity.
This breakthrough could redefine the fundamental scale of solar coronal loops and enhance flare modeling.
Multiple flares are now ongoing from around AR 4191 (C9.1) and our incoming active region on the Sun's eastern limb (M1.9 from ex AR 4170).
We are about to have some Chatty Cathy's on the Earth-facing disk. Let's get some CMEs, now! pic.twitter.com/rpUWIVDDI8
— Vincent Ledvina (@Vincent_Ledvina) August 23, 2025
The study, titled “Unveiling Unprecedented Fine Structure in Coronal Flare Loops with the DKIST,” is available in The Astrophysical Journal Letters. Coronal loops are plasma arches that follow the sun’s magnetic field lines and trigger sudden energy releases, fueling solar storms that affect Earth’s infrastructure.
🚨 Big firsts for the @NSF Inouye Solar Telescope: X-class flare, sharpest H-alpha flare image, and smallest coronal loops ever imaged. These observations may help reveal coronal loop scales and improve flare modeling, aiding space weather forecasts. https://t.co/giALaNywSQ pic.twitter.com/kDjzXG5HBG
— National Solar Observatory (@NatSolarObs) August 25, 2025
Cole Tamburri, the study’s lead author and a Ph.D. candidate at the University of Colorado Boulder, emphasized the significance of this observation. It was the first time the Inouye Solar Telescope had observed an X-class flare under ideal conditions. A high-speed, high-resolution movie of the flare captured by the Inouye Solar Telescope showcases both bright ribbons and dark overlying coronal loops, revealing previously unseen details.
The Inouye’s Visible Broadband Imager (VBI), tuned to the H-alpha filter, achieves a resolution down to approximately 24 km, more than twice as sharp as the next-best solar telescope.
Capturing unprecedented solar flare details
The research involved scientists from the National Solar Observatory (NSO), the Cooperative Institute for Research in Environmental Sciences (CIRES), and the Laboratory for Atmospheric and Space Physics (LASP).
The team concentrated on the magnetic field loops, averaging about 48 km in width, with some at the resolution limit of the telescope. “Before Inouye, we could only imagine what this scale looked like,” Tamburri said. “Now we can see it directly.
These are the smallest coronal loops ever imaged on the sun.”
Maria Kazachenko, a co-author of the study, described the leap in resolution as exhilarating, emphasizing how the findings surpassed initial research objectives. The VBI data revealed ultra-fine coronal structures that can inform more accurate flare models. The imagery features dark, thread-like loops arching in a glowing arcade, with bright flare ribbons appearing in sharp relief.
This detailed view provides new insights into the shapes, evolution, and fundamental building blocks of flare architecture. “It’s a landmark moment in solar science,” Tamburri concluded. “We’re finally seeing the sun at the scales it works on.”
For more information, refer to the study in The Astrophysical Journal Letters.
