The sun's violence is written on its own face, though the place where it begins lies hidden above in the corona. A team led by Marcel Corchado Albelo has learned to read the bright, fractured ribbons that flares leave on the chromosphere as footprints of that unseen work. Using observations of a 2015 M6.5 flare, they found that energy arrives in bursts and fragments, with the ribbons growing more intricate as magnetic reconnection speeds up. The discovery does not yet tell us when the next storm will come, but it gives physicists a clearer view of how the sun lets go of its stored magnetic ten
Flare Ribbons Offer a Window Into Hidden Solar Explosions
Visible patterns below offer clues to difficult-to-observe processes above.
Mark
Why look at ribbons at all? Why not just watch the flare?
Mimi
Because the explosion starts in the corona, and the sun's glare hides it. The ribbons are where the energy lands in the chromosphere, and that part is bright and visible.
Mark
So the ribbons are a kind of footprint.
Mimi
Yes. Plasma and high-energy particles crash back down along magnetic field lines, and the shape they leave carries information about what happened above.
Luke
Careful, though. They tested one flare, an M6.5 from June 2015. That's a single event, not a survey of flares.
Mimi
Fair. The paper calls it a first step, and the model was first checked against synthetic observations before the real flare.
Mark
What did they actually find?
Mimi
Energy arrives in bursts, with the ribbon breaking into fragments of different sizes. And complexity rose with the reconnection rate.
Luke
That matches what simulations predicted, but the corona itself is still not seen directly. The ribbon is a proxy, as the authors say.
Mark
Does this help predict flares?
Mimi
Not on its own. It should improve models of how flares release energy.
Luke
Which is a more modest claim than forecasting, and the source is clear about that.
El Pulso
- Magnetic fields on the sun twist until they can no longer hold, then snap and reconnect, unleashing flares that can disrupt radio, GPS, and power grids on Earth.
- The site of that release sits in the corona, a region hidden by the sun's glare, so scientists have been working without a direct window.
- Researchers turned to flare ribbons, the bright footprints where energetic particles strike the chromosphere, and measured how their shapes break apart.
- Data from a June 2015 M6.5 flare captured by the IRIS satellite showed energy landing in fragmented bursts, with complexity rising alongside reconnection rate.
- The findings give models a long-awaited observational test, though they will refine understanding of flares rather than improve near-term forecasts.
The sun's violence is written on its own face, though the place where it begins lies hidden above in the corona. A team led by Marcel Corchado Albelo has learned to read the bright, fractured ribbons that flares leave on the chromosphere as footprints of that unseen work. Using observations of a 2015 M6.5 flare, they found that energy arrives in bursts and fragments, with the ribbons growing more intricate as magnetic reconnection speeds up. The discovery does not yet tell us when the next storm will come, but it gives physicists a clearer view of how the sun lets go of its stored magnetic tension.
The sun does not keep its violence to itself. A strong flare can send a coronal mass ejection toward Earth, painting the sky with auroras, and it can also black out radio, scramble GPS, disturb spacecraft electronics, and strain power grids. Flares are the most powerful explosions in the solar system, graded by X-ray brightness from A to X, and their energy rivals millions of hydrogen bombs detonated at once.
The cause is magnetic. Fields in the sun are continually twisted until they snap and reconnect into a simpler arrangement, and that release is the flare. The difficulty is that the process begins in the corona, which the sun's glare hides from view.
A new paper in The Astrophysical Journal, led by Marcel Corchado Albelo, takes an indirect path. It studies flare ribbons, the footprints left as plasma and particles strike the chromosphere along magnetic field lines, and asks whether their fine structure reveals what happens above. The team built a quantitative method, tested it on synthetic data, and then applied it to an M6.5 flare from June 22, 2015, seen by the IRIS satellite.
The flare did not release its energy smoothly. The ribbon broke into fragments and delivered energy in bursts, and its complexity grew with the reconnection rate. Corchado Albelo called it the first experimental link between these irregular shapes and the structure of the energy conversion region. His co-author Maria Kazachenko noted that simulations had predicted such behavior for years without observational confirmation, and that the method borrowed its tools from another field.
The authors suggest ribbon complexity can serve as a proxy for current-sheet fragmentation in the corona. The work will not forecast flares by itself, but it deepens our understanding of how the sun releases its energy and should sharpen the models that future forecasting depends on.
The sun does not keep its violence to itself. When a solar flare is powerful enough, the coronal mass ejection that comes with it can reach Earth and paint the sky with auroras. It can also do harder things: black out radio, throw off GPS, upset electronics on spacecraft and strain power grids.
Flares are the most powerful explosions in the solar system. Astrophysicists grade them by X-ray brightness in five classes, A, B, C, M and X, from weakest to strongest, with each letter marking a tenfold jump in energy output. The energy released is comparable to millions or even billions of hydrogen bombs going off at once, and it exceeds both a supervolcano eruption and the asteroid impact that ended the dinosaurs.
The cause is magnetic. The sun's magnetic fields are constantly twisted and rotated, until they can no longer hold and snap, then reconnect into a simpler, more stable arrangement. That process, called reconnection, frees energy from its magnetic restraints and releases it as a flare.
The trouble for researchers is that flares begin in the corona, the sun's outermost layer, which is hidden by the sun's glare and hard to observe. A new paper in The Astrophysical Journal takes a different route. Titled "Evolution of Spatial Complexity in Flare Ribbon Substructure and Its Relationship to Magnetic Reconnection Dynamics," it is led by Marcel Corchado Albelo of the U.S. National Science Foundation, who is also an ambassador for the Daniel K. Inouye Solar Telescope.
The team looked at flare ribbons, which work something like a flare's footprints. They are made of plasma and high-energy particles that slam back into the sun during reconnection, following magnetic field lines. When they hit the chromosphere, they light up brilliantly. Recent three-dimensional flare models had suggested that fine structure in these ribbons is tied to the fragmentation of the reconnecting current sheet in the corona. If so, the ribbons could serve as a diagnostic tool for what is happening up there.
The researchers developed a way to quantify how the ribbons and their substructure evolve, using small details of the places where energy lands in the chromosphere. They built a model and tested it on synthetic observations, then applied it to a real event: an M6.5-class flare on June 22, 2015, observed by the Interface Region Imaging Spectrograph, or IRIS, a solar observation satellite launched in 2013.
The flare did not deliver its energy smoothly or uniformly. Rather than one large event, the ribbon broke into fragments of different sizes and deposited energy in bursts. Ribbon complexity increased with the reconnection rate.
"For the first time we have experimentally shown a physical relationship between the irregular shapes we observe and the structure of the energy conversion region," Corchado Albelo said in a press release. Maria Kazachenko, a co-author and National Solar Observatory scientist, noted that simulations had suggested for years how ribbon boundaries should behave, but observations had never confirmed it. This work, she said, provided a quantitative observational test, using a tool adapted from a completely different field. She also advises Corchado Albelo's graduate work and credited the persistence and creativity of a graduate student.
The authors conclude that the buildup of ribbon complexity across multiple spatial scales can serve as an observational proxy for current-sheet fragmentation in the corona. They call the analysis a first step toward linking ribbon shape to reconnection dynamics quantitatively.
The work will not forecast flares on its own. Its contribution is to explain how flares release their energy and to feed better models of flaring.
Citas Notables
For the first time we have experimentally shown a physical relationship between the irregular shapes we observe and the structure of the energy conversion region.— Marcel Corchado Albelo, lead author
In this work, for the first time, we provided a quantitative observational test of those simulations.— Maria Kazachenko, co-author, National Solar Observatory
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