Researchers at NorthWest Research Associates have identified new signals from the sun’s atmosphere that may help predict when the next solar flare will occur.
Using data from NASA’s Solar Dynamics Observatory (SDO), the team found signals in the upper layers of the Sun’s atmosphere – the corona – that could help predict which regions of the Sun will trigger a solar flare. They found that above the regions about to ignite, the corona emits small flashes that look like small sparklers before a big firework display.
What is a solar flare?
Solar flares are huge, energetic bursts of light and particles from the Sun that occur when energy stored in twisted magnetic fields is released. Solar flares heat material to millions of degrees in just minutes, producing a burst of radiation across the electromagnetic spectrum—from radio waves to X-rays and gamma rays.
The three categories of solar flares are classified based on their brightness and X-ray wavelength: X-class flares (the largest), M-class flares (medium-sized), and C-class flares (the smallest). Solar flares can affect Earth in several ways, causing auroras, endangering astronauts, disrupting radio communications and causing major power outages worldwide.
How can analyzing the solar corona improve predictions?
Previous studies have explored how the lower layers of the Sun’s atmosphere, including the photosphere and chromosphere, can help predict solar flare activity in active regions typically marked by sunspots, or strong magnetic regions on the Sun’s surface that appear darker and cooler. However, the study of the corona takes predictions to new heights.
KD Leka, the lead author of the study and an appointed foreign professor at Nagoya University in Japan, explained: “We can get very different information in the corona than we get from the photosphere or ‘surface’ of the Sun. Our results can give us a new marker to distinguish which active regions are likely to erupt soon and which will remain quiet in the coming time period.
NASA’s Solar Dynamics Observatory reveals the Sun’s activity
The team made their discovery using a newly created database of images of the Sun’s active regions taken by SDO, which combines more than eight years of images taken of active regions in ultraviolet and extreme ultraviolet light.
Karin Disauer, database project manager, commented: “This is the first time a database like this has been readily available to the scientific community and will be very useful for studying many topics, not just blaze-ready active regions. “
Two images of a solar active region (NOAA AR 2109) taken by SDO/AIA show extreme ultraviolet light produced by million-degree-hot coronal gas (top images) the day before the region flared up (left) and the day before it remained quiet and did not ignite (right). Luminance changes (bottom images) at these two times show different patterns, with patches of intense variation (black and white areas) before the flare (bottom left) and mostly gray (indicating low variability) before the quiet period (bottom right).
The NWRA examined a large sample of active regions from the database using statistical methods to identify small flashes in the corona before each solar flare. The discovery gives scientists a deeper understanding of the physics occurring in magnetically active regions, helps understand space weather, and could develop an advanced tool for predicting solar flares.
Dissauer concludes: “With this study, we really start to dig deeper. Later, combining all this information from the surface up through the corona should allow forecasters to make better predictions about when and where solar flares will occur.
The study “Properties of active regions with inevitable flaring versus quiescent active regions from the chromosphere through the corona. II. Nonparametric Discriminant Analysis Results from the NWRA Classification Infrastructure (NCI)’ is published in The Astrophysical Journal.
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