A new study from the University of St Andrews has shed light on one of the longest-standing mysteries in astrophysics.
The research, published in Astrophysical Journal Letters, reveals that particles within solar flares can reach temperatures over six times hotter than previously thought.
This unexpected finding could transform our understanding of how the Sun behaves and its impact on Earth.
The research, led by Dr Alexander Russell from the School of Mathematics and Statistics, demonstrates that ions – the positively charged particles that make up half of solar plasma – can heat to an astonishing 60 million degrees.
For decades, scientists assumed that ions and electrons within flares shared the same temperature, but the latest calculations challenge this long-held belief.
What are solar flares?
Solar flares are sudden, colossal bursts of energy in the Sun’s outer atmosphere. They occur when magnetic energy, stored in the solar corona, is suddenly released.
These events are not only spectacular but also significant for life on Earth. Solar flares dramatically increase the Sun’s X-ray and ultraviolet radiation output.
When this energy reaches Earth, it can disrupt communication systems, interfere with GPS signals, damage spacecraft electronics, and pose risks to astronauts.
They also cause changes in our planet’s upper atmosphere, sometimes leading to intensified auroras.
In essence, while solar flares are a natural part of the Sun’s activity cycle, they highlight the delicate connection between space weather and daily life on Earth.
Solving a 50-year-old mystery
The new research may finally resolve a puzzle that has confounded solar physicists since the 1970s.
For decades, scientists struggled to explain why solar flare spectral lines – bright signals at specific wavelengths of ultraviolet and X-ray light – appear broader than theoretical models predicted.
Previously, this discrepancy was blamed on turbulence within the solar atmosphere. However, identifying the exact nature of that turbulence proved elusive.
The St Andrews study offers a groundbreaking alternative: the excess width of the spectral lines may not be turbulence at all, but rather the extreme heat of ions within the flares.
By showing that ions can be heated 6.5 times more strongly than electrons through a process called magnetic reconnection, the team has provided a new framework for interpreting solar flare data.
This paradigm shift aligns better with observational evidence and computer simulations, suggesting scientists may need to reconsider how they model solar events altogether.
Future implications
Understanding solar flares is not just about solving academic mysteries – it has real-world consequences.
As humanity becomes more reliant on satellites and long-duration space missions, predicting and mitigating the effects of solar storms is critical.
If ions within solar flares are far hotter than expected, this could influence how we design spacecraft shielding, assess radiation hazards for astronauts, and forecast space weather more accurately.
The study underscores how interconnected the cosmos is with life on Earth. By unlocking the secrets of solar flares, scientists are not only deepening our knowledge of the Sun but also protecting the technologies and explorers that reach beyond our planet.