Solar eruptions found to reach temperatures six times hotter than previously thought

Wednesday 03 September 2025 - 15:50

By: Dakir Madiha

Solar eruptions found to reach temperatures six times hotter than previously thought

Scientists at the University of St Andrews have uncovered a groundbreaking phenomenon that challenges long-standing assumptions in solar physics. Their research, published in The Astrophysical Journal Letters, reveals that particles within solar eruptions can reach temperatures exceeding 60 million degrees Celsius, which is 6.5 times hotter than earlier estimates. This finding could resolve a decades-old mystery

A new perspective on solar heating

Led by Dr. Alexander Russell from the School of Mathematics and Statistics, the study overturns the traditional understanding that ions and electrons in solar eruptions exhibit similar temperatures. Instead, the research demonstrates that ions are heated significantly more intensely than electrons, driven by a process called magnetic reconnection.

Dr. Russell described this discovery as “a universal law,” validated through studies of the solar wind, near-Earth space phenomena, and computational modeling. He noted that no prior research had connected these insights directly to solar eruptions. The team’s analysis of modern data revealed that temperature disparities between ions and electrons persist far longer than previously believed, lasting for several minutes in critical regions of solar eruptions. This contradicts the earlier assumption that these particles quickly equilibrate in temperature.

Solving the spectral line mystery

Since the 1970s, astrophysicists have been puzzled by the unexpectedly broad spectral lines observed during solar eruptions. These bright emissions in ultraviolet and X-ray wavelengths were attributed to turbulence in the Sun’s atmosphere, but the exact nature of this turbulence remained elusive.

The St Andrews research offers a fresh explanation: the extreme temperatures of ions within eruptions could account for much of the spectral broadening, reducing the role previously assigned to turbulence. This paradigm shift aligns better with observed data and provides a revised framework for understanding the dynamics of solar eruptions.

Implications for space weather and technology

The study’s findings hold significant practical value as reliance on space-based infrastructure increases. Solar eruptions produce intense bursts of X-rays and radiation that can disrupt communication systems, damage spacecraft electronics, and pose health risks for astronauts.

Recognizing that ions in these eruptions are far hotter than expected could influence the design of spacecraft shielding, improve radiation risk assessments, and enhance the accuracy of space weather forecasts. These insights are particularly timely during the current solar cycle, which has seen a surge in extreme solar activity.

This breakthrough marks a pivotal moment in solar physics, laying the groundwork for further exploration of how the Sun’s explosive energy releases impact Earth’s technological systems and future space missions.