While it is widely known that the main phase of a solar flare, a sudden event on the Sun that releases a burst of energy,  can cause disruption to GPS signals and trigger radio blackouts across the globe, this research explores the less studied secondary emission known as the EUV (Extreme Ultraviolet) late phase.

Published today in The Astrophysical Journal, the findings suggest that this late phase might be equally as disruptive to communication and satellite systems, raising concerns about the broader implications of solar activity on our technology-dependent world.

In addition, the energy in the late phase can potentially exceed that of the main phase due to its longer duration, leading to a more prolonged impact on the ionosphere.

Corresponding author, Dr Susanna Bekker from the School of Mathematics and Physics at Queen’s commented on the findings: “The study of the influence of solar flares on the Earth’s upper atmosphere, known as the ionosphere, remains to be a significant focus. Studies have indicated that the illuminated part of the Earth’s ionosphere is extremely sensitive to variations in solar radiation fluxes, which can cause failures in technology that people rely on daily.”

The first recording of the impact of solar flares on the Earth’s ionosphere dates to over a century ago. The main phase of a solar flare has been studied at length, however recent findings have shown that a large fraction of flares have an EUV late phase, whose influence is not yet as clear.

Solar flares are classed in relation to how powerful they are and the potential impact they could have on Earth, with an X flare deemed the most aggressive.

The researchers from the School of Mathematics and Physics at Queen’s delved into the data from previous X-class flares to analyse synchronous variations in solar radiation and ionospheric electron density in response to an EUV late phase flare.

Dr Bekker explained: “Analysing the example of the X2.9 class flare, it showed that the total electron content (TEC) response to the late phase is almost 30% of the response to the main phase.

“During more powerful events, the effect on the ionosphere is much higher, therefore the late phase can also have a negative impact on the accuracy of navigation systems and the stability of radio communications.”

Dr Ryan Milligan, School of Mathematics and Physics is co-author of the paper, he added: “These findings mark a new direction of research that is taking place at the Astrophysics Research Centre at Queen’s. We have been involved in the study of solar flares for many years, but we are currently developing a new research direction that will focus on space weather effects, such as solar flares, and their impact on Earth.

“The insights gained from this research may also be applicable to the study of planets around other stars. We believe that further study of the complex dynamics of ionospheric layers due to changes in the Sun’s behaviour is necessary to improve the accuracy of modelling and forecasting such events.”

The paper can be read in full here.

Dr Susanna Bekker

School of Mathematics and Physics

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