IIA team decodes reason behind May 2024 solar eruptions

Bengaluru

Astronomers at the Indian Institute of Astrophysics (IIA) have decoded the reasons behind the series of powerful solar eruptions or Coronal Mass Ejections (CMEs) that resulted in rare northern lights dancing across the Ladakh’s night skies in May 2024.

These findings offer a major step forward in the improvement of space weather forecasting models, particularly in predicting the impact of complex CME events on Earth’s magnetosphere.

CMEs are massive ejections of magnetised plasma from the Sun’s corona. When such solar blasts are directed toward the Earth, they can cause geomagnetic storms capable of disrupting satellite operations, communication systems, and power grids.

According to the Department of Science and Technology, the great geomagnetic storm that started on 10 May, 2024, was linked to a rare sequence of six different CMEs erupting in succession, and it was associated with both solar flares and filament eruptions from an interacting complex active region on the Sun.

Until now, gaining a complete understanding of how CMEs evolve thermodynamically as they travel from the Sun to Earth has remained challenging, primarily due to limited observations near the Sun as well as in near-Earth space.

To bridge this gap, a team of solar astrophysicists led by Wageesh Mishra, a faculty member at IIA, used observations from the NASA and ESA space missions.

They built a model to investigate the manner in which the rare chain of six interacting solar blasts reported from IIA’s Indian Astronomical Observatory at Hanle in Ladakh interacted with each other and evolved thermally en route from the Sun to Earth.

“The study is the first of its kind, both in India and internationally, to capture the continuous thermodynamic evolution of multiple interacting CMEs across such a vast distance in the heliosphere,” said Dr. Mishra.

“Our analysis demonstrates that CME-CME interactions lead to significant thermal restructuring within. By the time they reach the Earth, the electrons in the complex ejecta were found to be in the heat-releasing state, while ions displayed a mix of heating and cooling behaviour, with the heating state being the dominant mode overall,” said Soumyaranjan Khuntia, the lead author and a doctoral scholar at IIA.