New Delhi, Jul 16: Astronomers at the Indian Institute of Astrophysics (IIA), an autonomous institute under the Department of Science and Technology (DST), have decoded the series of powerful solar eruptions resulting in rare northern lights dancing across Ladakh's night skies in May 2024.

The solar eruptions, called Coronal Mass Ejections (CMEs), are massive ejections of magnetised plasma from the Sun’s corona. The CMEs can cause geomagnetic storms capable of disrupting satellite operations, communication systems, and power grids.

The IIA team showed that the great geomagnetic storm that started on 10th May 2024 was linked to a rare sequence of six different CMEs erupting in succession, 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 understand, a team of solar astrophysicists at IIA built a model using observations from the NASA and ESA space missions.

They investigated the way the rare chain of six interacting solar blasts reported from IIA’s Indian Astronomical Observatory in Hanle, Ladakh, interacted with each other and evolved thermally en route from the Sun to Earth, resulting in IIA’s.

The team traced not just the paths but the temperatures and magnetic states of these blasts as they expanded across the solar system.

“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 lead author Soumyaranjan Khuntia, a doctoral scholar at IIA.

The study revealed that most CMEs initially released heat but later transitioned into a state that gets heated instead, particularly to a near-constant temperature state as they expanded further from the Sun.

The team found that these solar clouds do not just carry heat but change their thermal behaviour mid-journey. Initially, the CMEs release heat but then enter a state where they actually absorb and hold onto it.

“This 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. Wageesh Mishra, a faculty member at IIA.

The findings, published in the Astronomy and Astrophysics Journal, offers a major step forward for improving space weather forecasting models, particularly in predicting the impact of complex CME events on Earth's magnetosphere.

(IANS)

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