India's Aditya-L1 Finds Magnetic Reconnection Supplies 93% of the Sun's Corona Energy

Astrophysicists using India's Aditya-L1 solar observatory have quantified for the first time how the Sun's corona stays at millions of degrees Celsius — and found that snapping and reconnecting magnetic field lines supply about 93 percent of the required energy, BBC News reported on August 14. The study, led by Professor R. Ramesh of the Indian Institute of Astrophysics and published in the Astrophysical Journal Letters, examined a powerful coronal mass ejection recorded on August 5, 2024, by Aditya-L1's Visible Emission Line Coronagraph.

A 90-Year-Old Puzzle, Quantified

The Sun's visible surface is about 5,500 degrees Celsius, yet its outer atmosphere — the corona, source of solar flares and CMEs — reaches about 2 million degrees and can spike to 40 million. Two mechanisms have long been debated: waves generated by boiling motions on the solar surface, and the constant snapping and reconnecting of tangled magnetic field lines. Ramesh's team found the waves contribute only about 7 percent of the energy, with the remaining 93 percent coming from magnetic reconfiguration. "The magnetic field lines snapping and reconnecting everywhere on the Sun are the primary source," Ramesh said, noting the findings provide an important benchmark for future research into the Sun's atmosphere.