New findings from India's Aditya-L1 space observatory have shed light on one of astrophysics' enduring puzzles: why the Sun's outer atmosphere is millions of degrees hotter than its surface. Research led by Indian scientists quantifies the energy sources maintaining this extreme temperature.
One of the most perplexing questions in solar physics has long been why the Sun's corona—its outermost atmospheric layer—maintains temperatures of approximately 2 million degrees Celsius, far exceeding the 5,500-degree surface below it. This contradiction defies conventional physics understanding. According to research published in the Astrophysical Journal Letters, India's Aditya-L1 solar observation mission has now provided crucial evidence addressing this paradox.
Led by Prof R Ramesh of the Indian Institute of Astrophysics, the study examined a particularly energetic coronal mass ejection (CME) that occurred on August 5, 2024. CMEs are explosive events where the Sun releases massive amounts of energy into space, potentially affecting Earth's power grids and communication systems. Scientists have long questioned how the Sun replenishes its energy after such significant losses.
The research identifies two primary mechanisms responsible for maintaining the corona's temperature. The first involves surface vibrations generating waves that transport energy outward, similar to ocean waves carrying foam. The second mechanism involves magnetic field lines in the Sun's atmosphere that snap and reconnect, releasing energy in the process. According to Prof Ramesh's findings, the magnetic reconnection process supplies approximately 93 percent of the energy needed to maintain the corona's extreme temperature, while surface-generated waves contribute only 7 percent.
The study observed that following the August 2024 CME, tangled magnetic field lines returned to their original configuration within ten hours, effectively restoring the corona's energy. Prof Ramesh suggests these findings provide critical benchmarks for future solar research and may help answer fundamental physics questions about stellar atmospheres.
