Scientists analyzing data from India’s Aditya-L1 space observatory have identified key mechanisms explaining one of astrophysics’ most persistent puzzles: the extreme temperature differential between the Sun’s interior and its outer atmosphere.
The Sun’s core reaches approximately 15 million degrees Celsius, while its visible surface measures around 5,500 degrees. However, the corona—the outermost atmospheric layer—maintains temperatures of roughly 2 million degrees, occasionally spiking to 40 million degrees. This inverts conventional physics expectations, as temperatures should decrease with distance from the heat source. Research led by Prof R Ramesh of the Indian Institute of Astrophysics, published in the Astrophysical Journal Letters, addresses why this counterintuitive condition persists.
The corona regularly experiences violent disturbances including solar flares and coronal mass ejections (CMEs), during which enormous quantities of energy release into space. During low-activity periods, the Sun produces two to three CMEs daily, increasing to ten or more during peak solar cycles occurring every 11 years. These events trigger auroras and geomagnetic storms that can disrupt power infrastructure and satellite communications on Earth. The fundamental question concerns how the Sun replenishes its energy losses to maintain coronal temperatures.
Researchers identified two primary energy supply mechanisms. Convective motions on the Sun’s surface generate waves that transport energy outward, similar to ocean waves carrying debris toward shore. More significantly, the tangled magnetic field lines in the solar atmosphere constantly rupture and reconnect. During CMEs, these twisted field configurations rupture near sunspots and expel massive plasma clouds into space. Within hours, the magnetic field lines reconnect and restore energy to the corona.
Aditya-L1’s Visible Emission Line Coronagraph recorded a particularly energetic CME on 5 August 2024, enabling precise energy calculations. Analysis revealed that surface-generated waves supply approximately 7 percent of the corona’s energy requirement, while magnetic field reconfiguration provides the remaining 93 percent. This quantification provides a foundation for future investigations into solar atmospheric energy dynamics and fundamental physics principles governing stellar behavior.
Article Attribution | Read More at Article Source
Article summary produced by Claude AI