Astrophysicists in India have taken big steps in cracking one of Sun's mysteries: why its outer atmosphere,the corona, gets so much hotter than its surface. India's first solar mission, Aditya-L1, is shedding light on how the corona stays scorching despite energy loss during solar eruptions.
Published in Astrophysical Journal Letters,research by Prof. R. Ramesh from Indian Institute of Astrophysics shows temperature differences in Sun's layers challenge known physical laws . Sun's core hits about 15 million degrees Celsius, surface around 5,500 degrees. But corona can get up to 2 million degrees, sometimes 40 million.
Prof. Ramesh says corona is birthplace of major solar events like solar flares and CMEs, which shoot vast energy into space. These can create stunning auroras on Earth but also trigger geomagnetic storms disrupting power grids, satellite communications. Sun spews out two to three CMEs daily in low activity, over ten during peak solar cycles,roughly every 11 years .
Even with big energy loss during these eruptions, Sun hasn't weakened . Prof . Ramesh points out this means there's a way corona's energy gets refilled. Study identifies two main factors. First,bubbling on Sun's surface sends energy waves out,like ocean waves carrying foam. Second, Sun's tangled magnetic field lines play key role. These lines, like braided hair, snap and reconnect, moving energy.
CMEs happen when these twisted lines break,sending clouds of magnetized plasma into space. They often start near sunspots, cooler areas with strong magnetic fields. But magnetic lines reconnect fast,helping Sun recover lost energy in hours.
The team measured energy from both surface bubbling and magnetic field shifts. They found surface waves add little,just 7% of energy needed to keep corona hot. The rest, 93%, comes from Sun's magnetic field reconfigurations after CMEs.
To reach these conclusions,they studied a powerful CME from August 5, 2024. Using Aditya-L1's coronagraph,Velc,they saw magnetic lines snapped back to shape within ten hours,restoring corona's energy .
Prof. Ramesh sees surface bubbling's role but stresses magnetic fields' dominance in corona's temperature. He thinks this sets a new standard for future sun studies.
These findings could answer long-standing physics questions. Understanding Sun's actions is crucial for predicting space weather impacts on Earth .
As India pushes its space exploration, Aditya-L1's findings mark a big leap in solar research, promising more secrets from our closest star.
