An international team of scientists, including two astrophysicists from Bengaluru, shed new light on the 142-year-old solar mystery on Friday and in the process opened a fresh window to look at one of the sun's biggest enigmas.
A team of researchers from the Indian Institute of Astrophysics discovered how solar specks – small-scale plasma planes, of which millions are present in the sun at any given moment – are born and die on the verge.
The discovery could help uncover one of the biggest mysteries yet to be solved in astrophysics – as temperatures rise in the solar corona.
Corona is the outer atmosphere of the Sun, which extends outward for several million kilometers above the sun's surface. Although the temperature at the core of the Sun is close to 15 million degrees Celsius, it drops to only 5,700 degrees on the sun's surface (the photosphere).
However, above the photosphere, the temperature begins to rise again with height reaching one million degrees or more in the corona. What causes such a rise in corona temperature despite being away from the core remains a mystery.
Tanmoy Samantha, who earned a PhD at IIA, his superior and IIA scientist, Dipankar Banerjee, and their colleagues from China, the US and Europe, believe that solar speckles give them a chance to break the riddle.
Discovered by Father Secchi in 1877, the solar specks are massive (3000-5000 km long and 200-500 km wide) magnetized plasma-like jet planes, found everywhere in the chromosphere, the interface between the photosphere and the corona.
"Studying them is difficult because each bracket – from formation to collapse – only takes a few minutes, but there are about a million of them in the sun at any given moment," Samantha told DC.
Old-generation solar telescopes were not sophisticated enough to study such features. The breakthrough came as the team made inroads with the 1.6-meter Goude solar telescope at the Big Bear Solar Observatory, California, the world's largest solar telescope.
Not only did the telescope deliver huge detail with great detail, but it measured the magnetic fields in the high spatial resolution photosphere.
"The speckles were created from two magnetic fields of opposite polarity, destroying each other, generating kinetic and thermal energy. This leads to the creation of plasma planes, which in turn may contribute to the increased corona temperature. But we need to study more to be sure, "Samantha explained. The findings are published in the journal Science on Friday.
Scientists now had to perform advanced computer simulations and theoretical tests based on these new exciting results to solve the longstanding problem of coronary heating.