A group of scientists working at the Pune-based National Centre for Radio Astrophysics (NCRA) have recently discovered tiny flashes of radio light emanating from all over the Sun, which they say could help in explaining the long-pending coronal heating problem.

“These radio lights or signals result from beams of electrons accelerated in the aftermath of a magnetic explosion on the Sun. While we have not seen the magnetic explosions, these weak radio flashes that we have discovered are ‘smoking guns’ or the evidence for the same and hence bring us closer to explaining the coronal heating problem,” said Professor Divya Oberai, faculty member at the NCRA.

Professor Oberoi said that these observations were the strongest evidence till date that the tiny magnetic explosions, originally referred to as ‘nanoflares’ by eminent American solar astrophysicist Eugene Parker, can indeed be heating up the corona (the aura of plasma that surrounds the sun and other stars).

He said that while the phenomenon of coronal heating has been known for the last 70 years, the availability of cutting edge data from the Murchison Widefield Array (MWA) radio telescope proved to be a game-changer.

“With this work, we have the strongest evidence till date of these magnetic explosions or ‘nanoflares’ as called by Prof. Parker in a theory he put forth in 1988. Our discoveries were greatly facilitated by availability of data from the MWA and our work at the NCRA,” Prof. Oberoi said.

The research on this was carried out by Surajit Mondal, a Ph.D. student at NCRA working under the Prof. Oberoi’s supervision, along with Dr. Atul Mohan, a former student of his at the NCRA, who is presently based at the Rosseland Centre for Solar Physics in Norway.

“The strength of the magnetic fields varies a lot from one place on the surface of the Sun to another, by more than a factor of 1,000. But the corona is hot everywhere. So, this heating process has to work all over the corona, even in regions of weak magnetic fields. Until now, the process of how this magnetic energy is deposited in the corona had remained a mystery. Now, our observations can bring us closer to solving this,” he said.

The three scientists have jointly written a paper on their discoveries titled ‘First Radio Evidence for Impulsive Heating Contribution to the Quiet Solar Corona’, which was published on Tuesday in Astrophysical Journal Letters.