IIT-BHU physicist part of team making important discovery about sun
VARANASI: Using the world’s largest, 1.6 m Goode solar telescope, at the Big Bear Solar Observatory, Prof Ding Yuan and science team members, detected numerous dark features in a big sunspot, which appear as the coldest structure of the sun.
The globally acclaimed solar and heliospheric physicist in Indian Institute of TechnologyBanaras Hindu University, Dr Abhishek Kumar Srivastava was part of this investigation and played a significant role in framing the scientific works.
These dark features are plasma fibrils aligned with a strong magnetic field at kiloGauss at the sunspot. The fibrils oscillate transversely, which means this is a kink MHD wave and they are able to drag the kilo-Gauss magnetic field lines to move laterally. It implies that the fibril kink oscillations could potentially provide a very strong energy flux.
The team has developed a mathematical model of fast kink waves in sunspots and estimated that the energy flux is 1000 to 10000 times stronger than energy losses in active region plasma. This is sufficient to maintain the atmosphere of the Sun at a million-degree Kelvin temperature, according to a communique from IIT-BHU.
These novel scientific results, accompanied by the first ever high-resolution view of sunspot umbra, and high energy wave dynamics in its plasma fibrils were published in the prestigious Nature Astronomy Journal on May 25, the communique adds.
Dr Abhishek said that this new scientific discovery would change the view of strongly magnetized plasma regions of the Sun as it was never seen before and play a significant role in solving the most outstanding coronal heating problem. It would also be an outstanding scientific result for the next generation solar telescopes and a ready reference to the laboratory plasma experiments in which scientists were trying to confine the plasma and generate green energy for the benefit of mankind.
He further informed that the sun was powered by nuclear fusion of hydrogen at the core, where the temperature reached 16,000,000 degrees Celsius. At the visible surface (or photosphere) of the sun the temperature dropped to about 5,800 degrees Celsius. It was intuitive that the hydrogen gas located further away from its core should be cooler. The corona was more distant from the core than the photosphere, but its temperature reached millions of degrees. No current theory could explain this counter-example. This was called the coronal heating problem, a century-long challenge to physicists, he said.