In a groundbreaking achievement, a team of solar physicists led by researchers from the National Centre for Radio Astrophysics (NCRA), Pune, has leveraged the MeerKAT radio telescope in South Africa to observe the Sun, producing remarkably detailed radio images. These images have unveiled previously unseen faint and minute features of the Sun’s atmosphere.
Dr. Devojyoti Kansabanik, spearheading the research alongside Dr. Surajit Mondal, both alumni of the National Centre for Radio Astrophysics, Tata Institute of Fundamental Research (NCRA-TIFR), Pune, conducted their doctoral research under the guidance of Professor Divya Oberoi from NCRA. Dr. Kansabanik has recently embarked on the NASA Jack Eddy postdoctoral fellowship at the Applied Physics Laboratory of Johns Hopkins University, USA, while Dr. Mondal is currently a postdoctoral fellow at the Centre for Solar Terrestrial Research of the New Jersey Institute of Technology, USA.
Despite the Sun’s prominence and centuries of scrutiny, it remains a complex entity to study, particularly at radio wavelengths. Dr. Kansabanik emphasized, “The Sun is, in fact, a surprisingly challenging source to study, especially at radio wavelengths.” Radio emissions stemming from the Sun’s tenuous atmosphere, known as the corona, present a puzzle, visible only during total eclipses and serving as the cradle for phenomena affecting Earth’s environment, known as space weather.
Dr. Mondal shed light on the intricacies of solar imaging, explaining the rapid temporal and spectral changes in emissions, akin to a fast-moving car blurring in photographs. Overcoming these challenges required a novel observation strategy wherein the telescope was directed slightly away from the Sun, akin to peripheral vision, enabling observation while introducing complexities in image fidelity.
To mitigate these effects, rigorous efforts were invested in understanding and correcting instrumental and observational aberrations. Dr. Kansabanik elaborated, “We put in a lot of effort into understanding the effects of the instrument and the peripheral vision due to unconventional observing mode. We developed algorithms to estimate and correct the effects of both the instrument and peripheral vision.”
Following meticulous corrections, the researchers successfully generated high-fidelity solar images, validated through comparisons with simulations. Professor Oberoi lauded the achievement, stating, “The high fidelity of the images we obtained in this study demonstrated that MeerKAT can provide unprecedentedly detailed solar images and will open a new frontier in solar physics.”
Situated in South Africa’s Karoo desert, MeerKAT, comprising 64 radio dishes with a diameter of 13.5 meters each, holds promise as a precursor to the mid-frequency telescope of the Square Kilometre Array Observatory (SKAO). While currently the optimal instrument for spectroscopic and snapshot solar imaging at GHz frequencies, astronomers face challenges in realizing high-fidelity spectroscopic solar images using MeerKAT.
