Detection of continuum emission and atomic hydrogen (HI) from comet C/2020 F3 NEOWISE using GMRT

Abstract: Comets are the most primordial objects in our solar system. Comets are icy bodies that release gas and dust when they move close to the Sun. The C/2020 F3 (NEOWISE) was a nearly isotropic comet that was moving in a near-parabolic orbit. The comet C/2020 F3 (NEOWISE) was the brightest comet in the northern hemisphere after comet Hale-Bopp in 1997 and comet McNaught in 2006. In this article, we reported the first interferometric high-resolution detection of the comet C/2020 F3 (NEOWISE) using the Giant Metrewave Radio Telescope (GMRT). We detected the radio continuum emission from comet C/2020 F3 (NEOWISE) with flux density level 2.84($\pm$0.56)$-$3.89($\pm$0.57) mJy in the frequency range 1050$-$1450 MHz. We also detected the absorption line of atomic HI with Signal to Noise Ratio (SNR) $\sim$5.7. The statistical column density of the detected HI absorption line was $N_{HI} = (3.46\pm0.60)\times(T_{s}/100)\times10^{21}$ cm$^{-2}$ where we assumed spin temperature $T_{s}$ = 100 K and filling factor $f$ = 1. The significant detection of continuum emission from the comet C/2020 F3 (NEOWISE) in $\sim$21 cm wavelength indicated that it arose from the large Icy Grains Halo (IGH) region.