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

Comets are the most primordial objects in our solar system. Comets are icy bodies that release gas and dust when moving close to the Sun. The C/2020 F3 (Near-Earth Object Wide-field Infrared Survey Explorer: NEOWISE) is a nearly isotropic comet moving near-parabolic orbit. The C/2020 F3 (NEOWISE) was the brightest comet in the northern hemisphere after comet Hale–Bopp in 1997 and comet McNaught in 2006. This paper presents 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 the comet C/2020 F3 (NEOWISE) with a flux density level 2.84 (±0.56)–3.89 (±0.57) mJy in the frequency range of 1050–1450 MHz. We also detected the absorption line of atomic hydrogen (HI) with a signal-to-noise ratio (SNR) \(\sim \)5.7. The column density of the detected HI absorption line is \(N_{\textrm{HI}} = (3.46\pm 0.60)\times (T_{s}/100)\times 10^{21}\,\hbox {cm}^{-2}\), where we assume the spin temperature \(T_{s} = 100\) K and filling factor \(f = 1\). The significant detection of continuum emission from the comet C/2020 F3 (NEOWISE) at \(\sim \)21 cm wavelength indicated that it arose from the large icy grains halo (IGH) region.