A high-spectral-resolution catalog of emission lines in the visible spectrum of comet C/2020 F3 (NEOWISE)^⋆

¹ INAF Astronomical Observatory of Padova, Vicolo dell’Osservatorio 5, 35122 Padova, Italy
e-mail: pamela.cambianica@inaf.it
² Department of Physics and Astronomy “Galileo Galilei”, University of Padova, Vicolo dell’Osservatorio 3, 35141 Padova, Italy
³ INAF-IAPS, Via Fosso del Cavaliere 100, Tor Vergata, 00133 Roma, Italy
⁴ INAF Astronomical Observatory of Trieste, Via Tiepolo 11, 38121 Trieste, Italy
⁵ Fundación Galileo Galilei-INAF, Rambla José Ana Fernandez Pérez 7, 38712 Breña Baja, TF, Spain
⁶ Instituto de Astrofisica de Canarias, C/Via Lactea s/n, 38205 La Laguna, Tenerife, Spain
⁷ Departamento de Astrofisica, Univ. de La Laguna, Av. del Astrofisico Francisco Sánchez s/n, 38205 La Laguna, Tenerife, Spain

Received: 11 January 2021
Accepted: 29 September 2021

Abstract

Aims. Comet C/2020 F3 (NEOWISE) is considered to be the brightest comet observed in the northern hemisphere since the passage of comet C/1995 O1 (Hale-Bopp) in 1997. Since the study of comets offers a unique opportunity to investigate the early stages of the formation and evolution of our Sun and the Solar System, we obtained high-resolution optical spectra (R = λ/Δλ = 11 5000) of comet NEOWISE. The unique passage and its brightness yielded spectra with a large number of emission lines, providing information on the coma composition and the physical and chemical processes occurring in the nucleus. The spectra have been used to generate a catalog of emission lines to be used for future studies of comets since there are no catalogs in the literature with such a high spectral resolution.

Methods. Two high-resolution spectra of comet NEOWISE were obtained, on 26 July 2020 (geocentric distance of 0.7 AU) and 5 August 2020 (geocentric distance of 0.89 AU), with the High Accuracy Radial velocity Planet Searcher for the Northern hemisphere (HARPS-N) echelle spectrograph installed on the 360 cm Telescopio Nazionale Galileo. The spectra cover the range between 383 and 693 nm, and have been extracted using the HARPS-N Data Reduction Pipeline. To analyze the spectra and compile the high-resolution catalog, we collected several laboratory molecular line lists that cover the same wavelength range as that of our spectra. To validate the final identification, we compared our catalog with other atlases that resulted from the spectral analysis of other comets.

Results. We generate a high-spectral-resolution catalog of emission lines observed in comet NEOWISE, providing the identification for 4488 lines. We found cometary lines due to CN, CH, C₂, C₃, and NH₂ and atomic lines due to NaI and [OI].