Photometric and numerical study of comet C/2021 A1 (Leonard) near its estimated disruption date

Abstract

Initially on an elliptical orbit, C/2021 A1 experimented significant changes in its orbital configuration due to planetary perturbations upon entering the planetary region. Images of the comet C/2021 A1 (Leonard) obtained in March 2022 allow to estimate that its disintegration occurred in December 2021. The aim of this paper is to analyze the comet’s dust behavior during the period when its disintegration is presumed to have commenced, so a series of images of this comet on the broadband B, V, and R filters were taken on December 21 and 23, 2021 with the 0.6 m Helen Sawyer Hogg (HSH) telescope at the Complejo Astron´omico El Leoncito (CASLEO) to do a morphological, photometric, and numerical analysis of this comet. Analysis of the magnitudes and dust production rate suggests a significant increase in activity on December 21 compared to two days later, indicating a potential outburst. Digital filters were applied to enhance contrast in the cometary images, revealing two active regions on opposite sides of the nucleus. Additionally, the A(0◦) f ρ parameter was obtained for this comet. Finally, to gain deeper insights into Leonard’s dust behavior,observations were fitted to a newly developed theoretical model for studying dust comas. Combined with photometric data and gas production information from the literature, the analysis suggests that the comet’s activity on December 21, 2021, may mark the beginning of its disintegration.