Photometry and Long-Slit Spectroscopy of Split Comet C/2019 Y4 (ATLAS)

TL;DR

This study presents photometric and spectroscopic analysis of split comet C/2019 Y4 (ATLAS), revealing molecular emissions, fragment detection, and temporal variations, contributing to understanding its composition and dynamical history.

Contribution

It provides detailed spectroscopic data and dynamical analysis of comet C/2019 Y4 (ATLAS), including molecular emissions, fragment identification, and orbit comparison, which are novel insights.

Findings

Detected CN, C2, C3, NH2 emissions in the comet.

Identified four fragments in the coma.

Concluded the comet likely does not share a common progenitor with C/1844 Y1.

Abstract

We present an analysis of the photometric and spectroscopic observations of the split comet C/2019 Y4 (ATLAS). Observations were carried out on the 14th and 16th of April 2020 when the heliocentric distances of the comet were 1.212 and 1.174 au, its geocentric distances 0.998 and 0.991 au, and the phase angle 52.9{\deg} and 54.5{\deg}, respectively. The comet was observed with the 6-m BTA telescope of the Special Astrophysical Observatory (Russia) with the SCORPIO-2 multi-mode focal reducer. The narrow-band BC and RC cometary filters in the continuum were used. We identified numerous emissions of the CN, C2, C3, and NH2 molecules within the range of 3750-7100 {\AA}. The C2/CN and C3/CN production rate ratios coincide with those of typical comets. Four fragments belonging to the coma were detected in both observational runs. We compared and analyzed temporal variations of the visual magnitudes, gas productivity, and dust colour. Based on our dynamical investigation of the orbits of comets C/1844 Y1 (Great comet) and C/2019 Y4 (ATLAS), we can claim that, with high probability, two comets do not have a common progenitor.