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arXiv · 2401.02073

Dust and Volatiles in the Disintegrating Comet C/2019 Y4 (ATLAS)

Ruining Zhao·Aigen Li·Bin Yang·Liang Wang·Huijuan Wang·Yu-Juan Liu·Jifeng Liu
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Abstract

C/2019 Y4 (ATLAS) is an Oort cloud comet with an orbital period of $\sim$5895$\,{\rm yr}$. Starting in March 2020, its nucleus underwent disintegration. In order to investigate the gas and dust properties of C/2019 Y4 (ATLAS) during its disintegration, we obtained long-slit spectra at 3600--8700$\,{\rm\mathring{A}}$ and $BVRI$ multi-band images with the Xinglong 2.16-Meter Telescope in April 2020. Our observations revealed that C/2019 Y4 (ATLAS) exhibited strong emission bands of CN, C$_2$, C$_3$, and NH$_2$ which are superimposed on a dust scattering continuum, typical of cometary spectra in the optical. The production rates of CN, C$_2$, and C$_3$ derived using the Haser model and the corresponding C$_2$/CN and C$_3$/CN ratios suggest that C/2019 Y4 (ATLAS) is a ``typical'' Oort cloud comet under the A'Hearn classification, although it appears less dusty as revealed by the $Af\rho$ quantities. Its dust-scattering reflectivity is slightly red, with a gradient of $\sim$5% per $10^3\,{\rm\mathring{A}}$. We model the reflectivity gradient in terms of porous dust and find that the red color is accounted for by porous dust.

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Ruining Zhao, Aigen Li, Bin Yang, Liang Wang, Huijuan Wang, Yu-Juan Liu, Jifeng Liu. 2024-01-04. Dust and Volatiles in the Disintegrating Comet C/2019 Y4 (ATLAS). https://doi.org/10.3847/1538-4357/ad1ab7

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