Comets and Asteroids

Dust And Volatiles In The Disintegrating Comet C/2019 Y4 (ATLAS)

By Keith Cowing
Status Report
January 5, 2024
Filed under , , , , ,
Dust And Volatiles In The Disintegrating Comet C/2019 Y4 (ATLAS)
Slit views of C/2019 Y4 (ATLAS) on 2020 April 13.53 and 20.53 (UT). The ephemeris positions of the two major fragments A and B (from MPEC 2020-L06 and 2023-J29, respectively) are marked. On April 13.53 (UT), the slit was centered on A. On April 20.53 (UT), the slit was over both A and B. The rectangles, 4.1′′ in height and 2.3′′ in width, along the slits are sub-apertures. They were used to extract sub-aperture spectra (see §3). The arrows in the upper right corner mark the north and the east directions, and those in the lower right corners mark the velocity and comet-Sun vectors — astro-ph.EP

C/2019 Y4 (ATLAS) is an Oort cloud comet with an orbital period of ∼5895yr. 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 3600–8700A˚ 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, C2, C3, and NH2 which are superimposed on a dust scattering continuum, typical of cometary spectra in the optical.

The production rates of CN, C2, and C3 derived using the Haser model and the corresponding C2/CN and C3/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 Afρ quantities.

Its dust-scattering reflectivity is slightly red, with a gradient of ∼5% per 103A˚. We model the reflectivity gradient in terms of porous dust and find that the red color is accounted for by porous dust.

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

Comments: 18 pages, 8 figures, 4 tables, accepted for publication in ApJ
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2401.02073 [astro-ph.EP] (or arXiv:2401.02073v1 [astro-ph.EP] for this version)
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Submission history
From: Ruining Zhao
[v1] Thu, 4 Jan 2024 05:47:47 UTC (1,513 KB)
Astrobiology, Astrochemistry,

Explorers Club Fellow, ex-NASA Space Station Payload manager/space biologist, Away Teams, Journalist, Lapsed climber, Synaesthete, Na’Vi-Jedi-Freman-Buddhist-mix, ASL, Devon Island and Everest Base Camp veteran, (he/him) 🖖🏻