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Disintegration of Long-period Comet C/2019 Y4 (ATLAS). I. Hubble Space Telescope Observations

Ye, Quanzhi and Jewitt, David and Hui, Man-To and Zhang, Qicheng and Agarwal, Jessica and Kelley, Michael S. P. and Kim, Yoonyoung and Li, Jing and Lister, Tim and Mutchler, Max and Weaver, Harold A. (2021) Disintegration of Long-period Comet C/2019 Y4 (ATLAS). I. Hubble Space Telescope Observations. Astronomical Journal, 162 (2). Art. No. 70. ISSN 0004-6256. doi:10.3847/1538-3881/abfec3.

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The near-Sun comet C/2019 Y4 (ATLAS) is the first member of a long-period comet group observed to disintegrate well before perihelion. Here we present our investigation into this disintegration event using images obtained in a three-day Hubble Space Telescope campaign. We identify two fragment clusters produced by the initial disintegration event, corresponding to fragments C/2019 Y4-A and C/2019 Y4-B identified in ground-based data. These two clusters started with similar integrated brightness but exhibit different evolutionary behavior. C/2019 Y4-A was much shorter-lived compared to C/2019 Y4-B and showed signs of significant mass loss and changes in size distribution throughout the three-day campaign. The cause of the initial fragmentation is undetermined by the limited evidence but crudely compatible with either the spin-up disruption of the nucleus or runaway sublimation of subsurface supervolatile ices, either of which would lead to the release of a large amount of gas as inferred from the significant bluing of the comet observed shortly before its disintegration. Gas can only be produced by the sublimation of volatile ices, which must have survived at least one perihelion passage at a perihelion distance of q = 0.25 au. We speculate that Comet ATLAS is derived from the ice-rich interior of a nonuniform, kilometer-wide progenitor that split during its previous perihelion. This suggests that comets down to a few kilometers in diameter can still possess complex, nonuniform interiors that can protect ices against intense solar heating.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Ye, Quanzhi0000-0002-4838-7676
Hui, Man-To0000-0001-9067-7477
Zhang, Qicheng0000-0002-6702-191X
Agarwal, Jessica0000-0001-6608-1489
Kelley, Michael S. P.0000-0002-6702-7676
Kim, Yoonyoung0000-0002-4676-2196
Lister, Tim0000-0002-3818-7769
Mutchler, Max0000-0002-0088-3021
Weaver, Harold A.0000-0003-0951-7762
Additional Information:© 2021. The American Astronomical Society. Received 2021 March 1; revised 2021 May 4; accepted 2021 May 5; published 2021 July 21. We thank two anonymous referees for their review, as well as Matthew Knight for helpful discussion and comments. This research is based on observations made with the NASA/ESA Hubble Space Telescope obtained from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. Support for this work was provided by NASA through grant Nos. HST-GO-16089 and 16111 from the Space Telescope Science Institute. J.A. and Y.K. acknowledge funding by the Volkswagen Foundation. J.A.'s contribution was made in the context of ERC Starting Grant 757390 CAstRA. This research made use of Montage and Photutils. Montage is funded by the National Science Foundation under grant No. ACI-1440620 and was previously funded by the National Aeronautics and Space Administration's Earth Science Technology Office, Computation Technologies Project, under Cooperative Agreement Number NCC5-626 between NASA and the California Institute of Technology. Photutils is an Astropy affiliate package for the detection and photometry of astronomical sources. Facilities: HST(WFC3). Software: L.A. Cosmic (van Dokkum 2001), Montage (Jacob et al. 2010), Photutils (Bradley et al. 2020), SCAMP (Bertin 2010), TinyTim (Krist et al. 2011).
Funding AgencyGrant Number
NASANAS 5-26555
Volkswagen FoundationUNSPECIFIED
European Research Council (ERC)757390
Subject Keywords:Comet nuclei; Comet interiors; Comets; Long period comets
Issue or Number:2
Classification Code:Unified Astronomy Thesaurus concepts: Comet nuclei (2160); Comet interiors (272); Comets (280); Long period comets (933)
Record Number:CaltechAUTHORS:20210803-152826508
Persistent URL:
Official Citation:Quanzhi Ye et al 2021 AJ 162 70
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:110128
Deposited By: Tony Diaz
Deposited On:04 Aug 2021 18:33
Last Modified:04 Aug 2021 18:33

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