Enlargement of depressions on comet 81P/Wild 2: Constraint based on 30-year cometary activity in the inner Solar System

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Hauptverfasser: Lim, Bumhoo, Ishiguro, Masateru
Format: Preprint
Veröffentlicht: 2024
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author Lim, Bumhoo
Ishiguro, Masateru
author_facet Lim, Bumhoo
Ishiguro, Masateru
contents Context. The Stardust flyby mission to Jupiter-family comet (JFC) 81P/Wild 2 (hereafter, 81P) captured its dense quasicircular depressions. Nevertheless, the formation mechanism remains a subject of ongoing debate. Aims. We aimed to study how cometary activity contributed to the formation and enlargement of these depressions by analyzing Stardust flyby images and ground-based observation data. Methods. We calculated the time-dependent water production rate of 81P inside the snow line (<3 au) and compared it with the observational data. In addition, we estimated the fallback debris mass using an observation-based model, where a dust ejection from 81P was considered to reproduce ground-based observations of the dust tail. We compared the total excavated volume of water and dust with the total depression volume derived using the 81P shape model. Results. We find that the total excavated volume after 81P was injected into the inner Solar System accounts for up to only 30 % of the depression volume. This insufficiency suggests that a large portion (>70 %) of the depressions had already existed before the comet was injected into the current orbit. In addition, we estimate the dust-to-ice mass ratio for 81P to be 2-14. Conclusions. We suggest that most depressions were formed in the source region of the Kuiper-belt objects.
format Preprint
id arxiv_https___arxiv_org_abs_2412_11548
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Enlargement of depressions on comet 81P/Wild 2: Constraint based on 30-year cometary activity in the inner Solar System
Lim, Bumhoo
Ishiguro, Masateru
Earth and Planetary Astrophysics
Context. The Stardust flyby mission to Jupiter-family comet (JFC) 81P/Wild 2 (hereafter, 81P) captured its dense quasicircular depressions. Nevertheless, the formation mechanism remains a subject of ongoing debate. Aims. We aimed to study how cometary activity contributed to the formation and enlargement of these depressions by analyzing Stardust flyby images and ground-based observation data. Methods. We calculated the time-dependent water production rate of 81P inside the snow line (<3 au) and compared it with the observational data. In addition, we estimated the fallback debris mass using an observation-based model, where a dust ejection from 81P was considered to reproduce ground-based observations of the dust tail. We compared the total excavated volume of water and dust with the total depression volume derived using the 81P shape model. Results. We find that the total excavated volume after 81P was injected into the inner Solar System accounts for up to only 30 % of the depression volume. This insufficiency suggests that a large portion (>70 %) of the depressions had already existed before the comet was injected into the current orbit. In addition, we estimate the dust-to-ice mass ratio for 81P to be 2-14. Conclusions. We suggest that most depressions were formed in the source region of the Kuiper-belt objects.
title Enlargement of depressions on comet 81P/Wild 2: Constraint based on 30-year cometary activity in the inner Solar System
topic Earth and Planetary Astrophysics
url https://arxiv.org/abs/2412.11548