Issue |
A&A
Volume 690, October 2024
|
|
---|---|---|
Article Number | A193 | |
Number of page(s) | 12 | |
Section | Planets and planetary systems | |
DOI | https://doi.org/10.1051/0004-6361/202451225 | |
Published online | 08 October 2024 |
New evidence supporting past dust ejections from active asteroid (4015) Wilson–Harrington
1
Department of Physics and Astronomy, Seoul National University,
1 Gwanak-ro,
Gwanak-gu, Seoul
08826,
Republic of Korea
e-mail: jsh854@snu.ac.kr
2
SNU Astronomy Research Center, Department of Physics and Astronomy, Seoul National University,
1 Gwanak-ro,
Gwanak-gu, Seoul
08826,
Republic of Korea
3
Nayoro Observatory,
157-1 Nisshin,
Nayoro, Hokkaido,
096-0066,
Japan
4
Center for Astronomy, University of Hyogo,
407-2 Nishigaichi,
Sayo, Hyogo
679-5313,
Japan
5
Astronomical Research Center, Chiba Institute of Technology,
2-17-1 Tsudanuma,
Narashino, Chiba
275-0016,
Japan
6
Planetary Exploration Research Center, Chiba Institute of Technology,
2-17-1 Tsudanuma,
Narashino, Chiba
275-0016,
Japan
7
Hiroshima Astrophysical Science Center, Hiroshima University,
1-3-1 Kagamiyama,
Higashi-Hiroshima, Hiroshima
739-8526,
Japan
8
Bisei Spaceguard Center, Japan Spaceguard Association,
1716-3 Okura, Bisei-cho,
Ibara, Okayama
714-1411,
Japan
9
Department of Earth and Planetary Sciences, Faculty of Science, Hokkaido University, Kita-ku,
Sapporo, Hokkaido
060-0810,
Japan
10
Department of Cosmosciences, Graduate School of Science, Hokkaido University, Kita-ku,
Sapporo, Hokkaido
060-0810,
Japan
11
Asahikawa Campus, Hokkaido University of Education, Hokumon,
Asahikawa, Hokkaido
070-8621,
Japan
12
INAF – Osservatorio Astronomico di Roma,
Via Frascati 33,
00078
Monte Porzio Catone,
Italy
13
Korea Astronomy and Space Science Institute (KASI),
776 Daedeok-daero,
Yuseong-gu, Daejeon
34055,
Republic of Korea
14
Physics Program, Graduate School of Advanced Science and Engineering, Hiroshima University,
1-3-1 Kagamiyama,
Higashi-Hiroshima, Hiroshima
739-8526,
Japan
15
Department of Physics, Okayama University of Science,
1-1 Ridai-cho, Kita-ku,
Okayama, Okayama
700-0005,
Japan
★ Corresponding author; e-mail: ishiguro@snu.ac.kr
Received:
23
June
2024
Accepted:
16
August
2024
Context. (4015) Wilson-Harrington (hereafter, WH) was discovered as a comet in 1949 but has a dynamical property consistent with that of a near-Earth asteroid. Although there is a report that the 1949 activity is associated with an ion tail, the cause of the activity has not yet been identified.
Aims. This work aims to reveal the mysterious comet-like activity of the near-Earth asteroid.
Methods. We conducted new polarimetric observations of WH from May 2022 to January 2023, reanalyses of the photographic plate images taken at the time of its discovery in 1949, and dust tail simulation modelings, where the dust terminal velocity and ejection epoch are taken into account.
Results. We found that this object shows polarization characteristics similar to those of low-albedo asteroids. We derived the geometric albedo ranging from pV = 0.076 ± 0.010 to pV = 0.094 ± 0.018 from our polarimetry (the values vary depending on the data used for fitting and the slope-albedo relationship coefficients). In addition, the 1949 image showed an increase in brightness around the nucleus. Furthermore, we found that the color of the tail is consistent with sunlight, suggesting that the 1949 activity is associated with dust ejection. From the dust tail analysis, ~9 × 105 kg of material was ejected episodically at a low velocity equivalent to or even slower than the escape velocity.
Conclusions. We conclude that WH is most likely an active asteroid of main belt origin and that the activity in 1949 was likely triggered by mass shedding due to fast rotation.
Key words: interplanetary medium / minor planets, asteroids: individual: 4015 Wilson–Harrington / comets: individual: 107P/Wilson–Harrington
© The Authors 2024
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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