Sunho Jin, Masateru Ishiguro, Jooyeon Geem, Hiroyuki Naito, Jun Takahashi, Hiroshi Akitaya, Daisuke Kuroda, Seitaro Urakawa, Seiko Takagi, Tatsuharu Oono, Tomohiko Sekiguchi, Davide Perna, Simone Ieva, Yoonsoo P. Bach, Ryo Imazawa, Koji S. Kawabata, Makoto Watanabe, Hangbin Jo
{"title":"New evidence supporting past dust ejections from active asteroid (4015) Wilson–Harrington","authors":"Sunho Jin, Masateru Ishiguro, Jooyeon Geem, Hiroyuki Naito, Jun Takahashi, Hiroshi Akitaya, Daisuke Kuroda, Seitaro Urakawa, Seiko Takagi, Tatsuharu Oono, Tomohiko Sekiguchi, Davide Perna, Simone Ieva, Yoonsoo P. Bach, Ryo Imazawa, Koji S. Kawabata, Makoto Watanabe, Hangbin Jo","doi":"10.1051/0004-6361/202451225","DOIUrl":null,"url":null,"abstract":"<i>Context.<i/> (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.<i>Aims.<i/> This work aims to reveal the mysterious comet-like activity of the near-Earth asteroid.<i>Methods.<i/> 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.<i>Results.<i/> We found that this object shows polarization characteristics similar to those of low-albedo asteroids. We derived the geometric albedo ranging from <i>p<sub>V<sub/><i/> = 0.076 ± 0.010 to <i>p<sub>V<sub/><i/> = 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 × 10<sup>5<sup/> kg of material was ejected episodically at a low velocity equivalent to or even slower than the escape velocity.<i>Conclusions.<i/> 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.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":null,"pages":null},"PeriodicalIF":5.4000,"publicationDate":"2024-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Astronomy & Astrophysics","FirstCategoryId":"101","ListUrlMain":"https://doi.org/10.1051/0004-6361/202451225","RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"ASTRONOMY & ASTROPHYSICS","Score":null,"Total":0}
引用次数: 0
Abstract
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.
期刊介绍:
Astronomy & Astrophysics is an international Journal that publishes papers on all aspects of astronomy and astrophysics (theoretical, observational, and instrumental) independently of the techniques used to obtain the results.