双卫一近地天体双生星的一颗卫星。它的直径为170米(560英尺),与罗马斗兽场相当,重约480万吨。它与双生星中心相距约1190米[7]。2003年,有人在翁德热约夫天文台发现了双卫一。2020年6月,国际天文联会将这颗小行星卫星命名为双卫一[8]。2022年9月,美国太空总署在开展双小行星改道测试时将双卫一列为撞击目标,并故意让一个航天器撞向双卫一,目的是改变双卫一的轨迹[9]

双卫一
摄于2022年9月
发现[1]
发现者Petr Pravec英语Petr Pravec et al.[a]
发现日期2003年11月20日
编号
其它名称S/2003 (65803) 1
轨道参数[2]
历元 7.5 2011年1月 (儒略日 2455873.0)
半长轴1.19±0.03 km (撞击前)
离心率≤ 0.03
轨道周期11.9216262±0.0000027 hr (11h 55m 18s; 撞击前)[2]
11h 23m ± 2m (撞击后)[3][b]
平均轨道速度0.174 m/s (撞击前)
平近点角89.2°±1.8°
轨道倾角168.6°±1.8° 相对于黄道[c]
隶属天体双生星
物理特征
大小208 米 × 160 米 × 133 米[6]
质量~5×109 kg (推测)[6]
自转周期潮汐锁定?
反照率0.15±0.04
光谱类型S-型小行星
绝对星等(H)21.3±0.2 [1]

备注

  1. ^ Astronomers involved in the discovery of Dimorphos include Petr Pravec英语Petr Pravec, L.A.M. Benner, M.C. Nolan, P. Kusnirak, D. Pray, J.D. Giorgini, R.F. Jurgens, 史蒂文·J·奥斯特罗, J.-L. Margot, C. Magri, A. Grauer, and S. Larson. The discovery used lightcurve and radar observations from the 喷气推进实验室, Pasadena, 加利福尼亚州; 阿雷西博天文台, Arecibo, 波多黎各; and 翁德热约夫天文台, Ondřejov, 捷克. [1]
  2. ^ Orbital parameters are those after the impact of DART, which changed the 轨道周期 by 32 minutes. Other possibly changed parameters remain to be reevaluated.[3]
  3. ^ Scheirich and Pravec (2022) give the Dimorphos's orbit pole orientation in terms of 黄道坐标系, where λ is 黄道坐标系 and β is 黄道坐标系.[4](p. 4) β is the angular offset from the 黄道, whereas 轨道倾角 i with respect to the ecliptic is the angular offset of the 黄极 from the 黄极, at β = +90° ; i with respect to the ecliptic would be the of β.[5] Therefore, given β = –78.6° , i = 90° – (–78.6°) = 168.6° from the ecliptic.

参考文献

  1. ^ 1.0 1.1 1.2 (65803) Didymos. www.johnstonsarchive.net. [2021-11-11]. (原始内容存档于2020-10-23). 
  2. ^ 2.0 2.1 Naidu, Shantanu P.; Chesley, Steven R.; Farnocchia, Davide; Moskovitz, Nick; Pravec, Petr; Scheirich, Petr; Thomas, Cristina; Rivkin, Andrew S. Anticipating the DART impact: Orbit estimation of Dimorphos using a simplified model. The Planetary Science Journal. October 2022, 3 (10): 234. Bibcode:2022PSJ.....3..234N. S2CID 252815897. arXiv:2210.05101 . doi:10.3847/PSJ/ac91c0. 
  3. ^ 3.0 3.1 Dunbar, Brian. NASA Confirms DART Mission Impact Changed Asteroid's Motion in Space. NASA. 11 October 2022 [2022-10-11]. (原始内容存档于2023-03-07) (英语). 
  4. ^ Scheirich, P.; Pravec, P. Preimpact Mutual Orbit of the DART Target Binary Asteroid (65803) Didymos Derived from Observations of Mutual Events in 2003–2021. The Planetary Science Journal. July 2022, 3 (7): 12 [2023-01-21]. Bibcode:2022PSJ.....3..163S. S2CID 250650906. doi:10.3847/PSJ/ac7233. 163. (原始内容存档于2022-07-19). 
  5. ^ Coordinate transformations. Astronomy and Astrophysics. European Southern Observatory. January 1998 [17 June 2022]. (原始内容存档于17 June 2021). 
  6. ^ 6.0 6.1 Nakano, Ryota; Hirabayashi, Masatoshi; Brozovic, M.; Nolan, M. C.; Ostro, S. J.; Margot, J. L.; et al. NASA's Double Asteroid Redirection Test (DART): Mutual Orbital Period Change Due to Reshaping in the Near-Earth Binary Asteroid System (65803) Didymos. The Planetary Science Journal. July 2022, 3 (7): 16 [2023-01-21]. Bibcode:2022PSJ.....3..148N. S2CID 250327233. doi:10.3847/PSJ/ac7566. 148. (原始内容存档于2022-09-27). 
  7. ^ 观网财经. 人类首次行星防御演习,成功了. [2023-01-21]. (原始内容存档于2023-03-08). 
  8. ^ Temming, Maria. An asteroid's moon got a name so NASA can bump it off its course. Science News. 29 June 2020 [1 July 2020]. (原始内容存档于2021-09-12). 
  9. ^ Rincon, Paul. NASA DART asteroid spacecraft: Mission to smash into Dimorphos space rock launches. BBC News. 2021-11-24 [2021-11-25]. (原始内容存档于2022-01-01) (英国英语).