269 Justitia
 Shape of Justitia as seen by stellar occultation observations on 31 August 2023 | |
| Discovery | |
|---|---|
| Discovered by | Johann Palisa |
| Discovery date | 21 September 1887 |
| Designations | |
| (269) Justitia | |
| Pronunciation | /dʒʌˈstɪʃiə/[1] |
Named after | Justitia |
| A887 SA, 1942 XY | |
| Main belt | |
| Orbital characteristics[2] | |
| Epoch 31 July 2016 (JD 2457600.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 126.16 yr (46080 d) |
| Aphelion | 3.17477 AU (474.939 Gm) |
| Perihelion | 2.0555 AU (307.50 Gm) |
| 2.61515 AU (391.221 Gm) | |
| Eccentricity | 0.21399 |
| 4.23 yr (1544.7 d) | |
| 219.582° | |
| 0° 13m 59.016s / day | |
| Inclination | 5.4799° |
| 156.759° | |
| 119.62° | |
| Physical characteristics | |
| Dimensions | 53.62±1.3 km |
| 33.128 h (1.3803 d) | |
| 0.0974±0.005 | |
| 9.7 | |
269 Justitia is a dark, fairly sizeable asteroid located in the main asteroid belt. It is around 58 kilometres (36 mi) in diameter and rotates relatively slowly, with a rotation period of around 33.1 hours. It was discovered by Johann Palisa on 21 September 1887 in Vienna. The asteroid was named after Justitia, the Roman equivalent of Themis, the Greek goddess of justice (she also has an asteroid named after her, 24 Themis).
Physical characteristics
[edit]
Spectroscopic observations of Justitia indicate that it is a spectrally red carbonaceous asteroid. Its surface is very dark, with a geometric albedo of 0.061±0.007.[3] Thermal modelling of the asteroid indicates that it is around 58 km (36 mi) in diameter, with a very rough surface.[4] In the Bus-DeMeo classification scheme, Justitia is categorized as a D-type asteroid; the Small Main-belt Asteroid Spectroscopic Survey, Phase II (SMASSII) classification scheme alternatively classifies it as an Ld-type asteroid. More recently, in 2022, a team of astronomers led by M. Mahlke proposed a new Z-type classification within which Justitia belongs to.[3] Z-type asteroids are similar to D-type asteroids, but are distinguished by their strong spectrally red colors and distinct orbital characteristics.[5]
Justitia's extreme redness is shared with the mid-sized asteroid 203 Pompeja. Spectroscopic analysis of the two asteroids suggests the presence of complex organic materials—tholins—and other undetermined and spectroscopically featureless materials on their surfaces. Based on their spectroscopic similarities to small outer Solar System objects—trans-Neptunian objects (TNOs) and centaurs—a team of astronomers led by Sunao Hasegawa argued that the two asteroids may have originated from the primordial Kuiper belt before later migrating to the main asteroid belt.[6]
On 31 August 2023, Justitia occulted a background star, with multiple observation teams successfully observing the event. This allowed for the direct determination of its size and shape. The occultation revealed that Justitia has a volume-equivalent diameter of 57.0 km (35.4 mi) or 57.8 km (35.9 mi), with the larger value being preferred by Marc Buie et al. Justitia was revealed to be highly irregular in shape, with at least three large facets 23–38 km (14–24 mi) in length being observed.[3]
Exploration
[edit]Justitia is planned to be the seventh and final target of the United Arab Emirates' MBR Explorer mission, which will attempt to land on its surface in 2034.[7][8]
References
[edit]- ^ "justitium". Oxford English Dictionary (Online ed.). Oxford University Press. (Subscription or participating institution membership required.)
- ^ "269 Justitia". JPL Small-Body Database. NASA/Jet Propulsion Laboratory. Retrieved 11 May 2016.
- ^ a b c Buie, Marc W.; et al. (18 March 2025). "Occultation-based Size and Shape of (269) Justitia". The Planetary Science Journal. 6. doi:10.3847/PSJ/adb28c.
- ^ Marciniak, Anna; et al. (18 March 2025). "Thermophysical Model of (269) Justitia—Main Belt Asteroid Possibly Implanted from Trans-Neptunian Region". The Planetary Science Journal. 6. doi:10.3847/PSJ/adb28b.
- ^ Mahlke, M.; Carry, B.; Mattei, P. -A. (September 2022). "Asteroid taxonomy from cluster analysis of spectrometry and albedo". Astronomy & Astrophysics. 665. arXiv:2203.11229. Bibcode:2022A&A...665A..26M. doi:10.1051/0004-6361/202243587. A26.
- ^ Hasegawa, Sunao; Marsset, Michaël; Demeo, Francesca E.; Bus, Schelte J.; Geem, Jooyeon; Ishiguro, Masateru; Im, Myungshin; Kuroda, Daisuke; Vernazza, Pierre (2021). "Discovery of two TNO-like bodies in the asteroid belt". The Astrophysical Journal Letters. 916 (1): L6. arXiv:2106.14991. Bibcode:2021ApJ...916L...6H. doi:10.3847/2041-8213/ac0f05. S2CID 235669878.
- ^ "UAE announces space mission to land MBR Explorer on asteroid 5 billion kilometres away". Arabian Business. 29 May 2023. Retrieved 14 June 2023.
- ^ "Touring Through the Asteroid Belt: United Arab Emirates Unveils Bold Mission". SpaceRef. 29 May 2023. Retrieved 14 June 2023.
- The Asteroid Orbital Elements Database
- Minor Planet Discovery Circumstances
- Asteroid Lightcurve Data File
External links
[edit]- 269 Justitia at AstDyS-2, Asteroids—Dynamic Site
- 269 Justitia at the JPL Small-Body Database
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