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29 Amphitrite

VLT image of Amphitrite
Discovery
Discovered by	A. Marth
Discovery site	London
Discovery date	1 March 1854
Designations
MPC designation	(29) Amphitrite
Pronunciation	/æmfɪˈtraɪtiː/
Named after	Amphitrite (Greek mythology)
Alternative designations	A899 NG
Minor planet category	main-belt · (middle) background
Adjectives	Amphitritean /ˌæmfɪtrɪˈtiːən/, /ˌæmfɪˈtraɪtiən/
Symbol	(historical)
Orbital characteristics
Epoch 17.0 October 2024 (JD 2460600.5)
Uncertainty parameter 0
Observation arc	169.16 yr (61,784 d)
Aphelion	2.7425 AU
Perihelion	2.3664 AU
Semi-major axis	2.5544 AU
Eccentricity	0.0736
Orbital period (sidereal)	4.08 yr (1491 d)
Mean anomaly	48.40°
Mean motion	0° 14 29.04 / day
Inclination	6.0772°
Longitude of ascending node	356.26°
Argument of perihelion	62.01°
Earth MOID	1.38454 AU
Jupiter MOID	2.48544 AU
TJupiter	3.427
Physical characteristics
Dimensions	233 km × 212 km × 193 km 222 km × 209 km × 183 km (± 6 km × 6 km × 5 km)
Mean diameter	204±2 km 189.6±1.1 km 196±22 km 206.86 km 212.22±6.8 km 227.1±4.0 km
Flattening	0.18
Mass	(12.7±2.0)×10 kg (11.8 ± ?)×10 kg
Mean density	2.86±0.45 g/cm 2.36±0.26 g/cm
Synodic rotation period	5.3921 h 5.390119 ± 0.000001 h
Axial tilt	116°
Pole ecliptic latitude	−29°±2°
Pole ecliptic longitude	323°±2°
Geometric albedo	0.194 0.157±0.035 0.1793±0.012 0.195 0.216±0.043
Spectral type	S
Absolute magnitude (H)	5.85 5.98 6.0

29 Amphitrite is one of the largest S-type asteroids, approximately 200 kilometers (120 miles) in diameter, and probably fifth largest after Eunomia, Juno, Iris and Herculina.

Discovery

Amphitrite was discovered by Albert Marth on 1 March 1854, at the private South Villa Observatory, in Regent's Park, London. It was Marth's only asteroid discovery. Its name was chosen by George Bishop, the owner of the observatory, who named it after Amphitrite, a sea goddess in Greek mythology. Its historical symbol was a shell and star; it is in the pipeline for Unicode 17.0 as U+1CECF 𜻏 ().

Characteristics

Amphitrite's orbit is less eccentric and inclined than those of its larger cousins; indeed, it is the most circular of any asteroid discovered up to that point. As a consequence, it never becomes as bright as Iris or Hebe, especially as it is much further from the Sun than those asteroids. It can reach magnitudes of around +8.6 at a favorable opposition, but usually is around the binocular limit of +9.5.

In 2007, James Baer and Steven R. Chesley estimated Amphitrite to have a mass of 1.9×10 kg. A 2008 estimate by Baer suggests it has a mass of 1.18×10 kg.

A satellite of the asteroid is suspected to exist, based on lightcurve data collected by Edward F. Tedesco. In 1988 a search for satellites or dust orbiting this asteroid was performed using the UH88 telescope at the Mauna Kea Observatories, but neither were found.

Proposed exploration

In 1984, while determining the Galileo mission's prelaunch trajectory to Jupiter, JPL engineers found out that if the spacecraft launched on May 1986, it could perform a flyby of 29 Amphitrite at a distance of 6,200 mi (10,000 km) on December 1, 1986. However, with the Challenger disaster delaying the launch to October 1989, the flyby was ultimately cancelled.

Notes

1. Flattening derived from the maximum aspect ratio (c/a): ${\displaystyle f=1-{\frac {c}{a}}}$, where (c/a) = 0.82±0.03.

References

1. ^ "29 Amphitrite". Minor Planet Center. Retrieved 1 June 2018.
2. Noah Webster (1884) A Practical Dictionary of the English Language
3. ^ Schmadel, Lutz D. (2007). "(29) Amphitrite". Dictionary of Minor Planet Names – (29) Amphitrite. Springer Berlin Heidelberg. p. 18. doi:10.1007/978-3-540-29925-7_30. ISBN 978-3-540-00238-3.
4. ^ "JPL Small-Body Database Browser: 29 Amphitrite" (2024-09-20 last obs.). Jet Propulsion Laboratory. Retrieved 22 December 2024.
5. ^ "Asteroid (29) Amphitrite". AstDyS-2, Asteroids – Dynamic Site. Retrieved 25 May 2018.
6. ^ "Asteroid 29 Amphitrite". Small Bodies Data Ferret. Retrieved 1 June 2018.
7. ^ Jim Baer (2008). "Recent Asteroid Mass Determinations". Personal Website. Archived from the original on 2 July 2013. Retrieved 27 November 2008.
8. ^ P. Vernazza et al. (2021) VLT/SPHERE imaging survey of the largest main-belt asteroids: Final results and synthesis. Astronomy & Astrophysics 54, A56
9. ^ Masiero, Joseph R.; Grav, T.; Mainzer, A. K.; Nugent, C. R.; Bauer, J. M.; Stevenson, R.; et al. (August 2014). "Main-belt Asteroids with WISE/NEOWISE: Near-infrared Albedos". The Astrophysical Journal. 791 (2): 11. arXiv:1406.6645. Bibcode:2014ApJ...791..121M. doi:10.1088/0004-637X/791/2/121. S2CID 119293330.
10. Hanus, J.; Marchis, F.; Durech, J. (September 2013). "Sizes of main-belt asteroids by combining shape models and Keck adaptive optics observations". Icarus. 226 (1): 1045–1057. arXiv:1308.0446. Bibcode:2013Icar..226.1045H. doi:10.1016/j.icarus.2013.07.023. S2CID 118710558.
11. ^ Usui, Fumihiko; Kuroda, Daisuke; Müller, Thomas G.; Hasegawa, Sunao; Ishiguro, Masateru; Ootsubo, Takafumi; et al. (October 2011). "Asteroid Catalog Using Akari: AKARI/IRC Mid-Infrared Asteroid Survey". Publications of the Astronomical Society of Japan. 63 (5): 1117–1138. Bibcode:2011PASJ...63.1117U. doi:10.1093/pasj/63.5.1117. (online, AcuA catalog p. 153)
12. ^ Tedesco, E. F.; Noah, P. V.; Noah, M.; Price, S. D. (October 2004). "IRAS Minor Planet Survey V6.0". NASA Planetary Data System. 12: IRAS-A-FPA-3-RDR-IMPS-V6.0. Bibcode:2004PDSS...12.....T. Retrieved 22 October 2019.
13. ^ Mainzer, A.; Grav, T.; Masiero, J.; Hand, E.; Bauer, J.; Tholen, D.; et al. (November 2011). "NEOWISE Studies of Spectrophotometrically Classified Asteroids: Preliminary Results". The Astrophysical Journal. 741 (2): 25. arXiv:1109.6407. Bibcode:2011ApJ...741...90M. doi:10.1088/0004-637X/741/2/90. S2CID 118700974. (catalog)
14. "LCDB Data for (29) Amphitrite". Asteroid Lightcurve Database (LCDB). Retrieved 1 June 2018.
15. Bala, Gavin Jared; Miller, Kirk (18 September 2023). "Unicode request for historical asteroid symbols" (PDF). unicode.org. Unicode. Retrieved 26 September 2023.
16. Unicode. "Proposed New Characters: The Pipeline". unicode.org. The Unicode Consortium. Retrieved 6 November 2023.
17. Baer, James; Steven R. Chesley (2008). "Astrometric masses of 21 asteroids, and an integrated asteroid ephemeris". Celestial Mechanics and Dynamical Astronomy. 100 (2008): 27–42. Bibcode:2008CeMDA.100...27B. doi:10.1007/s10569-007-9103-8.
18. Tedesco, E. F. (March 1979). "Binary Asteroids: Evidence for Their Existence from Lightcurves". Science. New Series. 203 (4383): 905–907. Bibcode:1979Sci...203..905T. doi:10.1126/science.203.4383.905. PMID 17771729. S2CID 19431574.
19. van Flandern, T. C.; Tedesco, E. F.; Binzel, R. P. (1979). "Satellites of asteroids". Asteroids. Tucson, AZ: University of Arizona Press. pp. 443–465. Bibcode:1979aste.book..443V.
20. Gradie, J.; Flynn, L. (March 1988), "A Search for Satellites and Dust Belts Around Asteroids: Negative Results", Abstracts of the Lunar and Planetary Science Conference, vol. 19, pp. 405–406, Bibcode:1988LPI....19..405G
21. Murray, B. C. (1989). Journey Into Space: The First Three Decades of Space Exploration. Norton & Company. p. 222. ISBN 0-393-02675-2.

External links

• Discovery Circumstances: Numbered Minor Planets (1)-(5000) – Minor Planet Center
• 29 Amphitrite at AstDyS-2, Asteroids—Dynamic Site
  • Ephemeris · Observation prediction · Orbital info · Proper elements · Observational info
• 29 Amphitrite at the JPL Small-Body Database
  • Close approach · Discovery · Ephemeris · Orbit viewer · Orbit parameters · Physical parameters

• Minor planet object articles (numbered)
• Background asteroids
• Discoveries by Albert Marth
• Named minor planets
• S-type asteroids (Tholen)
• S-type asteroids (SMASS)
• Astronomical objects discovered in 1854