45 Eugenia is a large asteroid of the asteroid belt. It is famed as one of the first asteroids to be found to have a moon orbiting it. It was also the second triple asteroid to be discovered, after 87 Sylvia.
 | |
| Discovery[1] | |
|---|---|
| Discovered by | H. Goldschmidt |
| Discovery date | 27 June 1857 |
| Designations | |
| (45) Eugenia | |
| Pronunciation | /juːˈdʒiːniə/[2] |
Named after | Empress Eugénie |
| 1941 BN | |
| Main belt | |
| Adjectives | Eugenian |
| Orbital characteristics[3] | |
| Epoch 26 November 2005 (JD 2453701.5) | |
| Aphelion | 440.305 Gm (2.943 AU) |
| Perihelion | 373.488 Gm (2.497 AU) |
| 406.897 Gm (2.720 AU) | |
| Eccentricity | 0.082 |
| 1638.462 d (4.49 a) | |
| 45.254° | |
| Inclination | 6.610° |
| 147.939° | |
| 85.137° | |
| Known satellites | Petit-Prince S/2004 (45) 1 |
| Physical characteristics | |
| Dimensions | 232 × 193 × 161 km[4] 305 × 220 × 145 km[5][6] |
| 94±1 km[7] 107.3±2.1 km[5] | |
| Mass | (5.8±0.1)×1018 kg[7] (5.69±0.1)×1018 kg[4] (5.8±0.2)×1018 kg[8][9][a] |
Mean density | 1.66±0.07 g/cm3[7] 1.1±0.1 g/cm3[4] 1.1±0.3 g/cm3[9] |
Equatorial surface gravity | 0.017 m/s²[b] |
Equatorial escape velocity | 0.071 km/s[b] |
| 0.2375 d (5.699 h)[10] | |
| 117±10° | |
Pole ecliptic latitude | −30±10°[6] |
Pole ecliptic longitude | 124±10° |
| 0.065 (calculated)[7] 0.040±0.002[5] | |
| F[11] | |
| 7.46[5] | |
Discovery
editEugenia was discovered on 27 June 1857 by the Franco-German amateur astronomer Hermann Goldschmidt.[12] His instrument of discovery was a 4-inch aperture telescope located in his sixth floor apartment in the 6th Arrondissement of Paris.[13] It was the forty-fifth minor planet to be discovered. The preliminary orbital elements were computed by Wilhelm Forster in Berlin, based on three observations in July, 1857.[14]
The asteroid was named by its discoverer after Empress Eugenia di Montijo, the wife of Napoleon III.[12] It was the first asteroid to be definitely named after a real person, rather than a figure from classical legend.[15]
Physical characteristics
editEugenia is a large asteroid, with a diameter of 214 km. It is an F-type asteroid, which means that it is very dark in colouring (darker than soot) with a carbonaceous composition. Like Mathilde, its density appears to be unusually low, indicating that it may be a loosely packed rubble pile, not a monolithic object. Eugenia appears to be almost anhydrous.[16] Lightcurve analysis indicates that Eugenia's pole most likely points towards ecliptic coordinates (β, λ) = (-30°, 124°) with a 10° uncertainty,[6] which gives it an axial tilt of 117°. Eugenia's rotation is then retrograde, rotating backward to its orbital plane.
Satellite system
editPetit-Prince
editIn November 1998, astronomers at the Canada-France-Hawaii Telescope on Mauna Kea, Hawaii, discovered a small moon orbiting Eugenia. This was the first time an asteroid moon had been discovered by a ground-based telescope. The moon is much smaller than Eugenia, about 13 km in diameter, and takes five days to complete an orbit around it.
The discoverers chose the name "Petit-Prince" (formally "(45) Eugenia I Petit-Prince"). This name refers to Empress Eugenia's son, the Prince Imperial. However, the discoverers also intended an allusion to the children's novella The Little Prince by Antoine de Saint-Exupéry, which is about a young prince who lives on an asteroid.[17]
S/2004 (45) 1
editA second, smaller (estimated diameter of 6 km) satellite that orbits closer to Eugenia than Petit-Prince has since been discovered and provisionally named S/2004 (45) 1.[18] It was discovered by analyses of three images acquired in February 2004 from the 8.2 m VLT "Yepun" at the European Southern Observatory (ESO) Cerro Paranal, in Chile.[19] The discovery was announced in IAUC 8817, on 7 March 2007 by Franck Marchis and his IMCCE collaborators. It orbits the asteroid at about ~700 km, with an orbital period of 4.7 days.[18]
Notes
edit- ^ Uncertainty calculated from uncertainties in the orbit of Petit-Prince.
- ^ a b On the extremities of the long axis.
See also
edit- Dactyl and Ida, another asteroid and asteroid moon system catalogued by astronomers
- Florence, another dual-moon asteroid confirmed only in September 2017.
References
edit- ^ "Discovery Circumstances: Numbered Minor Planets". IAU Minor Planet Center. Harvard-Smithsonian Center for Astrophysics. 9 February 2010. Archived from the original on 10 May 2008. Retrieved 12 August 2010.
- ^ "Eugenia". Oxford English Dictionary (Online ed.). Oxford University Press. (Subscription or participating institution membership required.)
- ^ "ASTORB". Orbital elements database. Lowell Observatory.
- ^ a b c Baer, Jim (2008). "Recent Asteroid Mass Determinations". Personal Website. Archived from the original on 2 July 2013. Retrieved 7 December 2008.
- ^ a b c d "Supplemental IRAS minor planet survey". Planetary Science Institute. Archived from the original on 17 August 2009.
- ^ a b c Kaasalainen, M.; et al. (2002). "Models of Twenty Asteroids from Photometric Data" (PDF). Icarus. 159 (2): 369–395. Bibcode:2002Icar..159..369K. doi:10.1006/icar.2002.6907.
- ^ a b c d P. Vernazza et al. (2021) VLT/SPHERE imaging survey of the largest main-belt asteroids: Final results and synthesis. Astronomy & Astrophysics 54, A56
- ^ Marchis, F. "synthesis of several observations". Berkeley. Archived from the original on 13 September 2006.
- ^ a b Marchis, F.; et al. (2004). "Fine Analysis of 121 Hermione, 45 Eugenia, and 90 Antiope Binary Asteroid Systems With AO Observations". Bulletin of the American Astronomical Society. 36: 1180. Bibcode:2004DPS....36.4602M.
- ^ "PDS lightcurve data". Planetary Science Institute. Archived from the original on 9 April 2009.
- ^ "PDS node taxonomy database". Planetary Science Institute. Archived from the original on 5 August 2009.
- ^ a b Schmadel, Lutz D. (2003). Dictionary of minor planet names. Physics and astronomy online library (5th ed.). Springer. p. 19. ISBN 3-540-00238-3.
- ^ J. C. (1867). "Obituary: Herman Goldschmidt". Memoirs of the Royal Astronomical Society. 36: 114–117. Retrieved 13 August 2010.
- ^ Goldschmidt, H. (July 1857). "New Planet (45)". Monthly Notices of the Royal Astronomical Society. 17: 263–264. Bibcode:1857MNRAS..17..263G. doi:10.1093/mnras/17.9.263b.
- ^ Tobin, William (2003). The life and science of Léon Foucault: the man who proved the earth rotates. Cambridge University Press. p. 301. ISBN 0-521-80855-3.
- ^ A. S. Rivkin (2002). "Calculated Water Concentrations on C Class Asteroids" (PDF). Lunar and Planetary Institute. Retrieved 22 May 2008.
- ^ William J. Merlin et al., "On a Permanent Name for Asteroid S/1998(45)1". 26 May 2000.
- ^ a b Marchis, F.; Baek, M.; Descamps, P.; Berthier, J.; Hestroffer, D.; Vachier, F. (2007). "S/2004 (45) 1". IAU Circular. 8817: 1. Bibcode:2007IAUC.8817....1M.
- ^ "IMCCÉ Breaking News". Archived from the original on 27 September 2007. Retrieved 30 April 2019.
External links
edit- Johnston Archive data
- Astronomical Picture of Day 14 October 1999
- SwRI Press Release
- Orbit of Petit-Prince, companion of Eugenia
- Shape model derived from lightcurve (on page 17)
- 14 frames of (45) Eugenia primary taken with the Keck II AO from Dec 2003 to Nov 2011 (Franck Marchis)
- 45 Eugenia at AstDyS-2, Asteroids—Dynamic Site
- 45 Eugenia at the JPL Small-Body Database
