45 Eugenia
CFHT time-lapse image of Eugenia and Petit-Prince, showing five stages in the moon's orbit. The 'flare' around them is an imaging artifact
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Discovery[1] | |||||||||||||
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Discovered by | H. Goldschmidt | ||||||||||||
Discovery date | 27 June 1857 | ||||||||||||
Designations | |||||||||||||
Pronunciation | /juːˈdʒiːniə/ ew-JEE-nee-ə | ||||||||||||
Named after
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Empress Eugénie | ||||||||||||
1941 BN | |||||||||||||
Main belt | |||||||||||||
Orbital characteristics[2] | |||||||||||||
Epoch November 26, 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) | |||||||||||||
Average orbital speed
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18.03 km/s | ||||||||||||
45.254° | |||||||||||||
Inclination | 6.610° | ||||||||||||
147.939° | |||||||||||||
85.137° | |||||||||||||
Known satellites | Petit-Prince S/2004 (45) 1 |
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Physical characteristics | |||||||||||||
Dimensions | 232 × 193 × 161 km[3] 305 × 220 × 145 km[4][5] |
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Mean radius
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107.3 ± 2.1 km[4] | ||||||||||||
Mass | (5.69 ± 0.1) ×1018 kg[3] (5.8 ± 0.2) ×1018 kg[6][7][8] |
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Mean density
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1.1 ± 0.1 g/cm³[3] 1.1 ± 0.3 g/cm³[7] |
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Equatorial surface gravity
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0.017 m/s²[9] | ||||||||||||
Equatorial escape velocity
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0.071 km/s[9] | ||||||||||||
Sidereal rotation period
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0.2375 d (5.699 h)[10] | ||||||||||||
117 ± 10° | |||||||||||||
Pole ecliptic latitude
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-30 ± 10°[5] | ||||||||||||
Pole ecliptic longitude
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124 ± 10° | ||||||||||||
0.040 ± 0.002[4] | |||||||||||||
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F[11] | |||||||||||||
7.46[4] | |||||||||||||
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 is also the second known triple asteroid, after 87 Sylvia.
Contents
Discovery
Eugenia was discovered on June 28, 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 Latin Quarter 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] although there was some controversy about whether 12 Victoria was really named for the mythological figure or for Queen Victoria.[citation needed]
Physical characteristics
Eugenia 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,[5] which gives it an axial tilt of 117°. Eugenia's rotation is then retrograde.
Satellite system
Petit-Prince
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In 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
A 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]
See also
- Dactyl and Ida, another asteroid and asteroid moon system catalogued by astronomers
References
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- ↑ 7.0 7.1 Lua error in package.lua at line 80: module 'strict' not found.
- ↑ Uncertainty calculated from uncertainties in the orbit of Petit-Prince.
- ↑ 9.0 9.1 On the extremities of the long axis.
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- ↑ 12.0 12.1 Lua error in package.lua at line 80: module 'strict' not found.
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- ↑ William J. Merlin et al, "On a Permanent Name for Asteroid S/1998(45)1". May 26, 2000.
- ↑ 18.0 18.1 http://adsabs.harvard.edu/abs/2007IAUC.8817....1M IAUC 8817
- ↑ IMCCÉ Breaking News
External links
- Pages with reference errors
- Articles with unsourced statements from August 2010
- Main-belt asteroids
- C-type asteroids (SMASS)
- Fc-type asteroids (Tholen)
- Trinary minor planets
- Asteroids named for people
- House of Bonaparte
- Astronomical objects discovered in 1857
- Antoine de Saint-Exupéry
- Discoveries by Hermann Goldschmidt
- Numbered asteroids