astro.wikisort.org - Asteroid

Eugenia (minor planet designation: 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.

45 Eugenia

Discovery[1]
Discovered by	H. Goldschmidt
Discovery date	27 June 1857
Designations
MPC designation	(45) Eugenia
Pronunciation	/juːˈdʒiːniə/[2]
Named after	Empress Eugénie
Alternative designations	1941 BN
Minor planet category	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)
Semi-major axis	406.897 Gm (2.720 AU)
Eccentricity	0.082
Orbital period (sidereal)	1638.462 d (4.49 a)
Mean anomaly	45.254°
Inclination	6.610°
Longitude of ascending node	147.939°
Argument of perihelion	85.137°
Known satellites	Petit-Prince S/2004 (45) 1
Physical characteristics
Dimensions	232 × 193 × 161 km[4] 305 × 220 × 145 km[5][6]
Mean radius	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][10]
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[11]
Equatorial escape velocity	0.071 km/s[11]
Sidereal rotation period	0.2375 d (5.699 h)[12]
Axial tilt	117±10°
Pole ecliptic latitude	−30±10°[6]
Pole ecliptic longitude	124±10°
Geometric albedo	0.065 (calculated)[7] 0.040±0.002[5]
Spectral type	F[13]
Absolute magnitude (H)	7.46[5]

Discovery

Eugenia was discovered on 27 June 1857 by the Franco-German amateur astronomer Hermann Goldschmidt.[14] His instrument of discovery was a 4-inch aperture telescope located in his sixth floor apartment in the 6th Arrondissement of Paris.[15] 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.[16]

The asteroid was named by its discoverer after Empress Eugenia di Montijo, the wife of Napoleon III.[14] It was the first asteroid to be definitely named after a real person, rather than a figure from classical legend.[17]

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.[18] 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

Petit-Prince

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.[19]

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.[20] 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.[21] 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.[20]

See also

• Dactyl and Ida, another asteroid and asteroid moon system catalogued by astronomers
• Florence, another dual-moon asteroid confirmed only in September 2017.

References

External links

• 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
  • Ephemeris · Observation prediction · Orbital info · Proper elements · Observational info
• 45 Eugenia at the JPL Small-Body Database
  • Close approach · Discovery · Ephemeris · Orbit diagram · Orbital elements · Physical parameters

На других языках

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[de] (45) Eugenia

(45) Eugenia ist ein Asteroid des Asteroiden-Hauptgürtels. Mit einem Durchmesser von 202 km ist Eugenia einer der größten Asteroiden des Hauptgürtels.

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- [en] 45 Eugenia

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[es] (45) Eugenia

(45) Eugenia es un asteroide perteneciente al cinturón de asteroides descubierto el 27 de junio de 1857 por Hermann Mayer Salomon Goldschmidt desde París, Francia. Está nombrado en honor de la emperatriz francesa de origen español Eugenia de Montijo.[2]

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[ru] (45) Евгения

(45) Евгения (лат. Eugenia) — астероид главного пояса, который принадлежит к редкому спектральному классу F. Главной особенностью астероида (45) Евгения является то, что он стал одним из первых астероидов, у которых был обнаружен спутник, и вторым, после (87) Сильвия, астероидом, который был признан тройным[11].

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