45 Eugenia

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45 Eugenia
45 Eugenia VLT (2021), deconvolved.pdf
Discovery [1]
Discovered by H. Goldschmidt
Discovery date27 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
Dimensions232 × 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] [lower-alpha 1]
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 [lower-alpha 2]
Equatorial escape velocity
0.071 km/s [lower-alpha 2]
0.2375 d (5.699 h) [10]
117±10°
−30±10° [6]
124±10°
0.065 (calculated) [7]
0.040±0.002 [5]
F [11]
7.46 [5]

    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.

    Contents

    Discovery

    Eugenia 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

    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, [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. [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]

    Notes

    1. ↑ Uncertainty calculated from uncertainties in the orbit of Petit-Prince.
    2. 1 2 On the extremities of the long axis.

    See also

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    References

    1. ↑ "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.
    2. ↑ "Eugenia" . Oxford English Dictionary (Online ed.). Oxford University Press.(Subscription or participating institution membership required.)
    3. ↑ "ASTORB". Orbital elements database. Lowell Observatory.
    4. 1 2 3 Baer, Jim (2008). "Recent Asteroid Mass Determinations". Personal Website. Archived from the original on 2 July 2013. Retrieved 7 December 2008.
    5. 1 2 3 4 "Supplemental IRAS minor planet survey". Planetary Science Institute. Archived from the original on 17 August 2009.
    6. 1 2 3 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.
    7. 1 2 3 4 P. Vernazza et al. (2021) VLT/SPHERE imaging survey of the largest main-belt asteroids: Final results and synthesis. Astronomy & Astrophysics 54, A56
    8. ↑ Marchis, F. "synthesis of several observations". Berkeley. Archived from the original on 13 September 2006.
    9. 1 2 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.
    10. ↑ "PDS lightcurve data". Planetary Science Institute. Archived from the original on 9 April 2009.
    11. ↑ "PDS node taxonomy database". Planetary Science Institute. Archived from the original on 5 August 2009.
    12. 1 2 Schmadel, Lutz D. (2003). Dictionary of minor planet names . Physics and astronomy online library (5th ed.). Springer. p.  19. ISBN   3-540-00238-3.
    13. ↑ J. C. (1867). "Obituary: Herman Goldschmidt". Memoirs of the Royal Astronomical Society. 36: 114–117. Retrieved 13 August 2010.
    14. ↑ 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 .
    15. ↑ 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.
    16. ↑ A. S. Rivkin (2002). "Calculated Water Concentrations on C Class Asteroids" (PDF). Lunar and Planetary Institute. Retrieved 22 May 2008.
    17. ↑ William J. Merlin et al., "On a Permanent Name for Asteroid S/1998(45)1". 26 May 2000.
    18. 1 2 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.
    19. ↑ "IMCCÉ Breaking News". Archived from the original on 27 September 2007. Retrieved 30 April 2019.
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