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Alexandra (minor planet designation: 54 Alexandra) is a carbonaceous asteroid from the intermediate asteroid belt, approximately 155 kilometers in diameter. It was discovered by German-French astronomer Hermann Goldschmidt on 10 September 1858, and named after the German explorer Alexander von Humboldt; it was the first asteroid to be named after a male.[7]

54 Alexandra
A three-dimensional model of 54 Alexandra based on its light curve
Discovery[1]
Discovered byH. Goldschmidt
Discovery date10 September 1858
Designations
MPC designation
(54) Alexandra
Pronunciation/ælɪɡˈzændrə, -ˈzɑːn-/[2]
Named after
Alexander von Humboldt
(German explorer)
Minor planet category
Main belt
AdjectivesAlexandrian
Orbital characteristics
Epoch December 31, 2006 (JD 2454100.5)
Aphelion485.483 Gm (3.245 AU)
Perihelion326.043 Gm (2.179 AU)
Semi-major axis
405.763 Gm (2.712 AU)
Eccentricity0.196
Orbital period (sidereal)
1,631.620 d (4.47 a)
Mean anomaly
103.809°
Inclination11.804°
Longitude of ascending node
313.446°
Argument of perihelion
345.594°
Physical characteristics
Dimensions160 × 135 km (± 1 km)
Mean diameter
154.137 km[1]
Mass(6.16±3.50)×1018 kg[3]
Mean density
3.50±2.11 g/cm3[3]
Synodic rotation period
18.14 h[4]
Pole ecliptic latitude
155°±4°[5]
Pole ecliptic longitude
17°±3°[5]
Geometric albedo
0.056[1][6]
Spectral type
Tholen = C [1]
SMASS = C [1]
Absolute magnitude (H)
7.66[1]

    Description


    On May 17, 2005, this asteroid occulted a faint star (magnitude 8.5) and the event was observed and timed in a number of locations within the U.S. and Mexico. As a result, a silhouette profile was produced, yielding a roughly oval cross-section with dimensions of 160 × 135 km (± 1 km).[8] The mass of the asteroid can be estimated based upon the mutually perturbing effects of other bodies, yielding an estimate of (6.16±3.50)×1018 kg.[3]

    Photometric observations of this asteroid during 1990–92 gave a light curve with a period of 18.14 ± 0.04 hours and a brightness variation of 0.10 in magnitude.[4] Alexandra has been studied by radar.[9] It was the namesake and largest member of the former Alexandra asteroid family; a dynamic group of C-type asteroids that share similar orbital elements. Other members included 70 Panopaea and 145 Adeona.[10] 145 Adeona was subsequently assigned to the Adeona family, with Alexandra and Panopaea being dropped.[11]


    References


    1. Yeomans, Donald K. "54 Alexandra". JPL Small-Body Database Browser. NASA Jet Propulsion Laboratory. Retrieved 7 April 2013.
    2. "Alexandra". Lexico UK English Dictionary. Oxford University Press. Archived from the original on 22 March 2020.
      "Alexandra". Dictionary.com Unabridged (Online). n.d.
    3. Carry, B. (December 2012), "Density of asteroids", Planetary and Space Science, vol. 73, pp. 98–118, arXiv:1203.4336, Bibcode:2012P&SS...73...98C, doi:10.1016/j.pss.2012.03.009. See Table 1.
    4. Belskaya, I. N.; et al. (November 1993), "Physical Studies of Asteroids. Part XXVII. Photoelectric Photometry of Asteroids 14 Irene, 54 Alexandra and 56 Melete", Astronomy and Astrophysics Supplement, vol. 101, no. 3, pp. 507–511, Bibcode:1993A&AS..101..507B.
    5. Hanuš, J.; et al. (May 2017), "Volumes and bulk densities of forty asteroids from ADAM shape modeling", Astronomy & Astrophysics, 601: 41, arXiv:1702.01996, Bibcode:2017A&A...601A.114H, doi:10.1051/0004-6361/201629956, A114.
    6. "Asteroid Data Sets". Archived from the original on 17 December 2009. Retrieved 12 January 2007.
    7. Schmadel, Lutz D. (2003), Dictionary of Minor Planet Names (5th ed.), Springer, p. 20, ISBN 3642297188.
    8. D.W. Dunham, "Upcoming Asteroid Occultations", Sky & Telescope, June, 2006, p. 63.
    9. "Radar-Detected Asteroids and Comets". NASA/JPL Asteroid Radar Research. Retrieved 30 October 2011.
    10. Williams, J. G. (March 1988), "The Unusual Alexandra Family", Abstracts of the Lunar and Planetary Science Conference, vol. 19, pp. 1277–1278, Bibcode:1988LPI....19.1277W.
    11. Zappala, Vincenzo; et al. (December 1990), "Asteroid families. I - Identification by hierarchical clustering and reliability assessment", Astronomical Journal, vol. 100, pp. 2030–2046, 2045, Bibcode:1990AJ....100.2030Z, doi:10.1086/115658. See p. 2045 and family 44.



    На других языках

    [de] (54) Alexandra

    (54) Alexandra ist ein Asteroid des Asteroiden-Hauptgürtels, der am 10. September 1858 von Hermann Mayer Salomon Goldschmidt entdeckt wurde.
    - [en] 54 Alexandra

    [es] (54) Alexandra

    (54) Alexandra es un asteroide perteneciente al cinturón de asteroides descubierto por Hermann Mayer Salomon Goldschmidt el 10 de septiembre de 1858 desde París, Francia. Está nombrado en honor del naturalista y astrónomo alemán Alexander von Humboldt (1769-1859).[2]

    [ru] (54) Александра

    (54) Алекса́ндра (лат. Alexandra) — неправильной формы астероид главного пояса, который принадлежит к тёмному спектральному классу C. Он был открыт 10 сентября 1858 года немецким астрономом Германом Гольдшмидтом с помощью 4-дюймового телескопа, расположенного на шестом этаже его квартиры в Латинском квартале Парижа. Один из астероидов, который получил название не по имени одного из мифологических персонажей — назван в честь немецкого исследователя Александра фон Гумбольдта[2].


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