76 Freia

76 Freia
A three-dimensional model of 76 Freia based on its light curve.
Discovery
Discovered by Heinrich d'Arrest
Discovery date October 21, 1862
Designations
MPC designation (76) Freia
Pronunciation /ˈfraɪ.ə/ FRY-ə
Named after
 Freyja
Outer main belt[1] (Cybele)
Orbital characteristics
Epoch December 31, 2006 (JD 2454100.5)
Aphelion 594.715 Gm (3.975 AU)
Perihelion 427.898 Gm (2.860 AU)
511.306 Gm (3.418 AU)
Eccentricity 0.163
2307.979 d (6.32 a)
16.00 km/s
299.268°
Inclination 2.116°
204.535°
254.070°
Physical characteristics
Dimensions 183.7±4 km[1]
Mass (1.97 ± 4.20) × 1018 kg[2]
Mean density
 0.79 ± 1.69[2] g/cm3
Equatorial surface gravity
 0.0513 m/s²
Equatorial escape velocity
 0.0971 km/s
9.968240±0.000009 h[3]
0.036 [4]
CP
7.90

    76 Freia (/ˈfraɪ.ə/ FRY-ə) is a very large main-belt asteroid. It orbits in the outer part of the asteroid belt and is classified as a Cybele asteroid. Its composition is very primitive and it is extremely dark in color. Freia was discovered by the astronomer Heinrich d'Arrest on October 21, 1862, in Copenhagen, Denmark. It was his first and only asteroid discovery. It is named after the goddess Freyja in Norse mythology.

    The sidereal orbital period of this asteroid is commensurable with that of Jupiter, which made it useful for ground-based mass estimates of the giant planet.[5] A shape model for the asteroid was published by Stephens and Warner (2008), based upon lightcurve data. This yielded a sidereal rotation period of 9.968240±0.000009 h. They found two possible solutions for the spin axis, with the preferred solution in ecliptic coordinates being (λ, β) = (139°±5°, 25°±5°).[3]

    References

    1. 1 2 "JPL Small-Body Database Browser: 76 Freia" (2008-03-04 last obs). Retrieved 2010-09-05.
    2. 1 2 Carry, B. (December 2012), "Density of asteroids", Planetary and Space Science, 73, pp. 98–118, arXiv:1203.4336, Bibcode:2012P&SS...73...98C, doi:10.1016/j.pss.2012.03.009. See Table 1.
    3. 1 2 Stephens, Robert D.; Warner, Brian D. (June 2008), "A Preliminary Shape and Spin Axis Model for 76 Freia", The Minor Planet Bulletin, 35 (2): 84−85, Bibcode:2008MPBu...35...84S.
    4. ↑ Asteroid Data Sets Archived 2010-01-17 at WebCite
    5. ↑ Klepczynski, W. J.; et al. (November 1971), "The Mass of Jupiter from the Motion of (76) Freia", Astronomical Journal, 76: 939, Bibcode:1971AJ.....76..939K, doi:10.1086/111204.


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