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	/ˈfreɪ.ə/[1]
Named after	Freyja
Minor planet category	Outer main belt[2] (Cybele)
Adjectives	Freian
Orbital characteristics
	Epoch December 31, 2006 (JD 2454100.5)
Aphelion	594.715 Gm (3.975 AU)
Perihelion	427.898 Gm (2.860 AU)
Semi-major axis	511.306 Gm (3.418 AU)
Eccentricity	0.163
Orbital period	2307.979 d (6.32 a)
Average orbital speed	16.00 km/s
Mean anomaly	299.268°
Inclination	2.116°
Longitude of ascending node	204.535°
Argument of perihelion	254.070°
Physical characteristics
Dimensions	183.7±4 km[2]
Mass	(1.97 ± 4.20) × 1018 kg[3]
Mean density	0.79 ± 1.69[3] g/cm3
Equatorial surface gravity	0.0513 m/s²
Equatorial escape velocity	0.0971 km/s
Rotation period	9.968240±0.000009 h[4]
Geometric albedo	0.036 [5]
Spectral type	CP
Absolute magnitude (H)	7.90

Freia (minor planet designation: 76 Freia) 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.[6] 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°).[4]

References

"Freya". Lexico UK Dictionary. Oxford University Press.
"JPL Small-Body Database Browser: 76 Freia" (2008-03-04 last obs). Retrieved 5 September 2010.
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.
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.
Asteroid Data Sets Archived 2009-12-17 at the Wayback Machine
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.

External links

76 Freia at AstDyS-2, Asteroids—Dynamic Site
- Ephemeris · Observation prediction · Orbital info · Proper elements · Observational info
76 Freia at the JPL Small-Body Database
- Close approach · Discovery · Ephemeris · Orbit diagram · Orbital elements · Physical parameters

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[1] "Freya". Lexico UK Dictionary. Oxford University Press.

[jpldata-2] "JPL Small-Body Database Browser: 76 Freia" (2008-03-04 last obs). Retrieved 5 September 2010.

[Carry2012-3] 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.

[Stephens2008-4] 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.

[5] Asteroid Data Sets Archived 2009-12-17 at the Wayback Machine

[Klepczynski1971-6] 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.