Astronomy:76 Freia
.png) A three-dimensional model of 76 Freia based on its light curve. | |
| Discovery | |
|---|---|
| Discovered by | Heinrich d'Arrest |
| Discovery date | October 21, 1862 |
| Designations | |
| (76) Freia | |
| Pronunciation | /ˈfreɪ.ə/[2] |
| Named after | Freyja |
| Minor planet category | Outer main belt[1] (Cybele) |
| Adjectives | Freian |
| Orbital characteristics | |
| Epoch December 31, 2006 (JD 2454100.5) | |
| |{{{apsis}}}|helion}} | 594.715 Gm (3.975 AU) |
| |{{{apsis}}}|helion}} | 427.898 Gm (2.860 AU) |
| 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° |
| 254.070° | |
| Physical characteristics | |
| Dimensions | 183.7±4 km[1] |
| 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] |
| 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.[6] 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.[7] 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
- ↑ 1.0 1.1 "JPL Small-Body Database Browser: 76 Freia". https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=76.
- ↑ "Freya". Freya. Oxford University Press. http://www.lexico.com/definition/Freya.
- ↑ 3.0 3.1 Carry, B. (December 2012), "Density of asteroids", Planetary and Space Science 73 (1): 98–118, doi:10.1016/j.pss.2012.03.009, Bibcode: 2012P&SS...73...98C. See Table 1.
- ↑ 4.0 4.1 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
- ↑ De Prá, M. N. et al. (September 2018), "PRIMASS visits Hilda and Cybele groups", Icarus 311: 35–51, doi:10.1016/j.icarus.2017.11.012, Bibcode: 2018Icar..311...35D.
- ↑ Klepczynski, W. J. et al. (November 1971), "The Mass of Jupiter from the Motion of (76) Freia", Astronomical Journal 76: 939, doi:10.1086/111204, Bibcode: 1971AJ.....76..939K.
External links
- 76 Freia at AstDyS-2, Asteroids—Dynamic Site
- 76 Freia at the JPL Small-Body Database
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