15 Eunomia
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|
| Discovery A (http://cfa-www.harvard.edu/iau/lists/NumberedMPs.html) | |
|---|---|
| Discoverer | Annibale de Gasparis |
| Discovery date | July 29, 1851 |
| Alternate designations | B (http://cfa-www.harvard.edu/iau/MPDes.html) |
| Category | Main belt, Eunomia family |
| Orbital elements C (http://asteroid.lowell.edu/) Epoch October 22, 2004 (JD 2453300.5) | |
| Eccentricity (e) | 0.186 |
| Semi-major axis (a) | 395.872 Gm (2.646 AU) |
| Perihelion (q) | 322.290 Gm (2.154 AU) |
| Aphelion (Q) | 469.453 Gm (3.138 AU) |
| Orbital period (P) | 1572.323 d (4.30 a) |
| Mean orbital speed | 18.15 km/s |
| Inclination (i) | 11.732° |
| Longitude of the ascending node (Ω) | 293.399° |
| Argument of perihelion (ω) | 97.577° |
| Mean anomaly (M) | 148.829° |
| Physical characteristics | |
| Dimensions | 255.3 km |
| Mass | 8.4×1018 kg |
| Density | 0.96 g/cm³ 1 (http://www.psi.edu/pds/archive/density.html) |
| Surface gravity | 0.0343 m/s² |
| Escape velocity | 0.0935 km/s |
| Rotation period | 0.2535 d (6.083 h) 2 (http://www.astrosurf.com/aude-old/map_files/AstVarMAP01-2003.htm) |
| Spectral class | S-type asteroid |
| Absolute magnitude | 5.28 |
| Albedo | 0.209 3 (http://dorothy.as.arizona.edu/DSN/IRAS/index_iras.html) |
| Mean surface temperature | ~168 K |
15 Eunomia (ew-noh'-mee-a) is the 12th largest Main belt asteroid. It is also the largest member of the Eunomia family of asteroids. Like other true members of the family, it is composed of silicates and nickel-iron. It is light in colour.
It was discovered by A. de Gasparis on July 29, 1851 and named after Eunomia, one of the Horae (Hours), a personification of order and law in Greek mythology.
Eunomia has rather variable lightcurve indicating an elongated object. This led to a suggestion that Eunomia may be a binary object. However, it was refuted later. [1] (http://www.johnstonsarchive.net/astro/asteroidmoonsq.html)
Eunomia has been observed occulting stars three times.
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