128 Nemesis
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For other uses, see Nemesis (disambiguation).
| Discovery[1] | |
|---|---|
| Discovered by | James Craig Watson |
| Discovery date | November 25, 1872 |
| Designations | |
| Pronunciation | /ˈnɛmɨsɪs/ |
| Named after | Nemesis |
| Alternative names | |
| Minor planet category | Main belt,[1]nemesis family |
| Orbital characteristics | |
| Epoch December 31, 2006 (JD 2454100.5) | |
| Aphelion | 463.605 Gm (3.099 AU) |
| Perihelion | 359.010 Gm (2.400 AU) |
| Semi-major axis | 411.307 Gm (2.749 AU) |
| Eccentricity | 0.127 |
| Orbital period | 1665.175 d (4.56 a) |
| Average orbital speed | 17.89 km/s |
| Mean anomaly | 181.168° |
| Inclination | 6.254° |
| Longitude of ascending node | 76.457° |
| Argument of perihelion | 302.407° |
| Physical characteristics | |
| Dimensions |
188.16 km[1] 184.19 ± 5.19[2] km |
| Mass | (5.97 ± 2.56) × 1018[2] kg |
| Mean density | 1.82 ± 0.79[2] g/cm3 |
| Equatorial surface gravity | 0.0526 m/s² |
| Escape velocity | 0.0995 km/s |
| Rotation period | 39 hr[1] |
| Albedo | 0.05[1] |
| Temperature | ~168 K |
| Spectral type | C[1] |
| Apparent magnitude | 10.46 to 13.58 |
| Absolute magnitude (H) | 7.49[1] |
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128 Nemesis is a large 188 km main-belt asteroid, of carbonaceous composition. It rotates rather slowly, taking about one and half Earth days (39 hours)[1] to complete one revolution.[3] Nemesis is the largest member of the Nemesian asteroid family bearing its name. It was discovered by J. C. Watson on November 25, 1872,[1] and named after Nemesis, the goddess of retribution in Greek mythology. Nemesis is also the name of a hypothetical companion star of the Sun.
It is categorized as a C-type asteroid,[4] indicating a primitive carbonaceous composition. Based on IRAS data Nemesis is about 188 km in diameter and is around the 33rd largest main-belt asteroid.[5]
References
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 "JPL Small-Body Database Browser: 128 Nemesis". Jet Propulsion Laboratory. 2011-06-13 last obs (arc=138 years). Retrieved 2011-12-06.
- ↑ 2.0 2.1 2.2 Carry, B. (December 2012), "Density of asteroids", Planetary and Space Science 73: 98–118, arXiv:1203.4336, Bibcode:2012P&SS...73...98C, doi:10.1016/j.pss.2012.03.009. See Table 1.
- ↑ Scaltriti, F.; Zappala, V.; Schober, H. J. (January 1979), "The rotations of 128 Nemesis and 393 Lampetia - The longest known periods to date", Icarus 37: 133–141, Bibcode:1979Icar...37..133S, doi:10.1016/0019-1035(79)90121-0.
- ↑ DeMeo, Francesca E. et al. (July 2009), "An extension of the Bus asteroid taxonomy into the near-infrared", Icarus 202 (1): 160–180, Bibcode:2009Icar..202..160D, doi:10.1016/j.icarus.2009.02.005, retrieved 2013-04-08. See appendix A.
- ↑ "JPL Small-Body Database Search Engine: asteroids and orbital class (IMB or MBA or OMB) and diameter > 188.1 (km)". JPL's Solar System Dynamics Group. Retrieved 2012-04-17.
External links
- Orbital simulation from JPL (Java) / Ephemeris
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