128 Nemesis

128 Nemesis
Discovery[1]
Discovered by James Craig Watson
Discovery date 25 November 1872
Designations
MPC designation (128) Nemesis
Pronunciation /ˈnɛmɪsɪs/
Named after
 Nemesis
main-belt [1][2] · Nemesis
Orbital characteristics [2]
Epoch 23 March 2018 (JD 2458200.5)
Uncertainty parameter 0
Observation arc 144.93 yr (52,934 d)
Aphelion 3.0996 AU
Perihelion 2.3998 AU
2.7497 AU
Eccentricity 0.1272
4.56 yr (1,665 d)
345.49°
0° 12m 58.32s / day
Inclination 6.2453°
76.243°
303.82°
Physical characteristics
Mean diameter
 162.515±1.296 km[3]
184.19 ± 5.19 km[4]
Mass (5.97±2.56)×1018 kg[4]
Mean density
 1.82 ± 0.79 g/cm3[4]
77.81 h (3.242 d)[2]
0.0504±0.002[2]
Tholen = C [2]
SMASS = C [2]
7.49[2]

    128 Nemesis is a large 180 km main-belt asteroid, of carbonaceous composition. It rotates rather slowly, taking about 78 hours to complete one rotation.[2][5] Nemesis is the largest member of the Nemesian asteroid family bearing its name. It was discovered by J. C. Watson on 25 November 1872,[2] and named after Nemesis, the goddess of retribution in Greek mythology. Nemesis was also the name of a hypothetical companion star of the Sun, which does not exist.

    It is categorized as a C-type asteroid,[6] 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.[7] The 77.81‑hour[8] rotation period is the second longest for an asteroid more than 150 km in diameter.[9]

    References

    1. 1 2 "128 Nemesis". Minor Planet Center. Retrieved 14 September 2018.
    2. 1 2 3 4 5 6 7 8 9 "JPL Small-Body Database Browser: 128 Nemesis" (2017-10-31 last obs.). Jet Propulsion Laboratory. Retrieved 14 September 2018.
    3. ↑ Masiero, Joseph R.; Grav, T.; Mainzer, A. K.; Nugent, C. R.; Bauer, J. M.; Stevenson, R.; et al. (August 2014). "Main-belt Asteroids with WISE/NEOWISE: Near-infrared Albedos" (PDF). The Astrophysical Journal. 791 (2): 11. arXiv:1406.6645. Bibcode:2014ApJ...791..121M. doi:10.1088/0004-637X/791/2/121. Retrieved 14 September 2018.
    4. 1 2 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.
    5. ↑ 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, pp. 133–141, Bibcode:1979Icar...37..133S, doi:10.1016/0019-1035(79)90121-0.
    6. ↑ DeMeo, Francesca E.; et al. (July 2009), "An extension of the Bus asteroid taxonomy into the near-infrared" (PDF), Icarus, 202 (1), pp. 160–180, Bibcode:2009Icar..202..160D, doi:10.1016/j.icarus.2009.02.005, archived from the original (PDF) on 2014-03-17, retrieved 2013-04-08. See appendix A.
    7. ↑ "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.
    8. ↑ Pilcher, Frederick (July 2015), "New Photometric Observations of 128 Nemisis, 249 Ilse, and 279 Thule", The Minor Planet Bulletin, 42 (3): 190−192, Bibcode:2015MPBu...42..190P.
    9. ↑ "JPL Small-Body Database Search Engine: diameter > 150 (km) and rot_per > 24 (h)". JPL Solar System Dynamics. Retrieved 2015-06-06.

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