128 Nemesis
Discovery[1]
Discovered byJames Craig Watson
Discovery date25 November 1872
Designations
(128) Nemesis
Pronunciation/ˈnɛmɪsɪs/[2]
Named after
Nemesis
A872 WA; 1952 HW1
main-belt[1][3] · Nemesis
AdjectivesNemesian /nəˈmiːʒ(i)ən/[4][5]
Orbital characteristics[3]
Epoch 23 March 2018 (JD 2458200.5)
Uncertainty parameter 0
Observation arc144.93 yr (52,934 d)
Aphelion3.10 AU (463.69 Gm)
Perihelion2.40 AU (359.00 Gm)
2.75 AU (411.35 Gm)
Eccentricity0.1272
4.56 years (1,665 d)
345.49°
0° 12m 58.32s / day
Inclination6.2453°
76.243°
303.82°
Physical characteristics
Dimensionsc/a = 0.83±0.04[6]
Mean diameter
163±5 km[6]
162.5±1.3 km[7]
184.2±5.2 km[8]
Mass(3.4±1.7)×1018 kg[6]
(6.0±2.6)×1018 kg[8]
Mean density
1.5±0.8 g/cm3[6]
1.82±0.79 g/cm3[8]
77.81 h (3.242 d)[3]
0.067 (calculated)[6]
0.0504±0.002[3]
Tholen = C[3]
SMASS = C[3]
7.49[3]

Nemesis (minor planet designation: 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.[3][9] Nemesis is the largest member of the Nemesian asteroid family bearing its name. It was discovered by J. C. Watson on 25 November 1872,[3] and named after Nemesis, the goddess of retribution in Greek mythology.

Nemesis' orbit

This object is orbiting the Sun with a period of 4.56 years and an eccentricity (ovalness) of 0.13. The orbital plane is inclined by 6.2° to the plane of the ecliptic. It is categorized as a C-type asteroid,[10] 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,[11] while WISE measurements yield a size of ~163 km.[7] The 77.81‑hour[12] rotation period is the second longest for an asteroid more than 150 km in diameter.[13]

Between 2005 and 2021, 128 Nemesis has been observed to occult eight stars.

References

  1. ^ a b "128 Nemesis". Minor Planet Center. Retrieved 14 September 2018.
  2. ^ "Nemesis". Oxford English Dictionary (Online ed.). Oxford University Press. (Subscription or participating institution membership required.)
  3. ^ a b c d e f g h i "JPL Small-Body Database Browser: 128 Nemesis" (2017-10-31 last obs.). Jet Propulsion Laboratory. Retrieved 14 September 2018.
  4. ^ Hornum (1993) Nemesis, the Roman state and the games
  5. ^ Peery (1963) Studies in the Renaissance, vol. 10
  6. ^ a b c d e P. Vernazza et al. (2021) VLT/SPHERE imaging survey of the largest main-belt asteroids: Final results and synthesis. Astronomy & Astrophysics 54, A56
  7. ^ a b 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". The Astrophysical Journal. 791 (2): 11. arXiv:1406.6645. Bibcode:2014ApJ...791..121M. doi:10.1088/0004-637X/791/2/121. S2CID 119293330.
  8. ^ a b c Carry, B. (December 2012), "Density of asteroids", Planetary and Space Science, 73 (1): 98–118, arXiv:1203.4336, Bibcode:2012P&SS...73...98C, doi:10.1016/j.pss.2012.03.009, S2CID 119226456. See Table 1.
  9. ^ 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 (1): 133–141, Bibcode:1979Icar...37..133S, doi:10.1016/0019-1035(79)90121-0.
  10. ^ DeMeo, Francesca E.; et al. (July 2009), "An extension of the Bus asteroid taxonomy into the near-infrared" (PDF), Icarus, 202 (1): 160–180, Bibcode:2009Icar..202..160D, doi:10.1016/j.icarus.2009.02.005, archived from the original (PDF) on 17 March 2014, retrieved 8 April 2013. See appendix A.
  11. ^ "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 17 April 2012.
  12. ^ Pilcher, Frederick (July 2015), "New Photometric Observations of 128 Nemisis [sic], 249 Ilse, and 279 Thule", The Minor Planet Bulletin, 42 (3): 190−192, Bibcode:2015MPBu...42..190P.
  13. ^ "JPL Small-Body Database Search Engine: diameter > 150 (km) and rot_per > 24 (h)". JPL Solar System Dynamics. Retrieved 6 June 2015.

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