Back 128 نيميسيس (كويكب) ARZ 128 Nemesis AST (128) Немезіда Byelorussian (128) Nèmesi Catalan (128) Немезида CE (128) Nemesis German 128 Νέμεσις Greek 128 Nemezo Esperanto (128) Némesis Spanish 128 Nemesis Basque

128 Nemesis

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
163±5 km[6]
162.5±1.3 km[7]
184.2±5.2 km[8]
Flattening0.17[a]
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)[9]
38.9325 h (1.62219 d)[3]
0.067 (calculated)[6]
0.067±0.005[3]
Tholen = C[3]
SMASS = C[3]
7.70[3]

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.

  1. ^ a b Cite error: The named reference MPC-object was invoked but never defined (see the help page).
  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 Cite error: The named reference jpldata was invoked but never defined (see the help page).
  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 Cite error: The named reference Masiero-2014 was invoked but never defined (see the help page).
  8. ^ a b c Cite error: The named reference Carry2012 was invoked but never defined (see the help page).
  9. ^ a b Cite error: The named reference Scaltriti1979 was invoked but never defined (see the help page).
  10. ^ Cite error: The named reference DeMeo2009 was invoked but never defined (see the help page).
  11. ^ Cite error: The named reference jpl-search was invoked but never defined (see the help page).
  12. ^ Cite error: The named reference Pilcher2015 was invoked but never defined (see the help page).
  13. ^ Cite error: The named reference SBDB was invoked but never defined (see the help page).


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