128 Nemesis

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128 Nemesis
128 Nemesis (orbit).gif
Discovery[1]
Discovered by James Craig Watson
Discovery date 25 November 1872
Designations
Pronunciation /ˈnɛmsɪs/
Named after
Nemesis
 
Main belt,[1]
Orbital characteristics[1]
Epoch 31 July 2016 (JD 2457600.5)
Uncertainty parameter 0
Observation arc 143.39 yr (52373 d)
Aphelion 3.09824 AU (463.490 Gm)
Perihelion 2.40068 AU (359.137 Gm)
2.74946 AU (411.313 Gm)
Eccentricity 0.12685
4.56 yr (1665.2 d)
17.89 km/s
215.699°
0° 12m 58.277s / day
Inclination 6.24500°
76.2475°
303.860°
Earth MOID 1.40918 AU (210.810 Gm)
Jupiter MOID 2.36425 AU (353.687 Gm)
Jupiter Tisserand parameter 3.326
Physical characteristics
Dimensions 188.16±4.0 km[1]
184.19 ± 5.19 km[2]
Mass (5.97 ± 2.56) × 1018 kg[2]
Mean density
1.82 ± 0.79 g/cm3[2]
Equatorial surface gravity
0.0526 m/s²
Equatorial escape velocity
0.0995 km/s
77.81 h (3.242 d)[1]
0.0504±0.002[1]
Temperature ~168 K
C[1]
Nemesis Family
10.46 to 13.58
7.49[1]

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 was also the name of a hypothetical companion star of the Sun, which does not exist.

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] The 39‑hour rotation period is the second longest for an asteroid more than 150 km in diameter.[6]

References[edit]

  1. ^ a b c d e f g h i j "JPL Small-Body Database Browser: 128 Nemesis" (2011-06-13 last obs (arc=138 years)). Jet Propulsion Laboratory. Retrieved 12 May 2016. 
  2. ^ a b c Carry, B. (December 2012), "Density of asteroids", Planetary and Space Science, 73, pp. 98–118, arXiv:1203.4336free to read, Bibcode:2012P&SS...73...98C, doi:10.1016/j.pss.2012.03.009.  See Table 1.
  3. ^ 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. 
  4. ^ 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, retrieved 2013-04-08.  See appendix A.
  5. ^ "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. 
  6. ^ "JPL Small-Body Database Search Engine: diameter > 150 (km) and rot_per > 24 (h)". JPL Solar System Dynamics. Retrieved 2015-06-06. 

External links[edit]