185 Eunike

185 Eunike
Discovery
Discovered by	C. H. F. Peters, 1878
Discovery date	1 March 1878
Designations
MPC designation	(185) Eunike
Pronunciation	/juːˈnaɪkiː/[1]
Named after	Εὐνίκη Eynīkē
Minor planet category	Main belt
Adjectives	Eunikean /juːnɪˈkiːən/
Orbital characteristics[2]
	Epoch 31 July 2016 (JD 2457600.5)
	Uncertainty parameter 0
Observation arc	131.77 yr (48128 d)
Aphelion	3.0924 AU (462.62 Gm)
Perihelion	2.3843 AU (356.69 Gm)
Semi-major axis	2.7383 AU (409.64 Gm)
Eccentricity	0.12930
Orbital period	4.53 yr (1655.1 d)
Mean anomaly	327.48°
Mean motion	0° 13m 3.036s / day
Inclination	23.238°
Longitude of ascending node	153.84°
Argument of perihelion	224.01°
Earth MOID	1.41759 AU (212.068 Gm)
Jupiter MOID	2.40697 AU (360.078 Gm)
TJupiter	3.222
Physical characteristics
Dimensions	157.51±2.6 km[2]; 160.61 ± 5.00 km[3]
Mass	(3.56 ± 2.61) × 1018 kg[3]
Mean density	1.64 ± 1.21 g/cm3[3]
Rotation period	21.797 h (0.9082 d)[2]; 21.812 ± 0.001 hours[4]
Geometric albedo	0.0638±0.002
Spectral type	C
Absolute magnitude (H)	7.62,[2] 7.45 ± 0.01[4]

Eunike (minor planet designation: 185 Eunike) is a dark and very large main-belt asteroid, with an approximate diameter of 157 kilometres. It has a primitive carbonaceous composition.

It was discovered by C. H. F. Peters on March 1, 1878, in Clinton, New York and named after Eunike, a Nereid in Greek mythology whose name means 'happy victory'. The name was chosen to celebrate the Treaty of San Stefano (1878).

Based upon photometric observations made between 2010 and 2014, this asteroid has a rotation period of 21.812 ± 0.001 hours and a brightness variation of 0.08 ± 0.01 in magnitude. At opposition, the absolute magnitude was measured at 7.45 ± 0.01. It displays a hemispheric albedo dichotomy similar to that on 4 Vesta.[4]

There have been three observed occultations of stars by Eunike.

References

Noah Webster (1884) A Practical Dictionary of the English Language
"185 Eunike". JPL Small-Body Database. NASA/Jet Propulsion Laboratory. Retrieved 12 May 2016.
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.
Pilcher, Frederick; et al. (October 2014), "A Comprehensive Photometric Investigation of 185 Eunike", of the Minor Planets Section of the Association of Lunar and Planetary Observers, 41 (4): 244–250, Bibcode:2014MPBu...41..244P.

External links

185 Eunike at AstDyS-2, Asteroids—Dynamic Site
- Ephemeris · Observation prediction · Orbital info · Proper elements · Observational info
185 Eunike at the JPL Small-Body Database
- Close approach · Discovery · Ephemeris · Orbit diagram · Orbital elements · Physical parameters

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[1] Noah Webster (1884) A Practical Dictionary of the English Language

[jpldata-2] "185 Eunike". JPL Small-Body Database. NASA/Jet Propulsion Laboratory. Retrieved 12 May 2016.

[Carry2012-3] 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.

[bmps41_4_244-4] Pilcher, Frederick; et al. (October 2014), "A Comprehensive Photometric Investigation of 185 Eunike", of the Minor Planets Section of the Association of Lunar and Planetary Observers, 41 (4): 244–250, Bibcode:2014MPBu...41..244P.