185 Eunike

185 Eunike is a dark and very large main-belt asteroid. 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).

DiscoveredbyC. H. F. Peters, 1878

Discoverydate1 March 1878

MPCdesignation

(185) Eunike

Pronunciation/juːˈnaɪkiː/^[1]

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185 Eunike

Orbital diagram
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
Alternative designations	A878 EA
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 (sidereal)	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]
Synodic 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]

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This object is orbiting the Sun at a distance of 2.74 AU with an eccentricity of 0.129 and an orbital period of 4.53 years. Its orbital plane is inclined at an angle of 23.2° to the plane of the ecliptic. Using infrared measurements, the diameter has been measured at 160.464 km. It has a primitive carbonaceous composition.

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]

As of 17 September 2020, there have been thirteen observed occultations of stars by Eunike.^{[citation needed]}