Asteroids with Satellites Database--Johnston's Archive

(93) Minerva, Aegis, and Gorgoneion

compiled by Wm. Robert Johnston
last updated 21 September 2014

--Orbital and physical data--

(See this page for definitions of quantities; source codes in brackets, see this link for full references; *A, *D, and *E indicate assumed, derived, and estimated values, respectively.)

dynamical type, primary: main belt asteroid


orbital data, primary (osculating elements) [JPL] :
semimajor axis a: 2.754124319 AU
orbital period P: 4.570708370 yr
(= 1669.4512320 d)
eccentricity e: 0.141224590
perihelion distance q: 2.36517424 AU
aphelion distance Q: 3.143074397 AU
inclination i: 8.5606727°
argument of perihelion ω: 274.841096°
ascending node Ω: 4.075600°
mean anomaly M: 89.251029°
perihelion passage TP: 2013 Apr 04.11044
Epoch: 2014 May 23
data arc: 1870-2013 (1304 obs.)
Earth MOID: 1.3678 AU
Jupiter Tisserand invariant TJ: 3.314


orbital data, Aegis:
binary dynamical type:L [M09a]
semimajor axis as: 623.5 ± 10 km [M13c]
separation/primary radius as/rp:8.8 [*D]
separation/Hill radius as/rH:0.021 [*D]
orbital period Ps: 2.406 ± 0.002 d [M13c]
eccentricity es: 0.000 ± 0.009 [M13c]
inclination is:89.0° ± 10.9° [M13c]
ascending node Ωs:126° ± 10° [M13c]
argument of pericenter ωs:82° ± 14.4° [M13c]
pericenter passage TP:2009 Aug 15.9± 0.1 [M13c]
normalized ang. mom. αL: 0.4 [M09a]


orbital data, Gorgoneion:
binary dynamical type:L [M09a]
semimajor axis as: 375 ± 16 km [M13c]
separation/primary radius as/rp:5.3 [*D]
separation/Hill radius as/rH:0.013 [*D]
orbital period Ps: 1.1147 ± 0.0006 d [M13c]
eccentricity es: 0.05 ± 0.04 [M13c]
inclination is:91.4° ± 24.1° [M13c]
ascending node Ωs:132.6° ± 23.6° [M13c]
argument of pericenter ωs:347.5° ± 27.7° [M13c]
pericenter passage TP:2009 Aug 15.8± 0.08 [M13c]
normalized ang. mom. αL: 0.4 [M09a]

other data, system (combined):
absolute mag. H: 7.8 [MPC]
7.7 ± 0.2 [M13c]
slope parameter G: (0.15) [*A]
effective diameter dE: 141.6 ± 4 km [T04c]
geometric albedo: 0.073 ± 0.004 [T04c]
color index U-B: 0.315 [JPL]
color index B-V: 0.685 [JPL]
taxonomic type: C (SMASSII) [JPL]
CU (Tholen) [JPL]
mass m: 3.35x1018 ± 5.4x1017 kg [M13c]
density ρ: 1.75 ± 0.3 g/cm3[M13c]
Hill radius rH: 29000 km [*D]

other data, primary:
diameter dp: 141.6 ± 4 km [T04c]
rotation period RPp: 5.981767 ± 0.000004 h [M13c]
amplitude in mag., rotational ΔM: ?
pole direction Β, λ: 21 ± 10° , 21 ± 10° [M13c]


other data, Aegis:
diameter ds: 3.6 ± 1.0 km [M13c]
diameter ratio ds/dp: 0.028 ± 0.014 [*D]
component mag. difference ΔM: 7.8 [*D]
rotation period RPs: ?


other data, Gorgoneion:
diameter ds: 3.2 ± 0.9 km [M13c]
diameter ratio ds/dp: 0.021 ± 0.007 [*D]
component mag. difference ΔM: 8.4 [*D]
rotation period RPs: ?

-- (93) Minerva, Aegis, and Gorgoneion --discovery and notes:

Primary discovered 1867 Aug 24 from Ann Arbor, Michigan, USA by J. C. Watson. Alternate designation(s): 1949 QN2, A902 DA. Permanent number assigned 1867.

Named 1867 for the mythological Roman goddess of wisdom.

Second component discovered 2009 Aug 16 by F. Marchis and B. Macomber using adaptive optics telescope observations from W. M. Keck II Telescope, Mauna Kea, Hawaii, USA. Announced 2009 Aug 31 [M09c]. Provisional designation S/2009 (93) 1. Permanent designation I Aegis, assigned 2013 Dec 17; named for the Roman mythological shield [MPC85917].

Third component discovered 2009 Aug 16 by F. Marchis and B. Macomber using adaptive optics telescope observations from W. M. Keck II Telescope, Mauna Kea, Hawaii, USA. Announced 2009 Aug 31 [M09c]. Provisional designation S/2009 (93) 2. Permanent designation II Gorgoneion, assigned 2013 Dec 17; named for the Roman mythological amulet [MPC85917].

Shape model published [M13c].

--Links, more technical:

--Links, less technical:

--Links to ADS abstracts:


© 2009, 2014 by Wm. Robert Johnston.
Last modified 21 September 2014.
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