Asteroids with Satellites Database--Johnston's Archive

(87) Sylvia, Romulus, and Remus

compiled by Wm. Robert Johnston
last updated 27 May 2014
under construction--testing upgrades!

--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, outer


orbital data, primary (osculating elements) [JPL] :
semimajor axis a: 3.481808398 AU
orbital period P: 6.497039467 yr (= 2373.043665 d)
eccentricity e: 0.091145156
perihelion distance q: 3.16445843 AU
aphelion distance Q: 3.799158367 AU
inclination i: 10.8768036°
argument of perihelion ω: 263.685494°
ascending node Ω: 73.083782°
mean anomaly M: 179.424861°
perihelion passage TP: 2011 Feb 25.2693
Epoch: 2014 May 23
data arc: 1894-2013 (2348 obs.)
Earth MOID: 2.1794 AU
Jupiter Tisserand invariant TJ: 3.094


orbital data, Romulus:
binary dynamical type:L [P07f]
semimajor axis as: 1357 ± 4 km [F12b]
separation/primary radius as/rp:9.5 [*D]
separation/Hill radius as/rH:0.021 [*D]
orbital period Ps: 3.654 ± 0.024 d [F12b]
eccentricity es: 0.006 ± 0.005 [F12b]
inclination is:1.7°± 1.0 [*M05a]
normalized ang. mom. αL: 0.65 [P07f]


orbital data, Remus:
binary dynamical type:L [*VO]
semimajor axis as: 706.5 ± 2.5 km [F12b]
separation/primary radius as/rp:4.9 [*D]
separation/Hill radius as/rH:0.011 [*D]
orbital period Ps: 1.373 ± 0.01 d [F12b]
eccentricity es: 0.027 ± 0.013 [F12b]
inclination is:2.0°± 1.0 [*M05a]
normalized ang. mom. αL: 0.65 [*VO]

other data, system (combined):
absolute mag. H: 6.94 [MPC]
slope parameter G: 0.15 [*A]
effective diameter dE: 286 ± 11 km [M05a]
geometric albedo: 0.036 ± 0.008 [M11b]
color index U-B: 0.251 [T95a]
color index B-V: 0.71 [JPL]
taxonomic type: X (SMASSII) [JPL]
P (Tholen) [JPL]
mass m: 1.48x1019 ± 1.5x1017 kg [F12b]
density ρ: 1.2 ± 0.1 g/cm3 [M05a]
Hill radius rH: 64000 km [*D]

other data, primary:
diameter dp: 286 ± 11 km [M05a]
dimensions :384x264x232km []
axial ratios a/b, b/c:1.46;1.14 [*M05a]
rotation period RPp: 5.183640 ± 0.000005 h [D95a]
amplitude in mag., rotational ΔM: ?
pole direction : 86±6° ; 45±10° ; [D95a]


other data, Romulus:
diameter ds: 10.8 ± 5.6 km [F12b]
diameter ratio ds/dp: 0.038 ± 0.02 [*D]
component mag. difference ΔM: 6.24 ± 0.20 [I7590]
rotation period RPs: ?


other data, Remus:
diameter ds: 10.6 ± 1.6 km [F12b]
diameter ratio ds/dp: 0.037 ± 0.006 [*D]
component mag. difference ΔM: 7.2 [*D]
rotation period RPs: ?

-- (87) Sylvia, Romulus, and Remus --discovery and notes:

Primary discovered 1866 May 16 from Madras, India by N. R. Pogson. Alternate designation(s): A909 GA. Permanent number assigned 1866 May 28.

Named 1866 May 28 for the Roman mythological character.

Second component discovered 2001 Feb 18 by M. E. Brown and J. L. Margot using AOT observations from W. M. Keck II Telescope, Mauna Kea, Hawaii, USA. Announced 2001 Feb 23 [I7588]. Provisional designation S/2001 (87) 1. Permanent designation I Romulus, assigned 2005 Aug 11; named for the Roman mythological character [I8582].

Third component discovered 2004 Aug 09 by F. Marchis, P. Descamps, D. Hestroffer, and J. Berthier using AOT observations from Very Large Telescope, ESO, Cerro Paranal, Chile. Announced 2005 Aug 11 [M05a]. Provisional designation S/2004 (87) 1. Permanent designation II Remus, assigned 2005 Aug 11; named for the Roman mythological character [I8582].

--Links, more technical:

--Links, less technical:

--Links to ADS abstracts:


© 2001-2007, 2014 by Wm. Robert Johnston.
Last modified 27 May 2014.
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