2148 Epeios
Discovery[1]
Discovered byR. M. West
Discovery siteLa Silla Obs.
Discovery date24 October 1976
Designations
(2148) Epeios
Pronunciation/ɪˈpɒs, -əs/[2]
Named after
Epeius[1]
(Greek mythology)
1976 UW
Jupiter trojan[1][3]
Greek[4] · background[5]
Orbital characteristics[3]
Epoch 23 March 2018 (JD 2458200.5)
Uncertainty parameter 0
Observation arc40.69 yr (14,862 d)
Aphelion5.5118 AU
Perihelion4.9188 AU
5.2153 AU
Eccentricity0.0569
11.91 yr (4,350 d)
243.53°
0° 4m 58.08s / day
Inclination9.1481°
176.56°
231.58°
Jupiter MOID0.0308 AU
TJupiter2.9710
Physical characteristics
Mean diameter
37.98±0.32 km[6]
0.064±0.003[6]
10.8[1][3]

    2148 Epeios /ɪˈpɒs/ is a mid-sized Jupiter trojan from the Greek camp, approximately 38 kilometers (24 miles) in diameter. It was discovered on 24 October 1976, by Danish astronomer Richard Martin West at ESO's La Silla Observatory in northern Chile.[1] The dark Jovian asteroid is the principal body of the proposed Epeios family and was named after Epeius from Greek mythology.[1]

    Orbit and classification

    Epeios is a Jupiter trojan in a 1:1 orbital resonance with Jupiter. It is located in the leading Greek camp at the Gas Giant's L4 Lagrangian point, 60° ahead on its orbit (see Trojans in astronomy).[4] It orbits the Sun at a distance of 4.9–5.5 AU once every 11 years and 11 months (4,350 days; semi-major axis of 5.22 AU). Its orbit has an eccentricity of 0.06 and an inclination of 9° with respect to the ecliptic.[3] The body's observation arc begins with its official discovery observation at La Silla in October 1976.[1]

    Epeios family

    Fernando Roig and Ricardo Gil-Hutton identified Epeios as the principal body of a small Jovian asteroid family, using the hierarchical clustering method (HCM), which looks for groupings of neighboring asteroids based on the smallest distances between them in the proper orbital element space. According to the astronomers, the Epeios family belongs to the larger Menelaus clan, an aggregation of Jupiter trojans which is composed of several families, similar to the Flora family in the inner asteroid belt.[7]:9,10

    However this family is not included in David Nesvorný's HCM-analysis from 2014.[8][9] Instead, Epeios is listed as a non-family asteroid of the Jovian background population on the Asteroids Dynamic Site (AstDyS) which based on another analysis by Milani and Knežević.[5]

    Naming

    This minor planet was named from Greek mythology after the Greek warrior Epeius, leader of the contingent from Phocis during the Trojan War. Epeius also built the wooden Trojan Horse. He then chose the other 29 soldiers who would accompany him inside.[1] The official naming citation was published by the Minor Planet Center on 1 July 1979 (M.P.C. 4788).[10]

    Physical characteristics

    Rotation period

    As of 2018, no rotational lightcurve of Epeios has been obtained from photometric observations. The body's rotation period, pole and shape remain unknown.[3][9]

    Diameter and albedo

    According to the survey carried out by the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, Epeios measures 37.98 kilometers in diameter and its surface has an albedo of 0.064.[6]

    100+ largest Jupiter trojans
    Largest Jupiter Trojans by survey(A)
    (mean-diameter in kilometers; YoD: Year of Discovery)
    Designation H WISE IRAS Akari Ln RP V–I YoD Ref
    624 Hektor7.2225233230.99L46.920.9301907list
    617 Patroclus8.19140.362140.92140.85L5102.800.8301906list
    911 Agamemnon7.89131.038166.66185.30L46.590.9801919list
    588 Achilles8.67130.099135.47133.22L47.310.9401906list
    3451 Mentor8.4126.288116.30117.91L57.700.7701984list
    3317 Paris8.3118.790116.26120.45L57.090.9501984list
    1867 Deiphobus8.3118.220122.67131.31L558.660.9301971list
    1172 Äneas8.33118.020142.82148.66L58.710.9501930list
    1437 Diomedes8.3117.786164.31172.60L424.490.8101937list
    1143 Odysseus7.93114.624125.64130.81L410.110.8601930list
    2241 Alcathous8.64113.682114.63118.87L57.690.9401979list
    659 Nestor8.99112.320108.87107.06L415.980.7901908list
    3793 Leonteus8.7112.04686.2687.58L45.620.7801985list
    3063 Makhaon8.4111.655116.14114.34L48.640.8301983list
    1583 Antilochus8.6108.842101.62111.69L431.540.9501950list
    884 Priamus8.81101.09396.29119.99L56.860.9001917list
    1208 Troilus8.99100.477103.34111.36L556.170.7401931list
    1173 Anchises8.8999.549126.27120.49L511.600.7801930list
    2207 Antenor8.8997.65885.1191.32L57.970.9501977list
    2363 Cebriones9.1195.97681.8484.61L520.050.9101977list
    4063 Euforbo8.795.619102.46106.38L48.850.9501989list
    2357 Phereclos8.9494.62594.9098.45L514.390.9601981list
    4709 Ennomos8.591.43380.8580.03L512.280.6901988list
    2797 Teucer8.789.430111.14113.99L410.150.9201981list
    2920 Automedon8.888.574111.01113.11L410.210.9501981list
    15436 Dexius9.187.64685.7178.63L48.970.8701998list
    3596 Meriones9.287.38075.0973.28L412.960.8301985list
    2893 Peiroos9.2386.88487.4686.76L58.960.9501975list
    4086 Podalirius9.185.49586.8985.98L410.430.8701985list
    4060 Deipylos9.384.04379.2186.79L49.300.7601987list
    1404 Ajax9.383.99081.6996.34L429.380.9601936list
    4348 Poulydamas9.582.03270.0887.51L59.910.8401988list
    5144 Achates9.080.95891.9189.85L55.960.9201991list
    4833 Meges8.980.16587.3389.39L414.250.9401989list
    2223 Sarpedon9.4177.48094.63108.21L522.740.8801977list
    4489 Dracius9.076.59592.9395.02L412.580.9501988list
    2260 Neoptolemus9.3176.43571.6581.28L48.180.9501975list
    5254 Ulysses9.276.14778.3480.00L428.720.9701986list
    3708 Socus9.375.66179.5976.75L56.550.9801974list
    2674 Pandarus9.174.26798.10101.72L58.481.0001982list
    3564 Talthybius9.473.73068.9274.11L440.590.9001985list
    4834 Thoas9.172.33186.8296.21L418.190.9501989list
    7641 Cteatus9.471.83968.9775.28L427.770.9801986list
    3540 Protesilaos9.370.22576.8487.66L48.950.9401973list
    11395 Iphinous9.868.97764.7167.78L417.381998list
    4035 Thestor9.668.73368.2366.99L413.470.9701986list
    5264 Telephus9.468.47273.2681.38L49.530.9701991list
    1868 Thersites9.568.16370.0878.89L410.480.9601960list
    9799 Thronium9.668.03364.8772.42L421.520.9101996list
    4068 Menestheus9.567.62562.3768.46L414.400.9501973list
    23135 Pheidas9.966.23058.2968.50L48.690.8602000list
    2456 Palamedes9.365.91691.6699.60L47.240.9201966list
    3709 Polypoites9.165.29799.0985.23L410.041.0001985list
    1749 Telamon9.564.89881.0669.14L416.980.9701949list
    3548 Eurybates9.663.88572.1468.40L48.710.7301973list
    4543 Phoinix9.763.83662.7969.54L438.871.2001989list
    12444 Prothoon9.863.83564.3162.41L515.821996list
    4836 Medon9.563.27767.7378.70L49.820.9201989list
    16070 Charops9.763.19164.1368.98L520.240.9601999list
    15440 Eioneus9.662.51966.4871.88L421.430.9701998list
    4715 Medesicaste9.762.09763.9165.93L58.810.8501989list
    34746 Thoon9.861.68460.5163.63L519.630.9502001list
    38050 Bias9.861.60361.0450.44L418.850.9901998list
    5130 Ilioneus9.760.71159.4052.49L514.770.9601989list
    5027 Androgeos9.659.78657.86n.a.L411.380.9101988list
    6090 Aulis9.459.56874.5381.92L418.480.9801989list
    5648 Axius9.759.29563.91n.a.L537.560.9001990list
    7119 Hiera9.759.15076.4077.29L44000.9501989list
    4805 Asteropaios10.057.64753.1643.44L512.371990list
    16974 Iphthime9.857.34155.4357.15L478.90.9601998list
    4867 Polites9.857.25158.2964.29L511.241.0101989list
    2895 Memnon10.056.70655.67n.a.L57.500.7101981list
    4708 Polydoros9.954.96455.67n.a.L57.520.9601988list
    (21601) 1998 XO8910.054.90955.6756.08L412.650.9701998list
    12929 Periboea9.954.07761.0455.34L59.270.8801999list
    17492 Hippasos10.053.97555.67n.a.L517.751991list
    5652 Amphimachus10.153.92153.1652.48L48.371.0501992list
    2759 Idomeneus9.953.67661.0152.55L432.380.9101980list
    5258 Rhoeo10.253.27550.77n.a.L419.851.0101989list
    (12126) 1999 RM1110.153.202n.a.n.a.L5n.a. ?1999list
    (15502) 1999 NV2710.053.10055.6750.86L515.130.8751999list
    4754 Panthoos10.053.02553.1556.96L527.681977list
    4832 Palinurus10.052.05853.16n.a.L55.321.0001988list
    5126 Achaemenides10.551.92244.2248.57L453.021989list
    3240 Laocoon10.251.69550.77n.a.L511.310.8801978list
    4902 Thessandrus9.851.26361.0471.79L47380.9601989list
    11552 Boucolion10.151.13653.1653.91L532.441993list
    (20729) 1999 XS14310.450.96146.30n.a.L45.721.0001999list
    6545 Leitus10.150.95153.16n.a.L416.260.9101986list
    4792 Lykaon10.150.87053.16n.a.L540.090.9601988list
    21900 Orus10.050.81055.6753.87L413.450.9501999list
    1873 Agenor10.150.79953.7654.38L520.601971list
    5028 Halaesus10.250.77050.77n.a.L424.940.9001988list
    2146 Stentor9.950.75558.29n.a.L416.401976list
    4722 Agelaos10.050.37853.1659.47L518.440.9101977list
    5284 Orsilocus10.150.15953.16n.a.L410.310.9701989list
    11509 Thersilochos10.149.96053.1656.23L517.371990list
    5285 Krethon10.149.60658.5352.61L412.041.0901989list
    4791 Iphidamas10.149.52857.8559.96L59.701.0301988list
    9023 Mnesthus10.149.15150.7760.80L530.661988list
    5283 Pyrrhus9.748.35664.5869.93L47.320.9501989list
    4946 Askalaphus10.248.20952.7166.10L422.730.9401988list
    (22149) 2000 WD4910.248.19050.7750.37L47.841.0902000list
    (32496) 2000 WX18210.248.01750.7751.63L523.340.9502000list
    5120 Bitias10.247.98750.77n.a.L515.210.7801988list
    12714 Alkimos10.147.81961.0454.62L428.481991list
    7352 Hypsenor9.947.73155.67 47.07L56480.8501994list
    1870 Glaukos10.647.64942.23n.a.L55.991971list
    4138 Kalchas10.146.46253.1661.04L429.20.8101973list
    (23958) 1998 VD3010.246.00150.7747.91L45620.9901998list
    4828 Misenus10.445.95446.30 43.22L512.870.9201988list
    4057 Demophon10.145.68353.16n.a.L429.821.0601985list
    4501 Eurypylos10.445.52446.30n.a.L46.051989list
    4007 Euryalos10.345.51548.4853.89L46.391973list
    5259 Epeigeus10.344.74142.5944.42L418.421989list
    30705 Idaios10.444.54646.30n.a.L515.741977list
    16560 Daitor10.743.86151.4243.38L51991list
    (15977) 1998 MA1110.443.53046.3051.53L52500.9061998list
    7543 Prylis10.642.89342.23n.a.L417.801973list
    4827 Dares10.542.77044.22n.a.L519.001988list
    1647 Menelaus10.542.71644.22n.a.L417.740.8661957list
    (A) Used sources: WISE/NEOWISE catalog (NEOWISE_DIAM_V1 PDS, Grav, 2012); IRAS data (SIMPS v.6 catalog); and Akari catalog (Usui, 2011); RP: rotation period and V–I (color index) taken from the LCDB

    Note: missing data was completed with figures from the JPL SBDB (query) and from the LCDB (query form) for the WISE/NEOWISE and SIMPS catalogs, respectively. These figures are given in italics. Also, listing is incomplete above #100.

    References

    1. 1 2 3 4 5 6 7 8 "2148 Epeios (1976 UW)". Minor Planet Center. Retrieved 20 June 2018.
    2. 'Epeus' in Noah Webster (1884) A Practical Dictionary of the English Language
    3. 1 2 3 4 5 "JPL Small-Body Database Browser: 2148 Epeios (1976 UW)" (2017-07-03 last obs.). Jet Propulsion Laboratory. Retrieved 20 June 2018.
    4. 1 2 "List of Jupiter Trojans". Minor Planet Center. 1 June 2018. Retrieved 20 June 2018.
    5. 1 2 "Asteroid (2148) Epeios – Proper Elements". AstDyS-2, Asteroids – Dynamic Site. Retrieved 20 June 2018.
    6. 1 2 3 Grav, T.; Mainzer, A. K.; Bauer, J. M.; Masiero, J. R.; Nugent, C. R. (November 2012). "WISE/NEOWISE Observations of the Jovian Trojan Population: Taxonomy". The Astrophysical Journal. 759 (1): 10. arXiv:1209.1549. Bibcode:2012ApJ...759...49G. doi:10.1088/0004-637X/759/1/49. S2CID 119101711. (online catalog)
    7. Roig, F.; Ribeiro, A. O.; Gil-Hutton, R. (June 2008). "Taxonomy of asteroid families among the Jupiter Trojans: comparison between spectroscopic data and the Sloan Digital Sky Survey colors". Astronomy and Astrophysics. 483 (3): 911–931. arXiv:0712.0046. Bibcode:2008A&A...483..911R. doi:10.1051/0004-6361:20079177. S2CID 118361725.
    8. Nesvorný, D.; Broz, M.; Carruba, V. (December 2014). "Identification and Dynamical Properties of Asteroid Families". Asteroids IV. pp. 297–321. arXiv:1502.01628. Bibcode:2015aste.book..297N. doi:10.2458/azu_uapress_9780816532131-ch016. ISBN 9780816532131. S2CID 119280014.
    9. 1 2 "Asteroid 2148 Epeios". Small Bodies Data Ferret. Retrieved 20 June 2018.
    10. Schmadel, Lutz D. (2009). "Appendix – Publication Dates of the MPCs". Dictionary of Minor Planet Names – Addendum to Fifth Edition (2006–2008). Springer Berlin Heidelberg. p. 221. Bibcode:2009dmpn.book.....S. doi:10.1007/978-3-642-01965-4. ISBN 978-3-642-01964-7.
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