20729 Opheltius

Last updated

20729 Opheltius
Discovery [1]
Discovered by C. W. Juels
Discovery site Fountain Hills Obs.
Discovery date15 December 1999
Designations
20729 Opheltius
Named after
Opheltius
1999 XS143
Jupiter trojan [1] [2]
Greek [3]  · background [4]
Orbital characteristics [2]
Epoch 23 March 2018 (JD 2458200.5)
Uncertainty parameter 0
Observation arc 65.26 yr (23,838 d)
Aphelion 5.5498 AU
Perihelion 4.8840 AU
5.2169 AU
Eccentricity 0.0638
11.92 yr (4,352 d)
252.20°
0° 4m 57.72s / day
Inclination 22.008°
306.91°
92.027°
Jupiter  MOID 0.1123 AU
TJupiter 2.8500
Physical characteristics
50.96±0.96  km [5]
5.72±0.02  h [6]
0.052±0.017 [5]
C (assumed) [7]
V–I = 1.000±0.060 [7]
10.3 [5]
10.4 [1] [2] [7]

    20729 Opheltius (provisional designation 1999 XS143) is a Jupiter trojan from the Greek camp, approximately 51 kilometers (32 miles) in diameter. It was discovered on 15 December 1999, by American astronomer Charles Juels at the Fountain Hills Observatory in Arizona. [1] The dark Jovian asteroid has a short rotation period of 5.72 hours and belongs to the 90 largest Jupiter trojans. [7]

    Contents

    Orbit and classification

    Opheltius is a dark Jovian asteroid orbiting in the leading Greek camp at Jupiter's L4 Lagrangian point, 60° ahead of the Gas Giant's orbit in a 1:1 resonance (see Trojans in astronomy). [3] It is also a non-family asteroid in the Jovian background population. [4]

    It orbits the Sun at a distance of 4.9–5.5  AU once every 11 years and 11 months (4,352 days; semi-major axis of 5.22 AU). Its orbit has an eccentricity of 0.06 and an inclination of 22° with respect to the ecliptic. [2]

    The body's observation arc begins with a precovery published by the Digitized Sky Survey and taken at the Palomar Observatory in February 1953, almost 47 years prior to its official discovery observation at Fountain Hills. [1]

    Numbering and naming

    This minor planet was numbered on 9 January 2001 ( M.P.C. 41908). [8] It was named in April 2025 after Opheltius, the name of two mythological figures; one an Achean killed by Hector, and the other a defender of Troy. [9]

    Physical characteristics

    Opheltius is an assumed carbonaceous C-type asteroid. It has a high V–I color index of 1.00 (see table below). [7]

    Rotation period

    In September 2008, a rotational lightcurve of Opheltius was obtained from photometric observations. Lightcurve analysis gave a rotation period of 5.72±0.02 hours with a brightness variation of 0.33 magnitude ( U=2 ). [6] [7]

    Observations by Stefano Mottola at the Calar Alto Observatory in October 2009 showed a divergent period of 7.631 hours with an amplitude of 0.20 magnitude ( U=2 ). [7] [10]

    Diameter and albedo

    According to the survey carried out by the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, Opheltius is 50.96 kilometers in diameter and its surface has an albedo of 0.052, [5] while the Collaborative Asteroid Lightcurve Link assumes a standard albedo for a carbonaceous asteroid of 0.057 and calculates a diameter of 46.30 kilometers based on an absolute magnitude of 10.4. [7] The object was neither observed by IRAS nor the Akari satellite.

    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 YoDRef
    624 Hektor 7.2225233230.99L46.920.9301907 list
    617 Patroclus 8.19140.362140.92140.85L5102.800.8301906 list
    911 Agamemnon 7.89131.038166.66185.30L46.590.9801919 list
    588 Achilles 8.67130.099135.47133.22L47.310.9401906 list
    3451 Mentor 8.4126.288116.30117.91L57.700.7701984 list
    3317 Paris 8.3118.790116.26120.45L57.090.9501984 list
    1867 Deiphobus 8.3118.220122.67131.31L558.660.9301971 list
    1172 Äneas 8.33118.020142.82148.66L58.710.9501930 list
    1437 Diomedes 8.3117.786164.31172.60L424.490.8101937 list
    1143 Odysseus 7.93114.624125.64130.81L410.110.8601930 list
    2241 Alcathous 8.64113.682114.63118.87L57.690.9401979 list
    659 Nestor 8.99112.320108.87107.06L415.980.7901908 list
    3793 Leonteus 8.7112.04686.2687.58L45.620.7801985 list
    3063 Makhaon 8.4111.655116.14114.34L48.640.8301983 list
    1583 Antilochus 8.6108.842101.62111.69L431.540.9501950 list
    884 Priamus 8.81101.09396.29119.99L56.860.9001917 list
    1208 Troilus 8.99100.477103.34111.36L556.170.7401931 list
    1173 Anchises 8.8999.549126.27120.49L511.600.7801930 list
    2207 Antenor 8.8997.65885.1191.32L57.970.9501977 list
    2363 Cebriones 9.1195.97681.8484.61L520.050.9101977 list
    4063 Euforbo 8.795.619102.46106.38L48.850.9501989 list
    2357 Phereclos 8.9494.62594.9098.45L514.390.9601981 list
    4709 Ennomos 8.591.43380.8580.03L512.280.6901988 list
    2797 Teucer 8.789.430111.14113.99L410.150.9201981 list
    2920 Automedon 8.888.574111.01113.11L410.210.9501981 list
    15436 Dexius 9.187.64685.7178.63L48.970.8701998 list
    3596 Meriones 9.287.38075.0973.28L412.960.8301985 list
    2893 Peiroos 9.2386.88487.4686.76L58.960.9501975 list
    4086 Podalirius 9.185.49586.8985.98L410.430.8701985 list
    4060 Deipylos 9.384.04379.2186.79L49.300.7601987 list
    1404 Ajax 9.383.99081.6996.34L429.380.9601936 list
    4348 Poulydamas 9.582.03270.0887.51L59.910.8401988 list
    5144 Achates 9.080.95891.9189.85L55.960.9201991 list
    4833 Meges 8.980.16587.3389.39L414.250.9401989 list
    2223 Sarpedon 9.4177.48094.63108.21L522.740.8801977 list
    4489 Dracius 9.076.59592.9395.02L412.580.9501988 list
    2260 Neoptolemus 9.3176.43571.6581.28L48.180.9501975 list
    5254 Ulysses 9.276.14778.3480.00L428.720.9701986 list
    3708 Socus 9.375.66179.5976.75L56.550.9801974 list
    2674 Pandarus 9.174.26798.10101.72L58.481.0001982 list
    3564 Talthybius 9.473.73068.9274.11L440.590.9001985 list
    4834 Thoas 9.172.33186.8296.21L418.190.9501989 list
    7641 Cteatus 9.471.83968.9775.28L427.770.9801986 list
    3540 Protesilaos 9.370.22576.8487.66L48.950.9401973 list
    11395 Iphinous 9.868.97764.7167.78L417.381998 list
    4035 Thestor 9.668.73368.2366.99L413.470.9701986 list
    5264 Telephus 9.468.47273.2681.38L49.530.9701991 list
    1868 Thersites 9.568.16370.0878.89L410.480.9601960 list
    9799 Thronium 9.668.03364.8772.42L421.520.9101996 list
    4068 Menestheus 9.567.62562.3768.46L414.400.9501973 list
    23135 Pheidas 9.966.23058.2968.50L48.690.8602000 list
    2456 Palamedes 9.365.91691.6699.60L47.240.9201966 list
    3709 Polypoites 9.165.29799.0985.23L410.041.0001985 list
    1749 Telamon 9.564.89881.0669.14L416.980.9701949 list
    3548 Eurybates 9.663.88572.1468.40L48.710.7301973 list
    4543 Phoinix 9.763.83662.7969.54L438.871.2001989 list
    12444 Prothoon 9.863.83564.3162.41L515.821996 list
    4836 Medon 9.563.27767.7378.70L49.820.9201989 list
    16070 Charops 9.763.19164.1368.98L520.240.9601999 list
    15440 Eioneus 9.662.51966.4871.88L421.430.9701998 list
    4715 Medesicaste 9.762.09763.9165.93L58.810.8501989 list
    34746 Thoon 9.861.68460.5163.63L519.630.9502001 list
    38050 Bias 9.861.60361.0450.44L418.850.9901998 list
    5130 Ilioneus 9.760.71159.4052.49L514.770.9601989 list
    5027 Androgeos 9.659.78657.86n.a.L411.380.9101988 list
    6090 Aulis 9.459.56874.5381.92L418.480.9801989 list
    5648 Axius 9.759.29563.91n.a.L537.560.9001990 list
    7119 Hiera 9.759.15076.4077.29L44000.9501989 list
    4805 Asteropaios 10.057.64753.1643.44L512.371990 list
    16974 Iphthime 9.857.34155.4357.15L478.90.9601998 list
    4867 Polites 9.857.25158.2964.29L511.241.0101989 list
    2895 Memnon 10.056.70655.67n.a.L57.500.7101981 list
    4708 Polydoros 9.954.96455.67n.a.L57.520.9601988 list
    21601 Aias 10.054.90955.6756.08L412.650.9701998 list
    12929 Periboea 9.954.07761.0455.34L59.270.8801999 list
    17492 Hippasos 10.053.97555.67n.a.L517.751991 list
    5652 Amphimachus 10.153.92153.1652.48L48.371.0501992 list
    2759 Idomeneus 9.953.67661.0152.55L432.380.9101980 list
    5258 Rhoeo 10.253.27550.77n.a.L419.851.0101989 list
    12126 Chersidamas 10.153.202n.a.n.a.L5n.a. ?1999 list
    15502 Hypeirochus 10.053.10055.6750.86L515.130.8751999 list
    4754 Panthoos 10.053.02553.1556.96L527.681977 list
    4832 Palinurus 10.052.05853.16n.a.L55.321.0001988 list
    5126 Achaemenides 10.551.92244.2248.57L453.021989 list
    3240 Laocoon 10.251.69550.77n.a.L511.310.8801978 list
    4902 Thessandrus 9.851.26361.0471.79L47380.9601989 list
    11552 Boucolion 10.151.13653.1653.91L532.441993 list
    20729 Opheltius 10.450.96146.30n.a.L45.721.0001999 list
    6545 Leitus 10.150.95153.16n.a.L416.260.9101986 list
    4792 Lykaon 10.150.87053.16n.a.L540.090.9601988 list
    21900 Orus 10.050.81055.6753.87L413.450.9501999 list
    1873 Agenor 10.150.79953.7654.38L520.601971 list
    5028 Halaesus 10.250.77050.77n.a.L424.940.9001988 list
    2146 Stentor 9.950.75558.29n.a.L416.401976 list
    4722 Agelaos 10.050.37853.1659.47L518.440.9101977 list
    5284 Orsilocus 10.150.15953.16n.a.L410.310.9701989 list
    11509 Thersilochos 10.149.96053.1656.23L517.371990 list
    5285 Krethon 10.149.60658.5352.61L412.041.0901989 list
    4791 Iphidamas 10.149.52857.8559.96L59.701.0301988 list
    9023 Mnesthus 10.149.15150.7760.80L530.661988 list
    5283 Pyrrhus 9.748.35664.5869.93L47.320.9501989 list
    4946 Askalaphus 10.248.20952.7166.10L422.730.9401988 list
    22149 Cinyras 10.248.19050.7750.37L47.841.0902000 list
    32496 Deïopites 10.248.01750.7751.63L523.340.9502000 list
    5120 Bitias 10.247.98750.77n.a.L515.210.7801988 list
    12714 Alkimos 10.147.81961.0454.62L428.481991 list
    7352 Hypsenor 9.947.73155.67 47.07L56480.8501994 list
    1870 Glaukos 10.647.64942.23n.a.L55.991971 list
    4138 Kalchas 10.146.46253.1661.04L429.20.8101973 list
    23958 Theronice 10.246.00150.7747.91L45620.9901998 list
    4828 Misenus 10.445.95446.30 43.22L512.870.9201988 list
    4057 Demophon 10.145.68353.16n.a.L429.821.0601985 list
    4501 Eurypylos 10.445.52446.30n.a.L46.051989 list
    4007 Euryalos 10.345.51548.4853.89L46.391973 list
    5259 Epeigeus 10.344.74142.5944.42L418.421989 list
    30705 Idaios 10.444.54646.30n.a.L515.741977 list
    16560 Daitor 10.743.86151.4243.38L51991 list
    15977 Pyraechmes 10.443.53046.3051.53L52500.9061998 list
    7543 Prylis 10.642.89342.23n.a.L417.801973 list
    4827 Dares 10.542.77044.22n.a.L519.001988 list
    1647 Menelaus 10.542.71644.22n.a.L417.740.8661957 list
    (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 "20729 (1999 XS143)". Minor Planet Center. Retrieved 20 June 2018.
    2. 1 2 3 4 "JPL Small-Body Database Browser: 20729 (1999 XS143)" (2018-05-23 last obs.). Jet Propulsion Laboratory . Retrieved 20 June 2018.
    3. 1 2 "List of Jupiter Trojans". Minor Planet Center. 1 June 2018. Retrieved 20 June 2018.
    4. 1 2 "Asteroid (20729) 1999 XS143 – Proper Elements". AstDyS-2, Asteroids – Dynamic Site. Retrieved 20 June 2018.
    5. 1 2 3 4 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)
    6. 1 2 Melita, M. D.; Duffard, R.; Williams, I. P.; Jones, D. C.; Licandro, J.; Ortiz, J. L. (June 2010). "Lightcurves of 6 Jupiter Trojan asteroids". Planetary and Space Science. 58 (7–8): 1035–1039. Bibcode:2010P&SS...58.1035M. doi:10.1016/j.pss.2010.03.009.
    7. 1 2 3 4 5 6 7 8 "LCDB Data for (20729)". Asteroid Lightcurve Database (LCDB). Retrieved 20 June 2018.
    8. "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 20 June 2018.
    9. "WGSBN Bulletin 5, #5" (PDF). WGSBN Bulletin. 5 (5). International Astronomical Union. 7 April 2025. Retrieved 7 April 2025.
    10. Mottola, Stefano; Di Martino, Mario; Erikson, Anders; Gonano-Beurer, Maria; Carbognani, Albino; Carsenty, Uri; et al. (May 2011). "Rotational Properties of Jupiter Trojans. I. Light Curves of 80 Objects". The Astronomical Journal. 141 (5): 32. Bibcode:2011AJ....141..170M. doi: 10.1088/0004-6256/141/5/170 .