1173 Anchises

1173 Anchises /æŋˈksz/ is an unusually elongated Jupiter Trojan from the Trojan camp, approximately 124 kilometers (77 miles) in diameter. It was discovered on 17 October 1930, by German astronomer Karl Reinmuth at the Heidelberg Observatory in southwest Germany, and was the 9th such body to be discovered.[1][8]:2 The primitive P-type asteroid belongs to the largest Jupiter trojans, has an unusually smooth surface texture, the lowest spectral slope of all members of the Trojan camp, and a rotation period of 11.6 hours.[5] It was named after Anchises from Greek mythology.[3]

1173 Anchises
Shape model of Anchises from its lightcurve
Discovery[1]
Discovered byK. Reinmuth
Discovery siteHeidelberg Obs.
Discovery date17 October 1930
Designations
(1173) Anchises
Pronunciation/æŋˈksz/[2]
Named after
Anchises (Greek mythology)[3]
1930 UB
Jupiter trojan[1][4][5]
Trojan[6][7] · background[7]
Orbital characteristics[4]
Epoch 23 March 2018 (JD 2458200.5)
Uncertainty parameter 0
Observation arc87.60 yr (31,997 d)
Aphelion6.0232 AU
Perihelion4.5678 AU
5.2955 AU
Eccentricity0.1374
12.19 yr (4,451 d)
184.44°
0° 4m 51.24s / day
Inclination6.9202°
283.91°
40.496°
Jupiter MOID0.4727 AU
TJupiter2.9670
Physical characteristics
Dimensions170 km × 121 km × 121 km[8]
Mean diameter
99.55±0.85 km[9]
120.49±2.91 km[10]
126.27±10.7 km[11]
136±18 km[8]
11.595±0.002 h[12][lower-alpha 1]
11.596±0.005 h[13][lower-alpha 2]
11.60 h[14]
0.0308±0.006[11]
0.035±0.002[10]
0.050±0.009[9]
P (Tholen)[4][5][15]
D (Barucci)[15]
U–B = 0.266±080[4]
B–V = 0.770±0.050[16]
V–R = 0.450±0.030[16]
V–I = 0.950±0.026[5]
8.89[4][5][9][10][11]
9.14±0.31[17]
9.35[14]

    Orbit and classification

    Anchises is a primitive Jovian asteroid orbiting in the trailing Trojan camp at Jupiter's L5 Lagrangian point, 60° behind its orbit in a 1:1 resonance (see Trojans in astronomy). It is also a non-family asteroid of the Jovian background population.[7][15]

    It orbits the Sun at a distance of 4.6–6.0 AU once every 12 years and 2 months (4,451 days; semi-major axis of 5.3 AU). Its orbit has an eccentricity of 0.14 and an inclination of 7° with respect to the ecliptic.[4] Up to the year 2200, its closest approach to any major planet will be on 3 February 2120, when it will still be 2.669 AU (399,300,000 km; 248,100,000 mi) from Jupiter.[18] The body's observation arc begins at Heidelberg with its official discovery observation in October 1930.[1]

    Naming

    This minor planet was named after Anchises from Greek mythology. He is the father of the Trojan hero Aeneas after whom 1172 Äneas was named. The official naming citation was mentioned in The Names of the Minor Planets by Paul Herget in 1955 (H 109).[3]

    Physical characteristics

    In the Tholen classification, Anchises is a primitive P-type asteroid, a common spectral type among the Jupiter trojans.[4][5] It has the lowest spectral slope (i.e. flattest spectral response curve, thus most neutral color) among all members of the Trojan camp.[19] In the Barucci taxonomy, it has been characterized as a carbonaceous C-type asteroid (C0).[15]

    Rotation period

    In Summer 1986, the first photometric observations of Anchises were taken with the 0.9-meter telescope at the Cerro Tololo Observatory in Chile. Lightcurve analysis gave a well defined rotation period of 11.60 hours with a notably wide brightness variation of 0.57 magnitude (U=3).[14]

    Between January 2016, and December 2017, three more rotational lightcurves were obtained by American photometrist Robert Stephens at the Center for Solar System Studies in California. They gave a concurring period of 11.595,[lower-alpha 1] 11.596[lower-alpha 2] and 11.599 hours[lower-alpha 3] with an amplitude between 0.34 and 0.73 magnitude (U=3/3-/3?).[12][13] A high brightness amplitude is indicative for a non-spherical, elongated shape (see below).

    Diameter and albedo

    According to the surveys carried out by the Infrared Astronomical Satellite IRAS, the Japanese Akari satellite, the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, and astronomers revisiting the data from these three space-based telescopes, Anchises measures between 99.55 and 136 kilometers in diameter and its surface has an albedo between 0.0308 and 0.050.[8][9][10][11] The Collaborative Asteroid Lightcurve Link adopts the results obtained by IRAS, that is an albedo of 0.0308 and a diameter of 126.27 kilometers based on an absolute magnitude of 8.89.[5]

    This makes it the 7th largest Jupiter trojan only according to IRAS (126 km), and would be at least 6th should the size indeed prove to be 136 km or more, while it is much smaller and a few places further down the list according to the NEOWISE survey catalog (<100 km). One of the reasons for the large discrepancies in diameter estimates is possibly related to the results being derived from single-epoch observations of the asteroid, which is known for its large brightness variations (see above).[8]

    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) 1998 VU309.187.64685.7178.63L48.970.8701998list
    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) 1988 AK9.076.59592.9395.02L412.580.9501988list
    2260 Neoptolemus9.3176.43571.6581.28L48.180.9501975list
    5254 Ulysses9.276.14778.3480.00L428.720.9701986list
    (3708) 1974 FV19.375.66179.5976.75L56.550.9801974list
    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) 1986 TT69.471.83968.9775.28L427.770.9801986list
    3540 Protesilaos9.370.22576.8487.66L48.950.9401973list
    (11395) 1998 XN779.868.97764.7167.78L417.381998list
    (4035) 1986 WD9.668.73368.2366.99L413.470.9701986list
    5264 Telephus9.468.47273.2681.38L49.530.9701991list
    1868 Thersites9.568.16370.0878.89L410.480.9601960list
    (9799) 1996 RJ9.668.03364.8772.42L421.520.9101996list
    4068 Menestheus9.567.62562.3768.46L414.400.9501973list
    (23135) 2000 AN1469.966.23058.2968.50L48.690.8602000list
    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) 1999 RB1019.763.19164.1368.98L520.240.9601999list
    (15440) 1998 WX49.662.51966.4871.88L421.430.9701998list
    (4715) 1989 TS19.762.09763.9165.93L58.810.8501989list
    (34746) 2001 QE919.861.68460.5163.63L519.630.9502001list
    (38050) 1998 VR389.861.60361.0450.44L418.850.9901998list
    5130 Ilioneus9.760.71159.4052.49L514.770.9601989list
    5027 Androgeos9.659.78657.86n.a.L411.380.9101988list
    (6090) 1989 DJ9.459.56874.5381.92L418.480.9801989list
    (5648) 1990 VU19.759.29563.91n.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) 1999 TZ19.954.07761.0455.34L59.270.8801999list
    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) 1989 AU110.253.27550.77n.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) 1986 TR610.150.95153.16n.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) 1994 CO9.947.73155.67 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.

    Shape and surface

    In 2012, an international collaboration revisited the WISE, IRAS and Akari observational data. As already suggested by the body's high brightness amplitude, the astronomers found that Anchises is significantly elongated, with best-fit dimensions of 170 km × 121 km × 121 km, which corresponds to a mean diameter of 136+18
    −11
    kilometers.[8] Due to a small phase coefficient and a lack of any noticeable opposition effect, astronomers at Cerro Tololo concluded that this Jupiter trojan asteroid possesses an unusually smooth surface texture – far less rough than the great majority of asteroids.[14] In case the surface of Anchises consist of bare rock, with high thermal inertia, the body's true diameter could be significantly greater than the estimated 136 kilometers, the study concludes.[8]

    Notes

    1. Lightcurve plot of (1173) Anchises by Robert Stephens (Feb 2016). Rotation period 11.595±0.002 hours with a brightness amplitude of 0.61±0.02 mag. Quality code of 3. Summary figures at the Center for Solar System Studies (CS3) website and at the LCDB
    2. Lightcurve plot of (1173) Anchises by Robert Stephens (Dec 2016). Rotation period 11.596±0.005 hours with a brightness amplitude of 0.73±0.04 mag. Quality code of 3-. Summary figures at the Center for Solar System Studies (CS3) website and at the LCDB
    3. Lightcurve plot of (1173) Anchises by Robert Stephens (2017). Rotation period 11.599±0.001 hours with a brightness amplitude of 0.34±0.02 mag. Quality code of 3. Summary figures at the Center for Solar System Studies (CS3) website and at the LCDB

    References

    1. "1173 Anchises (1930 UB)". Minor Planet Center. Retrieved 12 June 2018.
    2. Noah Webster (1884) A Practical Dictionary of the English Language
    3. Schmadel, Lutz D. (2007). "(1173) Anchises". Dictionary of Minor Planet Names – (1173) Anchises. Springer Berlin Heidelberg. p. 99. doi:10.1007/978-3-540-29925-7_1174. ISBN 978-3-540-00238-3.
    4. "JPL Small-Body Database Browser: 1173 Anchises (1930 UB)" (2018-05-25 last obs.). Jet Propulsion Laboratory. Retrieved 12 June 2018.
    5. "LCDB Data for (1173) Anchises". Asteroid Lightcurve Database (LCDB). Retrieved 12 June 2018.
    6. "List of Jupiter Trojans". Minor Planet Center. 30 May 2018. Retrieved 12 June 2018.
    7. "Asteroid (1173) Anchises – Proper elements". AstDyS-2, Asteroids – Dynamic Site. Retrieved 5 June 2018.
    8. Horner, J.; Müller, T. G.; Lykawka, P. S. (July 2012). "(1173) Anchises – thermophysical and dynamical studies of a dynamically unstable Jovian Trojan". Monthly Notices of the Royal Astronomical Society. 423 (3): 2587–2596. arXiv:1204.1388. Bibcode:2012MNRAS.423.2587H. doi:10.1111/j.1365-2966.2012.21067.x.
    9. 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. (online catalog)
    10. Usui, Fumihiko; Kuroda, Daisuke; Müller, Thomas G.; Hasegawa, Sunao; Ishiguro, Masateru; Ootsubo, Takafumi; et al. (October 2011). "Asteroid Catalog Using Akari: AKARI/IRC Mid-Infrared Asteroid Survey". Publications of the Astronomical Society of Japan. 63 (5): 1117–1138. Bibcode:2011PASJ...63.1117U. doi:10.1093/pasj/63.5.1117. Retrieved 15 June 2018. (online, AcuA catalog p. 153)
    11. Tedesco, E. F.; Noah, P. V.; Noah, M.; Price, S. D. (October 2004). "IRAS Minor Planet Survey V6.0". NASA Planetary Data System – IRAS-A-FPA-3-RDR-IMPS-V6.0: IRAS-A-FPA-3-RDR-IMPS-V6.0. Bibcode:2004PDSS...12.....T. Retrieved 15 June 2018.
    12. Stephens, Robert D.; Coley, Daniel R.; French, Linda M. (July 2016). "A Report from the L5 Trojan Camp - Lightcurves of Jovian Trojan Asteroids from the Center for Solar System Studies". The Minor Planet Bulletin. 43 (3): 265–270. Bibcode:2016MPBu...43..265S. ISSN 1052-8091. Retrieved 3 March 2018.
    13. Stephens, Robert D. (April 2017). "Lightcurve Analysis of Trojan Asteroids at the Center for Solar System Studies 2016 October - December". The Minor Planet Bulletin. 44 (2): 123–125. Bibcode:2017MPBu...44..123S. ISSN 1052-8091. Retrieved 3 March 2018.
    14. French, L. M. (November 1987). "Rotation properties of four L5 Trojan asteroids from CCD photometry". Icarus. 72 (2): 325–341.MIT–supportedresearch. Bibcode:1987Icar...72..325F. doi:10.1016/0019-1035(87)90178-3. ISSN 0019-1035. Retrieved 3 March 2018.
    15. "Asteroid 1173 Anchises". Small Bodies Data Ferret. Retrieved 12 June 2018.
    16. Chatelain, Joseph P.; Henry, Todd J.; French, Linda M.; Winters, Jennifer G.; Trilling, David E. (June 2016). "Photometric colors of the brightest members of the Jupiter L5 Trojan cloud". Icarus. 271: 158–169. Bibcode:2016Icar..271..158C. doi:10.1016/j.icarus.2016.01.026. Retrieved 12 June 2018.
    17. Veres, Peter; Jedicke, Robert; Fitzsimmons, Alan; Denneau, Larry; Granvik, Mikael; Bolin, Bryce; et al. (November 2015). "Absolute magnitudes and slope parameters for 250,000 asteroids observed by Pan-STARRS PS1 - Preliminary results". Icarus. 261: 34–47. arXiv:1506.00762. Bibcode:2015Icar..261...34V. doi:10.1016/j.icarus.2015.08.007.
    18. Horizons output. "Observer Table for Asteroid 1173 Anchises (1930 UB)". Retrieved 4 April 2012. (Observer Location:@Jupiter)
    19. Fornasier, S.; Dotto, E.; Hainaut, O.; Marzari, F.; Boehnhardt, H.; De Luise, F.; et al. (October 2007). "Visible spectroscopic and photometric survey of Jupiter Trojans: Final results on dynamical families". Icarus. 190 (2): 622–642. arXiv:0704.0350. Bibcode:2007Icar..190..622F. doi:10.1016/j.icarus.2007.03.033.

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