1208 Troilus

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1208 Troilus
Discovery [1]
Discovered by K. Reinmuth
Discovery site Heidelberg Obs.
Discovery date 31 December 1931
Designations
MPC designation (1208) Troilus
Pronunciation /ˈtrɔɪləs/ · TROY-ləs
Named after
Troilus (Greek mythology)[2]
1931 YA · 1965 WK
Jupiter trojan[1][3][4]
Trojan[5][6] · background[6]
Orbital characteristics[3]
Epoch 23 March 2018 (JD 2458200.5)
Uncertainty parameter 0
Observation arc 86.40 yr (31,557 d)
Aphelion 5.7305 AU
Perihelion 4.7712 AU
5.2509 AU
Eccentricity 0.0913
12.03 yr (4,395 d)
189.17°
0° 4m 54.84s / day
Inclination 33.542°
48.546°
296.06°
Jupiter MOID 0.001 AU
TJupiter 2.6590
Physical characteristics
Mean diameter
100.48±1.10 km[7]
103.31 km (derived)[4]
103.34±3.9 km[8]
111.36±2.36 km[9]
24 h[10]
56.17±0.07 h[11]
63.8±0.5 h[12]
0.037±0.002[9]
0.0397 (derived)[4]
0.041±0.006[7]
0.0419±0.003[8]
FCU (Tholen)[3][4]
C0 (Barucci)
U–B = 0.314±093[3]
B–V = 0.750±0.050[13]
V–R = 0.380±0.030[13]
V–I = 0.740±0.020[4]
8.99[1][3][8][9]
9.05[4][10]
9.08[7][14]

1208 Troilus (/ˈtrɔɪləs/ TROY-ləs ), provisional designation 1931 YA, is a large and notably inclined Jupiter trojan from the Trojan camp, approximately 103 kilometers (64 miles) in diameter. It was discovered on 31 December 1931, by German astronomer Karl Reinmuth at the Heidelberg Observatory in southern Germany,[1] the unusual F-type asteroid belongs to the largest Jupiter trojans and has a long rotation period of 56.2 hours.[4] It was named after the Trojan prince Troilus, who was killed by Achilles.[2]

Orbit and classification[edit]

Troilus is a dark Jovian asteroid orbiting in the trailering Trojan camp at Jupiter's L5 Lagrangian point, 60° behind the Gas Giant's orbit in a 1:1 resonance (see Trojans in astronomy). It is also a non-family asteroid of the Jovian background population.[6][15]

It orbits the Sun at a distance of 4.8–5.7 AU once every 12 years (4,395 days; semi-major axis of 5.25 AU). Its orbit has an eccentricity of 0.09 and a high inclination of 34° with respect to the ecliptic.[3] The body's observation arc begins with its official discovery observation at Heidelberg in December 1931.[1]

Physical characteristics[edit]

In the Tholen classification, Troilus has an ambiguous and unusual spectrum, closest to that of an F-type and somewhat similar to a common C-type asteroid (FCU).[3][4] It has also been characterized as a carbonaceous C-type in the Barucci taxonomy (C0-type).[15]

Rotation period[edit]

In April 2007, a rotational lightcurve of Troilus was obtained from photometric observations by Lawrence Molnar at the Calvin-Rehoboth Robotic Observatory (G98) in New Mexico. Lightcurve analysis gave a rotation period of 56.17±0.07 hours with a brightness variation of 0.20±0.02 magnitude (U=2).[4][11] While not being a slow rotator, Troilus has a significantly longer period than most asteroids, and one of longest of all larger Jupiter trojans.

The period also supersedes previous observations made by Linda French with the 0.9-meter SMARTS telescope at Cerro Tololo in the 1980s and by Federico Manzini at the Sozzago Astronomical Station (A12), which gave a period of 24 and 63.8 hours, respectively (U=2/1).[10][12]

Diameter and albedo[edit]

According to the surveys carried out by the Infrared Astronomical Satellite IRAS, the Japanese Akari satellite and the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, Troilus measures between 100.48 and 111.36 kilometers in diameter and its surface has an albedo between 0.037 and 0.0419.[7][8][9] The Collaborative Asteroid Lightcurve Link derives an albedo of 0.0397 and a diameter of 103.31 kilometers based on an absolute magnitude of 9.05.[4]

List of largest Jupiter Trojans above 50 km
#
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8
9
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56
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58
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61
 
Largest Jupiter Trojans by survey(A)
(mean-diameter in kilometers; YoD: Year of Discovery)
Designation WISE IRAS Akari Ln RP V–I YoD Ref
624 Hektor 225 233 230.99 L4 6.92 0.930 1907 list
617 Patroclus 140.362 140.92 140.85 L5 102.80 0.830 1906 list
911 Agamemnon 131.038 166.66 185.30 L4 6.59 0.980 1919 list
588 Achilles 130.099 135.47 133.22 L4 7.31 0.940 1906 list
3451 Mentor 126.288 116.30 117.91 L5 7.70 0.770 1984 list
3317 Paris 118.790 116.26 120.45 L5 7.09 0.950 1984 list
1867 Deiphobus 118.220 122.67 131.31 L5 58.66 0.930 1971 list
1172 Äneas 118.020 142.82 148.66 L5 8.71 0.950 1930 list
1437 Diomedes 117.786 164.31 172.60 L4 24.49 0.810 1937 list
1143 Odysseus 114.624 125.64 130.81 L4 10.11 0.860 1930 list
2241 Alcathous 113.682 114.63 118.87 L5 7.69 0.940 1979 list
659 Nestor 112.320 108.87 107.06 L4 15.98 0.790 1908 list
3793 Leonteus 112.046 86.26 87.58 L4 5.62 0.780 1985 list
3063 Makhaon 111.655 116.14 114.34 L4 8.64 0.830 1983 list
1583 Antilochus 108.842 101.62 111.69 L4 31.54 0.950 1950 list
884 Priamus 101.093 96.29 119.99 L5 6.86 0.900 1917 list
1208 Troilus 100.477 103.34 111.36 L5 56.17 0.740 1931 list
1173 Anchises 99.549 126.27 120.49 L5 11.60 0.780 1930 list
2207 Antenor 97.658 85.11 91.32 L5 7.97 0.950 1977 list
2363 Cebriones 95.976 81.84 84.61 L5 20.05 0.910 1977 list
4063 Euforbo 95.619 102.46 106.38 L4 8.85 0.950 1989 list
2357 Phereclos 94.625 94.90 98.45 L5 14.39 0.960 1981 list
4709 Ennomos 91.433 80.85 80.03 L5 12.28 0.690 1988 list
2797 Teucer 89.430 111.14 113.99 L4 10.15 0.920 1981 list
2920 Automedon 88.574 111.01 113.11 L4 10.21 0.950 1981 list
(15436) 1998 VU30 87.646 85.71 78.63 L4 8.97 0.870 1998 list
3596 Meriones 87.380 75.09 73.28 L4 12.96 0.830 1985 list
2893 Peiroos 86.884 87.46 86.76 L5 8.96 0.950 1975 list
4086 Podalirius 85.495 86.89 85.98 L4 10.43 0.870 1985 list
4060 Deipylos 84.043 79.21 86.79 L4 9.30 0.760 1987 list
1404 Ajax 83.990 81.69 96.34 L4 29.38 0.960 1936 list
4348 Poulydamas 82.032 70.08 87.51 L5 9.91 0.840 1988 list
5144 Achates 80.958 91.91 89.85 L5 5.96 0.920 1991 list
4833 Meges 80.165 87.33 89.39 L4 14.25 0.940 1989 list
2223 Sarpedon 77.480 94.63 108.21 L5 22.74 0.880 1977 list
(4489) 1988 AK 76.595 92.93 95.02 L4 12.58 0.950 1988 list
2260 Neoptolemus 76.435 71.65 81.28 L4 8.18 0.950 1975 list
5254 Ulysses 76.147 78.34 80.00 L4 28.72 0.970 1986 list
(3708) 1974 FV1 75.661 79.59 76.75 L5 6.55 0.980 1974 list
2674 Pandarus 74.267 98.10 101.72 L5 8.48 1.000 1982 list
3564 Talthybius 73.730 68.92 74.11 L4 40.59 0.900 1985 list
4834 Thoas 72.331 86.82 96.21 L4 18.19 0.950 1989 list
(7641) 1986 TT6 71.839 68.97 75.28 L4 27.77 0.980 1986 list
3540 Protesilaos 70.225 76.84 87.66 L4 8.95 0.940 1973 list
(11395) 1998 XN77 68.977 64.71 67.78 L4 17.38 1998 list
(4035) 1986 WD 68.733 68.23 66.99 L4 13.47 0.970 1986 list
5264 Telephus 68.472 73.26 81.38 L4 9.53 0.970 1991 list
1868 Thersites 68.163 70.08 78.89 L4 10.48 0.960 1960 list
(9799) 1996 RJ 68.033 64.87 72.42 L4 21.52 0.910 1996 list
4068 Menestheus 67.625 62.37 68.46 L4 14.40 0.950 1973 list
(23135) 2000 AN146 66.230 58.29 68.50 L4 8.69 0.860 2000 list
2456 Palamedes 65.916 91.66 99.60 L4 7.24 0.920 1966 list
3709 Polypoites 65.297 99.09 85.23 L4 10.04 1.000 1985 list
1749 Telamon 64.898 81.06 69.14 L4 16.98 0.970 1949 list
3548 Eurybates 63.885 72.14 68.40 L4 8.71 0.730 1973 list
4543 Phoinix 63.836 62.79 69.54 L4 38.87 1.200 1989 list
12444 Prothoon 63.835 64.31 62.41 L5 15.82 1996 list
4836 Medon 63.277 67.73 78.70 L4 9.82 0.920 1989 list
(16070) 1999 RB101 63.191 64.13 68.98 L5 20.24 0.960 1999 list
(15440) 1998 WX4 62.519 66.48 71.88 L4 21.43 0.970 1998 list
(4715) 1989 TS1 62.097 63.91 65.93 L5 8.81 0.850 1989 list
(A) Used sources: WISE/NEOWISE catalog (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.

Naming[edit]

This minor planet was named from Greek mythology after the young Trojan prince Troilus, the son of King Priam (also see 884 Priamus), who in a medieval legend loved Cressida (see 548 Kressida) and lost her to Diomedes (see 1437 Diomedes). Troilus was killed by Achilles (see 588 Achilles) in the Trojan War. The official naming citation was published by Paul Herget in The Names of the Minor Planets in 1955 (H 112).[2]

References[edit]

  1. ^ a b c d e "1208 Troilus (1931 YA)". Minor Planet Center. Retrieved 12 June 2018. 
  2. ^ a b c Schmadel, Lutz D. (2007). Dictionary of Minor Planet Names – (1208) Troilus. Springer Berlin Heidelberg. p. 101. ISBN 978-3-540-00238-3. Retrieved 3 August 2017. 
  3. ^ a b c d e f g "JPL Small-Body Database Browser: 1208 Troilus (1931 YA)" (2018-05-25 last obs.). Jet Propulsion Laboratory. Retrieved 12 June 2018. 
  4. ^ a b c d e f g h i j "LCDB Data for (1208) Troilus". Asteroid Lightcurve Database (LCDB). Retrieved 12 June 2018. 
  5. ^ "List of Jupiter Trojans". Minor Planet Center. 30 May 2018. Retrieved 6 June 2018. 
  6. ^ a b c "Asteroid (1208) Troilus – Proper elements". AstDyS-2, Asteroids – Dynamic Site. Retrieved 12 June 2018. 
  7. ^ a b c d 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" (PDF). The Astrophysical Journal. 759 (1): 10. arXiv:1209.1549Freely accessible. Bibcode:2012ApJ...759...49G. doi:10.1088/0004-637X/759/1/49. Retrieved 12 June 2018.  (online catalog)
  8. ^ a b c d 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. Bibcode:2004PDSS...12.....T. Retrieved 15 June 2018. 
  9. ^ a b c d 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)
  10. ^ a b c French, L. M. (November 1987). "Rotation properties of four L5 Trojan asteroids from CCD photometry". Icarus: 325–341.MIT–supportedresearch. Bibcode:1987Icar...72..325F. doi:10.1016/0019-1035(87)90178-3. ISSN 0019-1035. Retrieved 22 November 2015. 
  11. ^ a b Molnar, Lawrence A.; Haegert, Melissa J.; Hoogeboom, Kathleen M. (June 2008). "Lightcurve Analysis of an Unbiased Sample of Trojan Asteroids". The Minor Planet Bulletin. 35 (2): 82–84. Bibcode:2008MPBu...35...82M. ISSN 1052-8091. Retrieved 22 November 2015. 
  12. ^ a b Behrend, Raoul. "Asteroids and comets rotation curves – (1208) Troilus". Geneva Observatory. Retrieved 3 August 2017. 
  13. ^ a b 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. 
  14. ^ Schaefer, Martha W.; Schaefer, Bradley E.; Rabinowitz, David L.; Tourtellotte, Suzanne W. (June 2010). "Phase curves of nine Trojan asteroids over a wide range of phase angles" (PDF). Icarus. 207 (2): 699–713. arXiv:0912.1888Freely accessible. Bibcode:2010Icar..207..699S. doi:10.1016/j.icarus.2009.11.031. Retrieved 12 June 2018. 
  15. ^ a b "Asteroid 1208 Troilus". Small Bodies Data Ferret. Retrieved 12 June 2018. 

External links[edit]