1208_Troilus

1208 Troilus

1208 Troilus

Asteroid sharing Jupiter's orbit

1208 Troilus /ˈtroʊɪləs/ 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.[6] It was named after the Trojan prince Troilus, who was killed by Achilles.[4]

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Orbit and classification

Troilus is a dark 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.[8][17]

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.[5] The body's observation arc begins with its official discovery observation at Heidelberg in December 1931.[1]

Physical characteristics

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).[5][6] It has also been characterized as a carbonaceous C-type in the Barucci taxonomy (C0-type).[17]

Rotation period

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).[6][13] 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).[12][14]

Diameter and albedo

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.[9][10][11] 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.[6]

More information Largest Jupiter Trojans by survey(A) (mean-diameter in kilometers; YoD: Year of Discovery), Designation ...
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Naming

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).[4]

References

  1. [1]
    "1208 Troilus (1931 YA)". Minor Planet Center. Retrieved 12 June 2018.
  2. [2]
    Noah Webster (1884) A Practical Dictionary of the English Language
  3. [3]
    "Troilus". Dictionary.com Unabridged (Online). n.d.
  4. [4]
    Schmadel, Lutz D. (2007). "(1208) Troilus". Dictionary of Minor Planet Names. Springer Berlin Heidelberg. p. 101. doi:10.1007/978-3-540-29925-7_1209. ISBN 978-3-540-00238-3.
  5. [5]
    "JPL Small-Body Database Browser: 1208 Troilus (1931 YA)" (2018-05-25 last obs.). Jet Propulsion Laboratory. Retrieved 12 June 2018.
  6. [6]
    "LCDB Data for (1208) Troilus". Asteroid Lightcurve Database (LCDB). Retrieved 12 June 2018.
  7. [7]
    "List of Jupiter Trojans". Minor Planet Center. 30 May 2018. Retrieved 6 June 2018.
  8. [8]
    "Asteroid (1208) Troilus – Proper elements". AstDyS-2, Asteroids – Dynamic Site. Retrieved 12 June 2018.
  9. [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. S2CID 119101711. (online catalog)
  10. [10]
    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.
  11. [11]
    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. (online, AcuA catalog p. 153)
  12. [12]
    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 22 November 2015.
  13. [13]
    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.
  14. [14]
    Behrend, Raoul. "Asteroids and comets rotation curves – (1208) Troilus". Geneva Observatory. Retrieved 3 August 2017.
  15. [15]
    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.
  16. [16]
    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". Icarus. 207 (2): 699–713. arXiv:0912.1888. Bibcode:2010Icar..207..699S. doi:10.1016/j.icarus.2009.11.031. S2CID 118589399.
  17. [17]
    "Asteroid 1208 Troilus". Small Bodies Data Ferret. Retrieved 12 June 2018.
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