1208 Troilus
{{Short description|Asteroid sharing Jupiter's orbit}}
{{Use dmy dates|date=June 2018}}
{{Infobox planet
| minorplanet = yes
| name = 1208 Troilus
| background = #C2FFFF
| image = 1208 Troilus Hubble.jpg
| image_scale =
| caption = Hubble Space Telescope image of Troilus taken in 2012
| discoverer = K. Reinmuth
| discovery_site = Heidelberg Obs.
| discovered = 31 December 1931
| mpc_name = (1208) Troilus
| alt_names = 1931 YA{{·}}1965 WK
| adjective = Troilian
| pronounced = {{IPAc-en|ˈ|t|r|oʊ|ᵻ|l|ə|s|,_|ˈ|t|r|ɔɪ|l|ə|s}}Noah Webster (1884) A Practical Dictionary of the English Language{{dict.com|Troilus}}
| named_after = Troilus (Greek mythology)
| mp_category = Jupiter trojan
{{nowrap|Trojan{{·}}background}}
| epoch = 23 March 2018 (JD 2458200.5)
| uncertainty = 0
| observation_arc = 86.40 yr (31,557 d)
| aphelion = 5.7305 AU
| perihelion = 4.7712 AU
| semimajor = 5.2509 AU
| eccentricity = 0.0913
| period = 12.03 yr (4,395 d)
| mean_anomaly = 189.17°
| mean_motion = {{Deg2DMS|0.0819|sup=ms}} / day
| inclination = 33.542°
| asc_node = 48.546°
| arg_peri = 296.06°
| jupiter_moid = 0.001 AU
| tisserand = 2.6590
| mean_diameter = {{val|100.48|1.10|u=km}}
103.31 km (derived)
{{val|103.34|3.9|u=km}}
{{val|111.36|2.36|u=km}}
| rotation = {{val|24|ul=h}}
{{val|56.17|0.07|u=h}}
{{val|63.8|0.5|u=h}}
| albedo = {{val|0.037|0.002}}
{{val|0.0397}} (derived)
{{val|0.041|0.006}}
{{val|0.0419|0.003}}
| spectral_type = FCU (Tholen)
C0 (Barucci)
U–B {{=}} {{val|0.314|093}}
B–V = {{val|0.750|0.050}}
V–R = {{val|0.380|0.030}}
V–I = {{val|0.740|0.020}}
| abs_magnitude = 8.99
9.05
9.08
}}
1208 Troilus {{IPAc-en|ˈ|t|r|oʊ|ᵻ|l|ə|s}} is a large and notably inclined Jupiter trojan from the Trojan camp, approximately {{convert|103|km|mi|abbr=off|sp=us}} in diameter. It was discovered on 31 December 1931, by German astronomer Karl Reinmuth at the Heidelberg Observatory in southern Germany. The unusual F-type asteroid belongs to the largest Jupiter trojans and has a long rotation period of 56.2 hours. It was named after the Trojan prince Troilus, who was killed by Achilles.
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 {{crossreference|(see Trojans in astronomy)}}. It is also a non-family asteroid of the Jovian background population.
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. The body's observation arc begins with its official discovery observation at Heidelberg in December 1931.
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). It has also been characterized as a carbonaceous C-type in the Barucci taxonomy (C0-type).
= Rotation period =
In April 2007, a rotational lightcurve of Troilus was obtained from photometric observations by Lawrence Molnar at the Calvin-Rehoboth Robotic Observatory {{Obscode|G98}} in New Mexico. Lightcurve analysis gave a rotation period of {{val|56.17|0.07}} hours with a brightness variation of {{val|0.20|0.02}} magnitude ({{small|U=2}}). 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 {{Obscode|A12}}, which gave a period of 24 and 63.8 hours, respectively ({{small|U=2/1}}).
= 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. 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.
{{Largest Jupiter trojans}}
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 ({{small|H 112}}).
References
{{reflist|30em|refs=
|type = 2018-05-25 last obs.
|title = JPL Small-Body Database Browser: 1208 Troilus (1931 YA)
|url = https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2001208
|publisher = Jet Propulsion Laboratory
|access-date = 12 June 2018}}
|last = Schmadel | first = Lutz D.
|title = Dictionary of Minor Planet Names |publisher = Springer Berlin Heidelberg
|page = 101
|date = 2007
|isbn = 978-3-540-00238-3
|doi = 10.1007/978-3-540-29925-7_1209 |chapter = (1208) Troilus }}
|title = 1208 Troilus (1931 YA)
|work = Minor Planet Center
|url = https://www.minorplanetcenter.net/db_search/show_object?object_id=1208
|access-date = 12 June 2018}}
|title = List of Jupiter Trojans
|work = Minor Planet Center
|date = 30 May 2018
|url = https://www.minorplanetcenter.net/iau/lists/JupiterTrojans.html
|access-date = 6 June 2018}}
|title = Asteroids and comets rotation curves – (1208) Troilus
|last = Behrend |first = Raoul
|publisher = Geneva Observatory
|url = http://obswww.unige.ch/~behrend/page3cou.html#001208
|access-date = 3 August 2017}}
|first1 = T. |last1 = Grav
|first2 = A. K. |last2 = Mainzer
|first3 = J. M. |last3 = Bauer
|first4 = J. R. |last4 = Masiero
|first5 = C. R. |last5 = Nugent
|date = November 2012
|title = WISE/NEOWISE Observations of the Jovian Trojan Population: Taxonomy
|journal = The Astrophysical Journal
|volume = 759
|issue = 1
|page = 10
|bibcode = 2012ApJ...759...49G
|doi = 10.1088/0004-637X/759/1/49
|arxiv = 1209.1549
|s2cid = 119101711
}} ([http://vizier.cfa.harvard.edu/viz-bin/VizieR-6?-source=J/ApJ/759/49/table1&MPC=01208 online catalog])
|title = Asteroid (1208) Troilus – Proper elements
|publisher = AstDyS-2, Asteroids – Dynamic Site
|url = https://newton.spacedys.com/astdys/index.php?n=1208&pc=1.1.6
|access-date = 12 June 2018}}
|title = Asteroid 1208 Troilus
|work = Small Bodies Data Ferret
|url = https://sbntools.psi.edu/ferret/SimpleSearch/results.action?targetName=1208+Troilus
|access-date = 12 June 2018
|archive-date = 13 June 2018
|archive-url = https://web.archive.org/web/20180613014822/https://sbntools.psi.edu/ferret/SimpleSearch/results.action?targetName=1208%20Troilus
|url-status = dead
}}
|title = LCDB Data for (1208) Troilus
|publisher = Asteroid Lightcurve Database (LCDB)
|url = http://www.minorplanet.info/PHP/generateOneAsteroidInfo.php?AstInfo=1208%7CTroilus
|access-date = 12 June 2018}}
|display-authors = 6
|first1 = Fumihiko |last1 = Usui
|first2 = Daisuke |last2 = Kuroda
|first3 = Thomas G. |last3 = Müller
|first4 = Sunao |last4 = Hasegawa
|first5 = Masateru |last5 = Ishiguro
|first6 = Takafumi |last6 = Ootsubo
|first7 = Daisuke |last7 = Ishihara
|first8 = Hirokazu |last8 = Kataza
|first9 = Satoshi |last9 = Takita
|first10 = Shinki |last10 = Oyabu
|first11 = Munetaka |last11 = Ueno
|first12 = Hideo |last12 = Matsuhara
|first13 = Takashi |last13 = Onaka
|date = October 2011
|title = Asteroid Catalog Using Akari: AKARI/IRC Mid-Infrared Asteroid Survey
|journal = Publications of the Astronomical Society of Japan
|volume = 63
|issue = 5
|pages = 1117–1138
|bibcode = 2011PASJ...63.1117U
|doi = 10.1093/pasj/63.5.1117
|doi-access= free
}} ([http://vizier.cfa.harvard.edu/viz-bin/VizieR-5?-source=J/PASJ/63/1117/acua_v1&Num=1208 online], [https://core.ac.uk/download/pdf/43545172.pdf AcuA catalog p. 153])
|first1 = E. F. |last1 = Tedesco
|first2 = P. V. |last2 = Noah
|first3 = M. |last3 = Noah
|first4 = S. D. |last4 = Price
|date = October 2004
|title = IRAS Minor Planet Survey V6.0
|url = https://sbnarchive.psi.edu/pds3/iras/IRAS_A_FPA_3_RDR_IMPS_V6_0/data/diamalb.tab
|journal = NASA Planetary Data System – IRAS-A-FPA-3-RDR-IMPS-V6.0
|volume = 12
|pages = IRAS-A-FPA-3-RDR-IMPS-V6.0
|bibcode = 2004PDSS...12.....T
|access-date = 15 June 2018}}
|author = French, L. M.
|date = November 1987
|title = Rotation properties of four L5 Trojan asteroids from CCD photometry
|url = http://adsabs.harvard.edu/cgi-bin/bib_query?bibcode=1987Icar...72..325F
|journal = Icarus
|volume = 72
|issue = 2
|pages = 325–341.MIT–supportedresearch
|issn = 0019-1035
|bibcode = 1987Icar...72..325F
|doi = 10.1016/0019-1035(87)90178-3
|access-date= 22 November 2015}}
|author = Molnar, Lawrence A.
|author2 = Haegert, Melissa J.
|author3 = Hoogeboom, Kathleen M.
|date = June 2008
|title = Lightcurve Analysis of an Unbiased Sample of Trojan Asteroids
|url = http://adsabs.harvard.edu/cgi-bin/bib_query?bibcode=2008MPBu...35...82M
|journal = The Minor Planet Bulletin
|volume = 35
|issue = 2
|pages = 82–84
|issn = 1052-8091
|bibcode = 2008MPBu...35...82M
|access-date= 22 November 2015}}
|first1 = Martha W. |last1 = Schaefer
|first2 = Bradley E. |last2 = Schaefer
|first3 = David L. |last3 = Rabinowitz
|first4 = Suzanne W. |last4 = Tourtellotte
|date = June 2010
|title = Phase curves of nine Trojan asteroids over a wide range of phase angles
|journal = Icarus
|volume = 207
|issue = 2
|pages = 699–713
|bibcode = 2010Icar..207..699S
|doi = 10.1016/j.icarus.2009.11.031
|arxiv = 0912.1888|s2cid = 118589399
}}
|first1 = Joseph P. |last1 = Chatelain
|first2 = Todd J. |last2 = Henry
|first3 = Linda M. |last3 = French
|first4 = Jennifer G. |last4 = Winters
|first5 = David E. |last5 = Trilling
|date = June 2016
|title = Photometric colors of the brightest members of the Jupiter L5 Trojan cloud
|journal = Icarus
|volume = 271
|pages = 158–169
|bibcode = 2016Icar..271..158C
|doi = 10.1016/j.icarus.2016.01.026
|doi-access= free
}}
}}
External links
- [http://www.minorplanet.info/PHP/lcdbsummaryquery.php Asteroid Lightcurve Database (LCDB)], query form ([http://www.minorplanet.info/lightcurvedatabase.html info] {{Webarchive|url=https://web.archive.org/web/20171216050541/http://www.minorplanet.info/lightcurvedatabase.html |date=16 December 2017 }})
- [https://books.google.com/books?id=aeAg1X7afOoC&pg Dictionary of Minor Planet Names], Google books
- [http://obswww.unige.ch/~behrend/page_cou.html Asteroids and comets rotation curves, CdR] – Observatoire de Genève, Raoul Behrend
- [https://www.minorplanetcenter.net/iau/lists/NumberedMPs000001.html Discovery Circumstances: Numbered Minor Planets (1)-(5000)] – Minor Planet Center
- {{AstDys|1208}}
- {{JPL small body}}
{{Minor planets navigator |1207 Ostenia |number=1208 |1209 Pumma}}
{{Small Solar System bodies}}
{{Authority control}}
{{DEFAULTSORT:Troilus}}