{{Short description|Jovian trojan}} {{Use dmy dates|date=June 2018}} {{Infobox planet | minorplanet = yes | name = 7641 Cteatus | background = #C2FFFF | image = | image_size = | caption = | discovery_ref = <ref name="MPC-object" /> | discoverer = M. Antal | discovery_site = Toruń–Piwnice | discovered = 5 October 1986 | mpc_name = (7641) Cteatus | alt_names = {{mp|1986 TT|6}}{{·}}{{mp|1975 VT|5}}<br />{{mp|1975 XS|4}}{{·}}{{mp|1986 VP|5}}<br />1991 HY{{·}}{{mp|1996 RN|26}} | adjective = Cteatian | pronounced = | named_after = Cteatus<ref name="WGSBN-Bulletin-Archive" /><br />{{small|(Greek mythology)}} | mp_category = Jupiter trojan<ref name="MPC-object" /><ref name="jpldata" /><ref name="lcdb" /><br />{{nowrap|Greek<ref name="MPC-Jupiter-Trojans" /><ref name="AstDys-object" />{{·}}background<ref name="AstDys-object" />}} | orbit_ref = <ref name="jpldata" /> | epoch = 23 March 2018 (JD 2458200.5) | uncertainty = 0 | observation_arc = 42.54 yr (15,539 d) | aphelion = 5.4898 AU | perihelion = 4.9398 AU | semimajor = 5.2148 AU | eccentricity = 0.0527 | period = 11.91 yr (4,350 d) | mean_anomaly = 171.71° | mean_motion = {{Deg2DMS|0.0828|sup=ms}} / day | inclination = 34.693° | asc_node = 242.06° | arg_peri = 228.81° | jupiter_moid = 0.0165 AU | tisserand = 2.6420 | mean_diameter = {{val|68.89|ul=km}} {{small|(derived)}}<ref name="lcdb" /><br />{{val|68.97|3.2|u=km }}<ref name="SIMPS" /><br />{{val|71.84|1.64|u=km}}<ref name="Grav-2012" /><br />{{val|75.28|2.43|u=km}}<ref name="AKARI" /> | rotation = {{val|27.770|0.013|ul=h}}<ref name="Mottola-2011" /> | albedo = {{val|0.062|0.005}}<ref name="AKARI" /><br />{{val|0.0647}} {{small|(derived)}}<ref name="lcdb" /><br />{{val|0.065|0.011}}<ref name="Grav-2012" /><br />{{val|0.0708|0.007}}<ref name="SIMPS" /> | spectral_type = D {{small|(Pan-STARRS)}}<ref name="Veres-2015" /><br />D {{small|(SDSS-MOC)}}<ref name="SDSS-Taxonomy" /><br />C {{small|(assumed)}}<ref name="lcdb" /><br />V–I {{=}} {{val|0.980|0.035}}<ref name="lcdb" /> | abs_magnitude = {{val|9.09|0.41}}<ref name="Veres-2015" /><br />9.30<ref name="SIMPS" /><ref name="Grav-2012" /><ref name="AKARI" /><br />9.4<ref name="MPC-object" /><ref name="jpldata" /><ref name="lcdb" /> }}
'''7641 Cteatus''', ''provisional designation'': {{mp|1986 TT|6}}, is a large Jupiter trojan from the Greek camp, approximately {{convert|70|km|mi|abbr=off|sigfig=2|sp=us}} in diameter. It was discovered on 5 October 1986, by Slovak astronomer Milan Antal at the Toruń Centre for Astronomy in Piwnice, Poland.<ref name="MPC-object" /> The dark D-type asteroid is notably inclined and has longer-than-average rotation period of 27.8 hours.<ref name="lcdb" /> It belongs to the 50 largest Jupiter trojans. It was named from Greek mythology for Cteatus, the conjoined twin and father of Amphimachus.<ref name="WGSBN-Bulletin-Archive" />
== Orbit and classification == thumb|200px|left|Inclined orbit of ''Cteatus''
''Cteatus'' is a dark Jovian asteroid orbiting in the leading Greek camp at Jupiter's {{L4}} Lagrangian point, 60° ahead of its orbit in a 1:1 resonance ''(see Trojans in astronomy)''. It is also a non-family asteroid in the Jovian background population.<ref name="AstDys-object" /><ref name="Ferret" />
It orbits the Sun at a distance of 4.9–5.5 AU once every 11 years and 11 months (4,350 days; semi-major axis of 5.21 AU). Its orbit has an eccentricity of 0.05 and a notably high inclination of 35° with respect to the ecliptic.<ref name="jpldata" /> The asteroid was first observed as ''{{mp|1975 VT|5}}'' at Crimea–Nauchnij in November 1975. The body's observation arc begins with its official discovery observation at the Toruń Centre.<ref name="MPC-object" />
== Numbering and naming ==
This minor planet was numbered by the Minor Planet Center on 22 May 1997 ({{small|M.P.C. 29897}}).<ref name="MPC-Circulars-Archive" /> On 14 May 2021, the object was named by the Working Group for Small Bodies Nomenclature (WGSBN), after Cteatus from Greek mythology, who had a conjoined twin. His son Amphimachus was one of the leaders of the Elean contingent in the Trojan War.<ref name="WGSBN-Bulletin-Archive" />
== Physical Characteristics ==
In the SDSS-based taxonomy, ''Cteatus'' is a dark D-type asteroid.<ref name="SDSS-Taxonomy" /> It has also been characterized as a D-type by Pan-STARRS{{'}} survey.<ref name="lcdb" /><ref name="Veres-2015" /> Its V–I color index of 0.98 agrees with that of most Jovian D-type asteroids.<ref name="lcdb" />
=== Rotation period ===
In October 2009, a rotational lightcurve of ''Cteatus'' was obtained from photometric observations by Italian astronomer Stefano Mottola at the Calar Alto Observatory in Spain. Lightcurve analysis gave a well-defined rotation period of 27.770 hours with a brightness amplitude of 0.40 magnitude ({{small|U=3}}).<ref name="lcdb" /><ref name="Mottola-2011" /> While not being a slow rotator, its period is significantly longer than that of most larger Jupiter trojans, which have a spin rate of typically 10 hours. The body's relatively high brightness variation of 0.40 magnitude is also indicative of a non-spherical shape.
=== 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, this asteroid measures between 68.97 and 75.28 kilometers in diameter and its surface has an albedo between 0.062 and 0.071.<ref name="SIMPS" /><ref name="Grav-2012" /><ref name="AKARI" /> The ''Collaborative Asteroid Lightcurve Link'' derives an albedo of 0.0647 and a diameter of 68.89 kilometers based on an absolute magnitude of 9.4.<ref name="lcdb" />
{{Largest Jupiter trojans}}
== References == {{reflist|30em|refs=
<ref name="jpldata">{{cite web |type = 2018-05-20 last obs. |title = JPL Small-Body Database Browser: 7641 (1986 TT6) |url = https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2007641 |publisher = Jet Propulsion Laboratory |accessdate = 10 June 2018}}</ref>
<ref name="MPC-object">{{cite web |title = 7641 (1986 TT6) |work = Minor Planet Center |url = https://www.minorplanetcenter.net/db_search/show_object?object_id=7641 |accessdate = 10 June 2018}}</ref>
<ref name="MPC-Jupiter-Trojans">{{cite web |title = List of Jupiter Trojans |work = Minor Planet Center |date = 30 May 2018 |url = https://www.minorplanetcenter.net/iau/lists/JupiterTrojans.html |accessdate = 10 June 2018}}</ref>
<ref name="MPC-Circulars-Archive">{{cite web |title = MPC/MPO/MPS Archive |work = Minor Planet Center |url = https://www.minorplanetcenter.net/iau/ECS/MPCArchive/MPCArchive_TBL.html |accessdate = 10 June 2018}}</ref>
<ref name="WGSBN-Bulletin-Archive">{{cite web |title = WGSBN Bulletin Archive |work = Working Group for Small Bodies Nomenclature |date = 14 May 2021 |url = https://www.wgsbn-iau.org/files/Bulletins/index.html |accessdate = 16 May 2021}} ([https://www.wgsbn-iau.org/files/Bulletins/V001/WGSBNBull_V001_001.pdf Bulletin #1])</ref>
<ref name="Grav-2012">{{cite journal |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=07641 online catalog])</ref>
<ref name="AstDys-object">{{cite web |title = Asteroid (7641) 1986 TT6 |publisher = AstDyS-2, Asteroids – Dynamic Site |url = https://newton.spacedys.com/astdys/index.php?n=7641&pc=1.1.6 |accessdate = 10 June 2018}}</ref>
<ref name="Ferret">{{cite web |title = Asteroid (7641) 1986 TT6 |work = Small Bodies Data Ferret |url = https://sbntools.psi.edu/ferret/SimpleSearch/results.action?targetName=7641 |accessdate = 10 June 2018}}</ref>
<ref name="SIMPS">{{cite journal |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 |accessdate = 15 June 2018}}</ref>
<ref name="SDSS-Taxonomy">{{Cite journal |first1 = J. M. |last1 = Carvano |first2 = P. H. |last2 = Hasselmann |first3 = D. |last3 = Lazzaro |first4 = T. |last4 = Mothé-Diniz |date = February 2010 |title = SDSS-based taxonomic classification and orbital distribution of main belt asteroids |url = https://sbnarchive.psi.edu/pds3/non_mission/EAR_A_I0035_5_SDSSTAX_V1_1/data/sdsstax_ast_table.tab |journal = Astronomy and Astrophysics |volume = 510 |page = 12 |bibcode = 2010A&A...510A..43C |doi = 10.1051/0004-6361/200913322 |access-date= 30 October 2019|doi-access= free }} [https://sbn.psi.edu/pds/resource/sdsstax.html (PDS data set)]</ref>
<ref name="lcdb">{{cite LCDB|number = 7641 |accessdate = 10 June 2018}}</ref>
<ref name="AKARI">{{cite journal |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= }} ([http://vizier.cfa.harvard.edu/viz-bin/VizieR-5?-source=J/PASJ/63/1117/acua_v1&Num=7641 online], [https://core.ac.uk/download/pdf/43545172.pdf AcuA catalog p. 153])</ref>
<ref name="Mottola-2011">{{cite journal |display-authors = 6 |first1 = Stefano |last1 = Mottola |first2 = Mario |last2 = Di Martino |first3 = Anders |last3 = Erikson |first4 = Maria |last4 = Gonano-Beurer |first5 = Albino |last5 = Carbognani |first6 = Uri |last6 = Carsenty |first7 = Gerhard |last7 = Hahn |first8 = Hans-Josef |last8 = Schober |first9 = Felix |last9 = Lahulla |first10 = Marco |last10 = Delbò |first11 = Claes-Ingvar |last11 = Lagerkvist |date = May 2011 |title = Rotational Properties of Jupiter Trojans. I. Light Curves of 80 Objects |journal = The Astronomical Journal |volume = 141 |issue = 5 |page = 32 |bibcode = 2011AJ....141..170M |doi = 10.1088/0004-6256/141/5/170 |doi-access= free |url= https://www.openaccessrepository.it/record/99323/files/fulltext.pdf |archive-url= https://web.archive.org/web/20240113171343/https://www.openaccessrepository.it/record/99323/files/fulltext.pdf |url-status= dead |archive-date= 13 January 2024 }}</ref>
<ref name="Veres-2015">{{cite journal |display-authors = 6 |first1 = Peter |last1 = Veres |first2 = Robert |last2 = Jedicke |first3 = Alan |last3 = Fitzsimmons |first4 = Larry |last4 = Denneau |first5 = Mikael |last5 = Granvik |first6 = Bryce |last6 = Bolin |first7 = Serge |last7 = Chastel |first8 = Richard J. |last8 = Wainscoat |first9 = William S. |last9 = Burgett |first10 = Kenneth C. |last10 = Chambers |first11 = Heather |last11 = Flewelling |first12 = Nick |last12 = Kaiser |first13 = Eugen A. |last13 = Magnier |first14 = Jeff S. |last14 = Morgan |first15 = Paul A. |last15 = Price |first16 = John L. |last16 = Tonry |first17 = Christopher |last17 = Waters |date = November 2015 |title = Absolute magnitudes and slope parameters for 250,000 asteroids observed by Pan-STARRS PS1 - Preliminary results |journal = Icarus |volume = 261 |pages = 34–47 |bibcode = 2015Icar..261...34V |doi = 10.1016/j.icarus.2015.08.007 |arxiv = 1506.00762 |s2cid = 53493339 }}</ref>
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== 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://www.minorplanetcenter.net/iau/lists/NumberedMPs005001.html Discovery Circumstances: Numbered Minor Planets (5001)-(10000)] – Minor Planet Center * {{AstDys|7641}} * {{JPL small body}}
{{Minor planets navigator |7640 Marzari |number=7641 |(7642) 1988 TZ}} {{Small Solar System bodies}} {{Authority control}}
{{DEFAULTSORT:Cteatus}} 007641 Category:Discoveries by Milan Antal Category:Named minor planets 19861005