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| image_size = 240
| image_size = 240
| caption = Star field showing Hektor ([[apparent magnitude|apmag]] 15)
| caption = Star field showing Hektor ([[apparent magnitude|apmag]] 15)
| discovery_ref = &thinsp;<ref name="MPC-object" />
| discoverer = [[August Kopff|A. Kopff]]
| discoverer = [[August Kopff|A. Kopff]]
| discovery_site = [[Heidelberg Observatory|Heidelberg Obs.]]
| discovery_site = [[Heidelberg Observatory|Heidelberg Obs.]]
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| pronounced = {{IPAc-en|ˈ|h|ɛ|k|t|ɔr}} {{Respell|HEK|tor}}
| pronounced = {{IPAc-en|ˈ|h|ɛ|k|t|ɔr}} {{Respell|HEK|tor}}
| adjectives = Hektorian
| adjectives = Hektorian
| named_after = [[Hector]] {{small|(Greek mythology)}}
| named_after = [[Hector]] {{small|(Greek mythology)}}<ref name="springer" />
| mp_category = {{nowrap|[[Jupiter trojan]]&thinsp;<ref name="jpldata" />{{·}}[[Hektor family|Hektor]]&thinsp;<ref name="Ferret" />}}<br />{{small|([[Greek camp]])}}<ref name="MPC-Jupiter-Trojans" />
| mp_category = {{nowrap|[[Jupiter trojan]]&thinsp;<ref name="MPC-object" /><ref name="jpldata" />{{·}}[[Hektor family|Hektor]]&thinsp;<ref name="Ferret" />}}<br />{{small|([[Greek camp]])}}<ref name="MPC-Jupiter-Trojans" />
| orbit_ref = &thinsp;<ref name="jpldata" />
| orbit_ref = &thinsp;<ref name="jpldata" />
| epoch = 4 September 2017 ([[Julian day|JD]] 2458000.5)
| epoch = 23 March 2018 ([[Julian day|JD]] 2458200.5)
| uncertainty = 0
| uncertainty = 0
| observation_arc = 110.08 yr (40,205 days)
| observation_arc = 111.28 [[Julian year (astronomy)|yr]] (40,646 d)
| aphelion = 5.3824 [[Astronomical unit|AU]]
| aphelion = 5.3824 [[Astronomical unit|AU]]
| perihelion = 5.1297 AU
| perihelion = 5.1319 AU
| semimajor = 5.2561 AU
| semimajor = 5.2571 AU
| eccentricity = 0.0240
| eccentricity = 0.0238
| period = 12.05 [[Julian year (astronomy)|yr]] (4,401 days)
| period = 12.05 yr (4,403 d)
| mean_anomaly = 119.93[[Degree (angle)|°]]
| mean_anomaly = 136.09[[Degree (angle)|°]]
| mean_motion = {{Deg2DMS|0.0818|sup=ms}} / day
| mean_motion = {{Deg2DMS|0.0818|sup=ms}} / day
| inclination = 18.167°
| inclination = 18.166°
| asc_node = 342.79°
| asc_node = 342.79°
| arg_peri = 185.02°
| arg_peri = 185.22°
| jupiter_moid = 0.276 AU
| jupiter_moid = 0.2752 AU
| tisserand = 2.8990
| tisserand = 2.8990
| satellites = 1 {{small|(Skamandrios; [[Diameter|D]]: {{val|12|3|u=km}}}}<ref name="Marchis-AJL2014" />
| satellites = 1 {{small|(Skamandrios; [[Diameter|D]]: {{val|12|3|u=km}}}}<ref name="Marchis-2014" />
| dimensions = 370&thinsp;×&thinsp;195&thinsp;×&thinsp;195&nbsp;km<ref name=Hubble1998 /><br />403&thinsp;×&thinsp;201&nbsp;km {{small|(derived)}}<ref name="Marchis-AJL2014" />
| dimensions = {{val|370|x|195|x|195|u=km}}<ref name="Storrs-1999" /><br />{{val|403|x|201|u=km}} {{small|(derived)}}<ref name="Marchis-2014" />
| mean_diameter = {{val|147.37|2.33|u=km}}<ref name="Grav-2012" /><br />225&nbsp;km<ref name="jpldata" /><br />{{val|226.68|15.15|u=km}}<ref name="Carry2012" /><br />{{val|230.99|3.94|u=km}}<ref name="AKARI" /><br />{{val|250|26|u=km}} {{small|(equivalent diameter)}}<ref name="Marchis-AJL2014" />
| mean_diameter = {{val|147.37|2.33|u=km}}<ref name="Grav-2012" /><br />{{val|225|u=km}}<ref name="jpldata" /><br />{{val|226.68|15.15|u=km}}<ref name="Carry-2012" /><br />{{val|230.99|3.94|u=km}}<ref name="AKARI" /><br />{{val|250|26|u=km}}<ref name="Marchis-2014" />
| mass = {{val|9.95|0.12|e=18|u=kg}}<ref name="Carry2012"/><br />{{val|7.9|1.4|e=18|u=kg}}<ref name="Marchis-AJL2014" />
| mass = {{val|9.95|0.12|e=18|u=kg}}<ref name="Carry-2012"/><br />{{val|7.9|1.4|e=18|u=kg}}<ref name="Marchis-2014" />
| density = {{val|1.0|0.3}}&thinsp;g/cm<sup>3</sup><ref name="Marchis-AJL2014" /><br />{{val|1.63|0.32}}&thinsp;g/cm<sup>3</sup><ref name="Carry2012" /><br />{{val|2.43|0.35}}&thinsp;g/cm<sup>3</sup><ref name="Descamps2015" />
| density = {{val|1.0|0.3|u=g/cm3}}<ref name="Marchis-2014" /><br />{{val|1.63|0.32|u=g/cm3}}<ref name="Carry-2012" /><br />{{val|2.43|0.35|u=g/cm3}}<ref name="Descamps-2015" />
| rotation = {{convert|6.9205|h|d}}<ref name=Marchis-AJL2014 /><br />
| rotation = {{convert|6.9205|h|d}}<ref name="Marchis-2014" /><br />
| albedo = 0.025<ref name="jpldata" /><br />{{val|0.034|0.001}}<ref name="AKARI" /><br />{{val|0.107|0.011}}<ref name="Grav-2012" />
| albedo = 0.025<ref name="jpldata" /><br />{{val|0.034|0.001}}<ref name="AKARI" /><br />{{val|0.107|0.011}}<ref name="Grav-2012" />
| angular_size = 0.078"<!-- Horizons 1955-Mar-17 --> to 0.048" {{citation needed|date=March 2018}}
| angular_size = 0.078"<!-- Horizons 1955-Mar-17 --> to 0.048" {{citation needed|date=March 2018}}
Line 44: Line 45:
}}
}}


'''624 Hektor''' ({{IPAc-en|ˈ|h|ɛ|k|t|ɔr}} {{Respell|HEK|tor}}) is the largest [[Jupiter trojan]] and the namesake of the [[Hektor family]], with a highly elongated shape equivalent in volume to a sphere of approximately 225 to 250 kilometers diameter. It was discovered on 10 February 1907, by astronomer [[August Kopff]] at [[Heidelberg Observatory]] in southwest Germany, and named after [[Hector]] from Greek mythology. It has one small (~12km) satellite, Skamandrios, discovered in 2006.
'''624 Hektor''' ({{IPAc-en|ˈ|h|ɛ|k|t|ɔr}} {{Respell|HEK|tor}}) is the largest [[Jupiter trojan]] and the namesake of the [[Hektor family]], with a highly elongated shape equivalent in volume to a sphere of approximately 225 to 250 kilometers diameter. It was discovered on 10 February 1907, by astronomer [[August Kopff]] at [[Heidelberg Observatory]] in southwest Germany, and named after the Trojan prince [[Hector]], from Greek mythology.<ref name="MPC-object" /><ref name="springer" /> It has one small 12-kilometer sized [[Minor-planet moon|satellite]], [[#Contact binary plus moon|Skamandrios]], discovered in 2006.


== Description ==
== Description ==
''Hektor'' is a [[D-type asteroid]], dark and reddish in colour. It lies in Jupiter's leading [[Lagrangian point]], {{L4}}, called the '[[List of Trojan asteroids (Greek camp)|Greek]]' node after one of the two sides in the legendary [[Trojan War]]. Hektor is named after the Trojan hero [[Hektor]] and is thus one of two trojan asteroids that is "misplaced" in the wrong camp (the other one being [[617 Patroclus]] in the [[List of Trojan asteroids (Trojan camp)|Trojan node]]).
''Hektor'' is a [[D-type asteroid]], dark and reddish in colour. It lies in Jupiter's leading [[Lagrangian point]], {{L4}}, called the [[Greek camp]] after one of the two sides in the legendary [[Trojan War]]. Hektor is named after the Trojan hero [[Hektor]] and is thus one of two trojan asteroids that is "misplaced" in the wrong camp (the other one being [[617&nbsp;Patroclus]] in the [[Trojan camp]]).


== Contact binary plus moon ==
== Contact binary plus moon ==
{{Redirect|Skamandrios (moon)|the mythological figure|Skamandrios}}
Hektor is one of the most elongated bodies of its size in the [[Solar System]], being approximately 403&nbsp;km in its longest dimension, but averaging only around 201&nbsp;km in its other dimensions, with a total volume equivalent to an approx 250&nbsp;km diameter sphere, and an estimated mass of {{val|7.9|e=18|u=kg}} (thus density of 1.0g/cm<sup>3</sup>). It is thought that Hektor might be a [[contact binary (asteroid)|contact binary]] (two asteroids joined by gravitational attraction) like [[216 Kleopatra]], composed of two more rounded lobes of 220 and 183&nbsp;km mean diameters<ref name="Marchis-AJL2014" />. [[Hubble Space Telescope]] observations of Hektor in 1993 did not show an obvious [[wikt:bilobate|bilobate]] shape because of a limited [[angular resolution]]. On 17 July 2006, the [[Keck telescopes|Keck]] 10-meter-II-telescope and its [[laser guide star]] [[adaptive optics]] (AO) system indicated a bilobate shape for Hektor<ref name=marchis-LGS>{{cite web | url=http://www.mpia-hd.mpg.de/PARSEC/Ring2007/TalksPostersPDF/Friday/TrojanAsteroids_FranckMarchis.pdf | author=Franck Marchis |title=Searching and Characterizing Multiple Trojan Asteroids with LGS AO Systems}}</ref>, which was reinforced by later studies that, together with multiple historical lightcurves, suggest a rotation period of 6.9205&nbsp;hours.<ref name="Marchis-AJL2014" />


Hektor is one of the most elongated bodies of its size in the [[Solar System]], being approximately 403&nbsp;km in its longest dimension, but averaging only around 201&nbsp;km in its other dimensions, with a total volume equivalent to an approx 250&nbsp;km diameter sphere, and an estimated mass of {{val|7.9|e=18|u=kg}} (thus density of 1.0g/cm<sup>3</sup>). It is thought that Hektor might be a [[contact binary (asteroid)|contact binary]] (two asteroids joined by gravitational attraction) like [[216 Kleopatra]], composed of two more rounded lobes of 220 and 183&nbsp;km mean diameters<ref name="Marchis-2014" />. [[Hubble Space Telescope]] observations of Hektor in 1993 did not show an obvious [[wikt:bilobate|bilobate]] shape because of a limited [[angular resolution]]. On 17 July 2006, the [[Keck telescopes|Keck]] 10-meter-II-telescope and its [[laser guide star]] [[adaptive optics]] (AO) system indicated a bilobate shape for Hektor<ref name="Marchis-LGS" />, which was reinforced by later studies that, together with multiple historical lightcurves, suggest a rotation period of 6.9205 hours.<ref name="Marchis-2014" />
Additionally, a 12-km-diameter moon of Hektor, named '''Skamandrios''', {{mp|S/2006 (624) 1}}, was detected orbiting with a semi-major axis of 623.5&nbsp;km and an orbital period of 2.9651&nbsp;days (71.162&nbsp;hours).<ref name=IAUC8732>{{cite web|url=http://www.cbat.eps.harvard.edu/iauc/08700/08732.html |title=IAUC 8732: S/2006 (624) 1 (Satellite Discovery) |accessdate=23 July 2006}}</ref><ref name="Marchis-AJL2014" /> It was confirmed with Keck observations in November 2011.<ref name=marchis-tweet>{{cite tweet|number=135034306958606336|user=AllPlanets|title=Dome closed, Keck telescope is...|date=11 November 2011}}</ref> No mass estimate was provided, but the equivalent volume suggests an approximate mass of {{val|8.74|e=14|u=kg}} if the two bodies are of the same density.


Additionally, a 12-km-diameter moon of Hektor, named '''Skamandrios''', {{mp|S/2006 (624) 1}}, was detected orbiting with a semi-major axis of 623.5&nbsp;km and an orbital period of 2.9651&nbsp;days (71.162&nbsp;hours).<ref name=IAUC8732 /><ref name="Marchis-2014" /> It was confirmed with Keck observations in November 2011.<ref name="Marchis-tweet" /> No mass estimate was provided, but the equivalent volume suggests an approximate mass of {{val|8.74|e=14|u=kg}} if the two bodies are of the same density.
Hektor is, so far, the only known binary trojan asteroid in the {{L4}} point and the first known trojan with a satellite companion. [[617 Patroclus]], another large trojan asteroid located in the {{L5}}, is composed of two almost equal-sized components.<ref name=marchis-LGS />

Hektor is, so far, the only known binary trojan asteroid in the {{L4}} point and the first known trojan with a satellite companion. [[617 Patroclus]], another large trojan asteroid located in the {{L5}}, is composed of two almost equal-sized components.<ref name="Marchis-LGS" />


{{JPL SBDB Jupiter Trojans}}
{{JPL SBDB Jupiter Trojans}}


==Studies==
== Studies ==
624 Hektor was in a 2003 study of asteroids using the Hubble [[Fine Guidance Sensor (HST)|FGS]].<ref>{{Cite journal|last=Tanga|first=P.|last2=Hestroffer|first2=D.|last3=Cellino|first3=A.|last4=Lattanzi|first4=M.|last5=Martino|first5=M. Di|last6=Zappalà|first6=V.|date=2003-04-01|title=Asteroid observations with the Hubble Space Telescope FGS|url=https://www.aanda.org/articles/aa/abs/2003/14/aa3023/aa3023.html|journal=Astronomy & Astrophysics|language=en|volume=401|issue=2|pages=733–741|doi=10.1051/0004-6361:20030032|issn=0004-6361|bibcode=2003A&A...401..733T}}</ref> Asteroids studied include [[63 Ausonia|(63) Ausonia]], [[15 Eunomia|(15) Eunomia]], [[43 Ariadne|(43) Ariadne]], [[44 Nysa|(44) Nysa,]] and (624) Hektor.<ref>{{Cite journal|last=Tanga|first=P.|last2=Hestroffer|first2=D.|last3=Cellino|first3=A.|last4=Lattanzi|first4=M.|last5=Martino|first5=M. Di|last6=Zappalà|first6=V.|date=2003-04-01|title=Asteroid observations with the Hubble Space Telescope FGS|url=https://www.aanda.org/articles/aa/abs/2003/14/aa3023/aa3023.html|journal=Astronomy & Astrophysics|language=en|volume=401|issue=2|pages=733–741|doi=10.1051/0004-6361:20030032|issn=0004-6361|bibcode=2003A&A...401..733T}}</ref>. It has since been revisited several times, particularly as a test of the upgraded resolution of the Keck Observatory's LGS Adaptive Optics system which allowed Earth-based observation of binary asteroids for the first time.<ref name=marchis-LGS /><ref name="Marchis-AJL2014" /> The asteroid has also been imaged by the [[NEOWISE]] and [[AKARI]] all-sky studies, which reported highly divergent size estimates of 147.4<ref name="Grav-2012" /> and 231.0&nbsp;kilometers <ref name="AKARI" /> respectively, although this mostly arises from large differences in estimated [[albedo]] (approximately 0.107 for NEOWISE, and a much lower 0.034 for AKARI) rather than its [[absolute magnitude]] being measured only briefly at opposing extremes of a widely varying cycle such as thought to account for the uncertainty over the size of [[1173 Anchises]] (624 Hektor's own abs. mag. recorded as a relatively similar 7.20 and 7.49 by the two studies). It is, unusually, not included in the published [[IRAS]] results, and is therefore the largest Jupiter trojan to be omitted from that study.
624 Hektor was in a 2003 study of asteroids using the Hubble [[Fine Guidance Sensor (HST)|FGS]].<ref name="Tanga-2003" /> Asteroids studied include [[63 Ausonia|(63) Ausonia]], [[15 Eunomia|(15) Eunomia]], [[43 Ariadne|(43) Ariadne]], [[44 Nysa|(44) Nysa,]] and (624) Hektor.<ref name="Tanga-2003" /> It has since been revisited several times, particularly as a test of the upgraded resolution of the Keck Observatory's LGS Adaptive Optics system which allowed Earth-based observation of binary asteroids for the first time.<ref name="Marchis-LGS" /><ref name="Marchis-2014" /> The asteroid has also been imaged by the [[NEOWISE]] and [[AKARI]] all-sky studies, which reported highly divergent size estimates of 147.4<ref name="Grav-2012" /> and 231.0&nbsp;kilometers <ref name="AKARI" /> respectively, although this mostly arises from large differences in estimated [[albedo]] (approximately 0.107 for NEOWISE, and a much lower 0.034 for AKARI) rather than its [[absolute magnitude]] being measured only briefly at opposing extremes of a widely varying cycle such as thought to account for the uncertainty over the size of [[1173 Anchises]] (624 Hektor's own abs. mag. recorded as a relatively similar 7.20 and 7.49 by the two studies). It is, unusually, not included in the published [[IRAS]] results, and is therefore the largest Jupiter trojan to be omitted from that study.


== See also ==
== See also ==
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{{reflist|refs=
{{reflist|refs=


<ref name=jpldata>
<ref name="jpldata">{{cite web
|type = 2018-05-25 last obs.
{{cite web
|title = JPL Small-Body Database Browser: 624 Hektor (1907 XM)
|type=5 September 2008 last obs
|url = https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2000624
|title=JPL Small-Body Database Browser: 624 Hektor (1907 XM)
|publisher = [[Jet Propulsion Laboratory]]
|url=http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=624
|accessdate=1 November 2008}}</ref>
|accessdate = 14 June 2018}}</ref>

<ref name="MPC-object">{{cite web
|title = 624 Hektor (1907 XM)
|work = Minor Planet Center
|url = https://www.minorplanetcenter.net/db_search/show_object?object_id=624
|accessdate = 14 June 2018}}</ref>

<ref name="springer">{{cite book
|title = Dictionary of Minor Planet Names – (624) Hektor
|last = Schmadel | first = Lutz D.
|publisher = Springer Berlin Heidelberg
|page = 63
|date = 2007
|url = https://link.springer.com/referenceworkentry/10.1007/978-3-540-29925-7_625
|isbn = 978-3-540-00238-3
|accessdate = 14 June 2018}}</ref>


<ref name="Grav-2012">{{cite journal
<ref name="Grav-2012">{{cite journal
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|accessdate = 19 October 2017}}</ref>
|accessdate = 19 October 2017}}</ref>


<!-- <ref name=Detal2994>
<ref name="Storrs-1999">{{Cite journal
|display-authors = 6
{{cite journal
|first1 = Alex |last1 = Storrs
|title=Pole, albedo and shape of the minor planets 624 Hektor and 43 Ariadne
|first2 = Ben |last2 = Weiss
|bibcode=1994A&A...281..269D
|first3 = Ben |last3 = Zellner
|last1=Detal |first1=A.
|first4 = Win |last4 = Burleson
|last2=Hainaut |first2=O.
|first5 = Rukmini |last5 = Sichitiu
|last3=Pospieszalska-Surdej |first3=A.
|first6 = Eddie |last6 = Wells
|last4=Schils |first4=P.
|first7 = Charles |last7 = Kowal
|last5=Schober |first5=H. J.
|first8 = David |last8 = Tholen
|last6=Surdej |first6=J.
|date = February 1999
|volume=281 |year=1994 |pages=269
|title = Imaging Observations of Asteroids with Hubble Space Telescope
|journal=Astronomy and Astrophysics
|url = https://pdfs.semanticscholar.org/ba43/528983a55b0ec70e42a997e13e553ef19b55.pdf
|issn=0004-6361}}</ref> -->
|journal = Icarus
|volume = 137
|issue = 2
|pages = 260–268
|bibcode = 1999Icar..137..260S
|doi = 10.1006/icar.1999.6047
|access-date= 14 June 2018}}</ref>


<ref name=Hubble1998>
<ref name="Carry-2012">{{Citation
|first1 = B.
{{cite journal
|last1 = Carry
|last=Storrs
|date = December 2012
|first=Alex
|title = Density of asteroids
|title=Imaging Observations of Asteroids with Hubble Space Telescope
|work = Planetary and Space Science
|journal=Icarus
|url = https://arxiv.org/pdf/1203.4336.pdf
|volume=137
|volume = 73
|pages=260–268
|pages = 98–118
|date=1998
|doi = 10.1016/j.pss.2012.03.009
|url=http://web.media.mit.edu/~win/hstpub.pdf
|bibcode = 2012P&SS...73...98C
|accessdate=22 May 2008
|arxiv = 1203.4336 }} See Table 1.</ref>
|doi=10.1006/icar.1999.6047
|bibcode=1999Icar..137..260S
|author2=Weiss, B.
|last3=Zellner
|first3=B.
|issue=2
|deadurl=yes
|archiveurl=https://web.archive.org/web/20081030022816/http://web.media.mit.edu/~win/hstpub.pdf
|archivedate=30 October 2008}}</ref>


<ref name="Carry2012">
<ref name="Marchis-2014">{{Cite journal
|display-authors = 6
{{citation
|first1=B.
|first1 = F. |last1 = Marchis
|first2 = J. |last2 = Durech
|last1=Carry
|first3 = J. |last3 = Castillo-Rogez
|title=Density of asteroids
|first4 = F. |last4 = Vachier
|work=Planetary and Space Science
|first5 = M. |last5 = Cuk
|volume=73
|first6 = J. |last6 = Berthier
|pages=98–118
|first7 = M. H. |last7 = Wong
|date=December 2012
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|bibcode= 2012P&SS...73...98C
|first10 = M. A. |last10 = van Dam
|postscript= .
|first11 = H. |last11 = Hamanowa
|arxiv=1203.4336}} See Table 1.</ref>
|first12 = M. |last12 = Viikinkoski

|date = March 2014
<ref name=Marchis-AJL2014>
|title = The Puzzling Mutual Orbit of the Binary Trojan Asteroid (624) Hektor
{{cite journal|last1=Marchis|first1=Frank|last2=Durech|first2=Josef|last3=Castillo-Rogez|first3=Julie|last4=Vachier|first4=Frédéric|last5=Ćuk|first5=Matija|last6=Berthier|first6=Jérôme|last7=Wong|first7=Michael H.|last8=Kalas|first8=Paul|last9=Duchene|first9=Gaspard|last10=van Dam|first10=Marcos A.|last11=Hamanowa|first11=H.|last12=Viikinkoski|first12=M.
|url = https://arxiv.org/pdf/1402.7336.pdf
|title=The Puzzling Mutual Orbit of the Binary Trojan Asteroid (624) Hektor
|journal=[[The Astrophysical Journal|The Astrophysical Journal Letters]]
|journal = The Astrophysical Journal Letters
|volume = 783
|date=28 February 2014
|issue = 2
|volume=L37
|page = 6
|issue=2014
|bibcode = 2014ApJ...783L..37M
|doi=10.1088/2041-8205/783/2/L37
|doi = 10.1088/2041-8205/783/2/L37
|arxiv = 1402.7336
|arxiv = 1402.7336
|bibcode = 2014ApJ...783L..37M}}</ref>
|access-date= 14 June 2018}}</ref>

<ref name="Descamps2015">
{{cite journal
|last1=Descamps
|first1=Pascal
|title=Dumb-bell-shaped equilibrium figures for fiducial contact-binary asteroids and EKBOs
|journal=Icarus
|volume=245
|date=2015
|pages=64–79
|issn=0019-1035
|doi=10.1016/j.icarus.2014.08.002
|arxiv = 1410.7962
|bibcode = 2015Icar..245...64D}}</ref>


<ref name="Descamps-2015">{{Cite journal
|last1 = Descamps
|first1 = Pascal
|date = January 2015
|title = Dumb-bell-shaped equilibrium figures for fiducial contact-binary asteroids and EKBOs
|url = https://arxiv.org/pdf/1410.7962.pdf
|journal = Icarus
|volume = 245
|pages = 64–79
|bibcode = 2015Icar..245...64D
|doi = 10.1016/j.icarus.2014.08.002
|arxiv = 1410.7962
|access-date= 14 June 2018}}</ref>


<ref name="AKARI">{{cite journal
<ref name="AKARI">{{cite journal
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|doi = 10.1093/pasj/63.5.1117
|doi = 10.1093/pasj/63.5.1117
|access-date= 13 June 2018}} ([http://vizier.cfa.harvard.edu/viz-bin/VizieR-5?-source=J/PASJ/63/1117/acua_v1&Num=624 online], [https://core.ac.uk/download/pdf/43545172.pdf AcuA catalog p. 153])</ref>
|access-date= 13 June 2018}} ([http://vizier.cfa.harvard.edu/viz-bin/VizieR-5?-source=J/PASJ/63/1117/acua_v1&Num=624 online], [https://core.ac.uk/download/pdf/43545172.pdf AcuA catalog p. 153])</ref>

<ref name="Tanga-2003">{{Cite journal
|display-authors = 6
|first1 = P. |last1 = Tanga
|first2 = D. |last2 = Hestroffer
|first3 = A. |last3 = Cellino
|first4 = M. |last4 = Lattanzi
|first5 = M. |last5 = Di Martino
|first6 = V. |last6 = Zappalà
|date = April 2003
|title = Asteroid observations with the Hubble Space Telescope. II. Duplicity search and size measurements for 6 asteroids
|url = https://www.aanda.org/articles/aa/pdf/2003/14/aa3023.pdf
|journal = Astronomy and Astrophysics
|pages = 733–741
|bibcode = 2003A&A...401..733T
|doi = 10.1051/0004-6361:20030032
|access-date= 14 June 2018}}</ref>

<ref name="Marchis-LGS">{{cite web
|author = Franck Marchis
|title = Searching and Characterizing Multiple Trojan Asteroids with LGS AO Systems
|date = November 2005
|type = PDF
|url = http://www.mpia-hd.mpg.de/PARSEC/Ring2007/TalksPostersPDF/Friday/TrojanAsteroids_FranckMarchis.pdf
|access-date= 14 June 2018}}</ref>

<ref name=IAUC8732>{{cite web
|title = IAUC 8732: S/2006 (624) 1 (Satellite Discovery)
|date = 21 July 2006
|work = Central Bureau for Astronomical Telegrams
|publisher = International Astronomical Union
|url = http://www.cbat.eps.harvard.edu/iauc/08700/08732.html
|accessdate = 14 June 2018}}</ref>

<ref name="Marchis-tweet">{{cite tweet
|number = 135034306958606336
|user = AllPlanets
|title = Dome closed, Keck telescope is...
|date = 11 November 2011}}</ref>


}} <!-- end of reflist -->
}} <!-- end of reflist -->
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{{Use dmy dates|date=June 2018}}
{{Use dmy dates|date=June 2018}}
{{Minor planets navigator|623 Chimaera|number=624|625 Xenia}}
{{Minor planets navigator |623 Chimaera |number=624 |625 Xenia}}
{{Small Solar System bodies}}
{{Small Solar System bodies}}


{{DEFAULTSORT:000624}}
{{DEFAULTSORT:Hektor}}
[[Category:Jupiter trojans (Greek camp)]]
[[Category:Jupiter trojans (Greek camp)|000624]]
[[Category:Numbered minor planets]]
[[Category:Numbered minor planets|000624]]
[[Category:Discoveries by August Kopff|Hektor]]
[[Category:Discoveries by August Kopff]]
[[Category:Minor planets named from Greek mythology|Hektor]]
[[Category:Minor planets named from Greek mythology]]
[[Category:Named minor planets|Hektor]]
[[Category:Named minor planets]]
[[Category:Binary asteroids]]
[[Category:Binary asteroids|000624]]
[[Category:Contact binary (asteroid)]]
[[Category:Contact binary (asteroid)|000624]]
[[Category:D-type asteroids (Tholen)]]
[[Category:D-type asteroids (Tholen)|000624]]
[[Category:Astronomical objects discovered in 1907|19070210]]
[[Category:Astronomical objects discovered in 1907|19070210]]

Revision as of 16:51, 14 June 2018

624 Hektor
Star field showing Hektor (apmag 15)
Discovery [1]
Discovered byA. Kopff
Discovery siteHeidelberg Obs.
Discovery date10 February 1907
Designations
(624) Hektor
Pronunciation/ˈhɛktɔːr/ HEK-tor
Named after
Hector (Greek mythology)[2]
1907 XM; 1948 VD
Jupiter trojan [1][3] · Hektor [4]
(Greek camp)[5]
AdjectivesHektorian
Orbital characteristics [3]
Epoch 23 March 2018 (JD 2458200.5)
Uncertainty parameter 0
Observation arc111.28 yr (40,646 d)
Aphelion5.3824 AU
Perihelion5.1319 AU
5.2571 AU
Eccentricity0.0238
12.05 yr (4,403 d)
136.09°
0° 4m 54.48s / day
Inclination18.166°
342.79°
185.22°
Known satellites1 (Skamandrios; D: 12±3 km[6]
Jupiter MOID0.2752 AU
TJupiter2.8990
Physical characteristics
Dimensions370 km × 195 km × 195 km[7]
403 km × 201 km (derived)[6]
Mean diameter
147.37±2.33 km[8]
225 km[3]
226.68±15.15 km[9]
230.99±3.94 km[10]
250±26 km[6]
Mass(9.95±0.12)×1018 kg[9]
(7.9±1.4)×1018 kg[6]
Mean density
1.0±0.3 g/cm3[6]
1.63±0.32 g/cm3[9]
2.43±0.35 g/cm3[11]
6.9205 hours (0.28835 d)[6]
0.025[3]
0.034±0.001[10]
0.107±0.011[8]
D (Tholen)[3]
13.79 to 15.26 [citation needed]
7.20[8] · 7.3[3] · 7.49[10]
0.078" to 0.048" [citation needed]

624 Hektor (/ˈhɛktɔːr/ HEK-tor) is the largest Jupiter trojan and the namesake of the Hektor family, with a highly elongated shape equivalent in volume to a sphere of approximately 225 to 250 kilometers diameter. It was discovered on 10 February 1907, by astronomer August Kopff at Heidelberg Observatory in southwest Germany, and named after the Trojan prince Hector, from Greek mythology.[1][2] It has one small 12-kilometer sized satellite, Skamandrios, discovered in 2006.

Description

Hektor is a D-type asteroid, dark and reddish in colour. It lies in Jupiter's leading Lagrangian point, L4, called the Greek camp after one of the two sides in the legendary Trojan War. Hektor is named after the Trojan hero Hektor and is thus one of two trojan asteroids that is "misplaced" in the wrong camp (the other one being 617 Patroclus in the Trojan camp).

Contact binary plus moon

"Skamandrios (moon)" redirects here. For the mythological figure, see Skamandrios.

Hektor is one of the most elongated bodies of its size in the Solar System, being approximately 403 km in its longest dimension, but averaging only around 201 km in its other dimensions, with a total volume equivalent to an approx 250 km diameter sphere, and an estimated mass of 7.9×1018 kg (thus density of 1.0g/cm3). It is thought that Hektor might be a contact binary (two asteroids joined by gravitational attraction) like 216 Kleopatra, composed of two more rounded lobes of 220 and 183 km mean diameters[6]. Hubble Space Telescope observations of Hektor in 1993 did not show an obvious bilobate shape because of a limited angular resolution. On 17 July 2006, the Keck 10-meter-II-telescope and its laser guide star adaptive optics (AO) system indicated a bilobate shape for Hektor[12], which was reinforced by later studies that, together with multiple historical lightcurves, suggest a rotation period of 6.9205 hours.[6]

Additionally, a 12-km-diameter moon of Hektor, named Skamandrios, S/2006 (624) 1, was detected orbiting with a semi-major axis of 623.5 km and an orbital period of 2.9651 days (71.162 hours).[13][6] It was confirmed with Keck observations in November 2011.[14] No mass estimate was provided, but the equivalent volume suggests an approximate mass of 8.74×1014 kg if the two bodies are of the same density.

Hektor is, so far, the only known binary trojan asteroid in the L4 point and the first known trojan with a satellite companion. 617 Patroclus, another large trojan asteroid located in the L5, is composed of two almost equal-sized components.[12]

The largest Jupiter trojans
Trojan Diameter (km)
624 Hektor 225
617 Patroclus 140
911 Agamemnon 131
588 Achilles 130
3451 Mentor 126
3317 Paris 119
1867 Deiphobus 118
1172 Äneas 118
1437 Diomedes 118
1143 Odysseus 115
Source: JPL Small-Body Database, NEOWISE data

Studies

624 Hektor was in a 2003 study of asteroids using the Hubble FGS.[15] Asteroids studied include (63) Ausonia, (15) Eunomia, (43) Ariadne, (44) Nysa, and (624) Hektor.[15] It has since been revisited several times, particularly as a test of the upgraded resolution of the Keck Observatory's LGS Adaptive Optics system which allowed Earth-based observation of binary asteroids for the first time.[12][6] The asteroid has also been imaged by the NEOWISE and AKARI all-sky studies, which reported highly divergent size estimates of 147.4[8] and 231.0 kilometers [10] respectively, although this mostly arises from large differences in estimated albedo (approximately 0.107 for NEOWISE, and a much lower 0.034 for AKARI) rather than its absolute magnitude being measured only briefly at opposing extremes of a widely varying cycle such as thought to account for the uncertainty over the size of 1173 Anchises (624 Hektor's own abs. mag. recorded as a relatively similar 7.20 and 7.49 by the two studies). It is, unusually, not included in the published IRAS results, and is therefore the largest Jupiter trojan to be omitted from that study.

See also

References

  1. ^ a b c "624 Hektor (1907 XM)". Minor Planet Center. Retrieved 14 June 2018.
  2. ^ a b Schmadel, Lutz D. (2007). Dictionary of Minor Planet Names – (624) Hektor. Springer Berlin Heidelberg. p. 63. ISBN 978-3-540-00238-3. Retrieved 14 June 2018.
  3. ^ a b c d e f "JPL Small-Body Database Browser: 624 Hektor (1907 XM)" (2018-05-25 last obs.). Jet Propulsion Laboratory. Retrieved 14 June 2018.
  4. ^ "Small Bodies Data Ferret". Nesvorny HCM Asteroid Families V3.0. Retrieved 19 October 2017.
  5. ^ "List of Jupiter Trojans". Minor Planet Center. 4 October 2017. Retrieved 19 October 2017.
  6. ^ a b c d e f g h i j Marchis, F.; Durech, J.; Castillo-Rogez, J.; Vachier, F.; Cuk, M.; Berthier, J.; et al. (March 2014). "The Puzzling Mutual Orbit of the Binary Trojan Asteroid (624) Hektor" (PDF). The Astrophysical Journal Letters. 783 (2): 6. arXiv:1402.7336. Bibcode:2014ApJ...783L..37M. doi:10.1088/2041-8205/783/2/L37. Retrieved 14 June 2018.
  7. ^ Storrs, Alex; Weiss, Ben; Zellner, Ben; Burleson, Win; Sichitiu, Rukmini; Wells, Eddie; et al. (February 1999). "Imaging Observations of Asteroids with Hubble Space Telescope" (PDF). Icarus. 137 (2): 260–268. Bibcode:1999Icar..137..260S. doi:10.1006/icar.1999.6047. Retrieved 14 June 2018.
  8. ^ 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:1209.1549. Bibcode:2012ApJ...759...49G. doi:10.1088/0004-637X/759/1/49. Retrieved 13 June 2018. (online catalog)
  9. ^ a b c Carry, B. (December 2012), "Density of asteroids" (PDF), Planetary and Space Science, vol. 73, pp. 98–118, arXiv:1203.4336, Bibcode:2012P&SS...73...98C, doi:10.1016/j.pss.2012.03.009 See Table 1.
  10. ^ 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 13 June 2018. (online, AcuA catalog p. 153)
  11. ^ Descamps, Pascal (January 2015). "Dumb-bell-shaped equilibrium figures for fiducial contact-binary asteroids and EKBOs" (PDF). Icarus. 245: 64–79. arXiv:1410.7962. Bibcode:2015Icar..245...64D. doi:10.1016/j.icarus.2014.08.002. Retrieved 14 June 2018.
  12. ^ a b c Franck Marchis (November 2005). "Searching and Characterizing Multiple Trojan Asteroids with LGS AO Systems" (PDF) (PDF). Retrieved 14 June 2018.
  13. ^ "IAUC 8732: S/2006 (624) 1 (Satellite Discovery)". Central Bureau for Astronomical Telegrams. International Astronomical Union. 21 July 2006. Retrieved 14 June 2018.
  14. ^ @AllPlanets (11 November 2011). "Dome closed, Keck telescope is..." (Tweet) – via Twitter.
  15. ^ a b Tanga, P.; Hestroffer, D.; Cellino, A.; Lattanzi, M.; Di Martino, M.; Zappalà, V. (April 2003). "Asteroid observations with the Hubble Space Telescope. II. Duplicity search and size measurements for 6 asteroids" (PDF). Astronomy and Astrophysics: 733–741. Bibcode:2003A&A...401..733T. doi:10.1051/0004-6361:20030032. Retrieved 14 June 2018. {{cite journal}}: Invalid |display-authors=6 (help)

External links

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