624 Hektor

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624 Hektor
Tholen)[4]
13.79 to 15.26 [citation needed]
7.20[9] · 7.3[4] · 7.49[11]
0.078" to 0.048" [citation needed]

624 Hektor

Heidelberg Observatory in southwest Germany, and named after the Trojan prince Hector, from Greek mythology.[1][3] It has one small 12-kilometer sized satellite, Skamandrios, discovered in 2006.[7]

Description

Hektor is a

Trojan camp
).

Contact-binary hypothesis

Modelled shape of 624 Hektor from its light curve.

Hektor is one of the most elongated bodies of its size in the

Keck 10-meter-II-telescope and its laser guide star adaptive optics (AO) system indicated a bilobate shape for Hektor,[13] which was reinforced by later studies that, together with multiple historical lightcurves, suggest a rotation period of 6.9205 hours.[7]

Satellite

"Skamandrios (moon)" redirects here. For the mythological figure, see Scamandrius.
Skamandrios
Discovery[7]
Discovered byMarchis et al.
Discovery date2006 July 16
Designations
Designation
Hektor I
Pronunciation/skəˈmændriəs/
Named after
Scamandrius
S/2006 (624) 1
AdjectivesSkamandrian
Orbital characteristics[7]
623.5±10 km
Eccentricity0.31±0.03
2.9651±0.0003 days
Inclination50.1°±1.1° (to primary)
166.2°±3.2° (in EQJ2000)
170.7°±6.1° (in EQJ2000)
113.4°±1.4° (in EQJ2000)
Physical characteristics
Mean diameter
12±3 km (assuming composition of primary)

A 10–15-km-diameter moon, named Skamandrios, was detected orbiting 624 Hektor in 2006 with a semi-major axis of 623.5 km and an orbital period of 2.9651 days (71.162 hours).[14][7] It was confirmed with Keck observations in November 2011,[15] and was then named on 12 March 2017.[16] 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. Its orbit is highly inclined and eccentric, and it is likely that its rotation is chaotic. Marchis et al. (2014) speculate that it was ejected after a low-velocity collision produced the bilobed primary. The newly merged primary could have spun fast enough to be unstable and shed some mass.[7] The dynamics of Skamandrios can be modeled by the restricted four-body problem.[17]

Hektor is the first known trojan with a satellite companion and, so far, one of only four known binary trojan asteroids in the L4 group (the others being 16974 Iphthime, 3548 Eurybates, and 15094 Polymele).

29314 Eurydamas.[18]

Studies

624 Hektor was in a 2003 study of asteroids using the Hubble

AKARI all-sky studies, which reported highly divergent size estimates of 147.4[9] and 231.0 kilometers,[11] respectively. 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.

References

  1. ^ a b c "624 Hektor (1907 XM)". Minor Planet Center. Retrieved 14 June 2018.
  2. ^ a b "Hector". Oxford English Dictionary (Online ed.). Oxford University Press. (Subscription or participating institution membership required.)
  3. ^
    ISBN 978-3-540-00238-3
    .
  4. ^ 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.
  5. ^ "Asteroid 624 Hektor – Nesvorny HCM Asteroid Families V3.0". Small Bodies Data Ferret. Retrieved 24 October 2019.
  6. ^ "List of Jupiter Trojans". Minor Planet Center. 4 October 2017. Retrieved 19 October 2017.
  7. ^
    S2CID 19868908
    .
  8. S2CID 274199
    .
  9. ^
    S2CID 119101711. (online catalog
    )
  10. ^
    S2CID 119226456
    See Table 1.
  11. ^
    doi:10.1093/pasj/63.5.1117. (online, AcuA catalog p. 153
    )
  12. S2CID 119272485
    .
  13. ^ a b c Franck Marchis (November 2005). "Searching and Characterizing Multiple Trojan Asteroids with LGS AO Systems" (PDF) (PDF). Archived from the original (PDF) on 28 July 2020. Retrieved 14 June 2018.
  14. ^ "IAUC 8732: S/2006 (624) 1 (Satellite Discovery)". Central Bureau for Astronomical Telegrams. International Astronomical Union. 21 July 2006. Retrieved 14 June 2018.
  15. ^ @AllPlanets (11 November 2011). "Dome closed, Keck telescope is..." (Tweet) – via Twitter.
  16. ^ "M.P.C. 103967" (PDF). Minor Planet Circular. Minor Planet Center. 12 March 2017. Retrieved 15 October 2020.
  17. S2CID 225526961
    .
  18. ^ "Johnson's Archive - asteroids with satellites". Retrieved 25 October 2020.
  19. ^
    doi:10.1051/0004-6361:20030032
    . Retrieved 14 June 2018.

External links
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