617 Patroclus

Source: Wikipedia, the free encyclopedia.

617 Patroclus
V–I = 0.830±0.020[20]
8.18[4][11][12][13][5]

617 Patroclus (/pəˈtroʊkləs/ pə-TROH-kləs) is a large binary Jupiter trojan asteroid. It is a dark D-type asteroid and a slow rotator, due to the 103-hour orbital period of its two components. It is one of five Jupiter trojan asteroids targeted by the Lucy space probe, and is scheduled for a flyby in 2033.

Patroclus was discovered on 17 October 1906, by astronomer

Trojan camp named after a Greek figure, as the convention of naming one 'camp' after Greek figures of the Trojan War and the other after Trojan figures had not yet been established.[3]

Patroclus was long thought to be one of the largest Jupiter trojans, with a diameter on the order of 150 km. However, in 2001 it was discovered to be a binary asteroid of two similarly sized objects. The name Patroclus is now assigned to the larger component, some 110–115 km in diameter, while the secondary, slightly smaller at 100–105 km in diameter, has been named Menoetius (/mɪˈniːʃəs/ mə-NEE-shəs).[a] This was the first discovery of a binary trojan asteroid.[9]

Orbit

Patroclus orbits in Jupiter's trailing

Trojan camp after one of the sides in the legendary Trojan War (the other node, at the L4 point
, is called the "Greek camp").

It orbits the Sun at a distance of 4.5–5.9 AU once every 11 years and 11 months (4,353 days). Its orbit has an eccentricity of 0.14 and an inclination of 22° with respect to the ecliptic.[4] The asteroid's observation arc begins at the discovering Heidelberg Observatory in November 1906, about 3 weeks after its official discovery observation.[1]

Binary system

Hubble images of Patroclus and Menoetius orbiting each other, from May to June 2017
Artist's conception of Patroclus and Menoetius orbiting around their center of mass, occasionally eclipsing one another
Artist's impression of the Patroclus-Menoetius binary system
Menoetius
Plot of the results of the multi-chord stellar occultation by 617 Patroclus and Menoetius
Discovery
Discovery date2001
Designations
Pronunciation/mɪˈniːʃəs/
Named after
Menoetius (Greek mythology)
AdjectivesMenoetian /mɪˈniːʃən/[21])
Orbital characteristics
680±20 km[9]
664.6 km[10]
102.8 h
Satellite ofPatroclus
Physical characteristics
Dimensions117 km × 108 km × 90 km[10]
Mean diameter
104±3 km[10]

In 2001, it was discovered that Patroclus is a

Keck Laser guide star adaptive optics system were reported.[24]

It was estimated[25] that the two components orbit around their center of mass in 4.283±0.004 days at a distance of 680±20 km in a roughly circular orbit.[9] Combining these observations with thermal measurements taken in 2000, the sizes of the components of the system were estimated at 106 km and 98 km, with an equivalent whole-system diameter of 145 km,[9] refined by later measurements from the Keck Observatory to approximately 122 km and 112 km for each partner,[26] and a co-orbital period of 103.5±0.3 hours (4.3125±0.0125 days).[24][18]

On 21 October 2013, both bodies occulted a magnitude 8.8 star as observed by a team of 41 observers stationed across the USA. Observation data put the orbital distance at the time of 664.6 km (with an unstated uncertainty), and give a size for the slightly larger component, which retains the name Patroclus with overall volume equivalent to a 113±3 km–diameter sphere, with the smaller component now named Menoetius with a volume equivalent to a 104±3 km–diameter sphere.

Physical characteristics

Lightcurves

Since 1989, several rotational

U=2/3/).[15][16][17][18] A low brightness variation typically indicates that a body has a nearly spheroidal shape. Its long rotation period makes it a slow rotator
.

Diameter and albedo

According to the surveys carried out by the Infrared Astronomical Satellite

albedo of 0.047.[11][13] The Collaborative Asteroid Lightcurve Link adopts the results obtained by IRAS, that is, an albedo of 0.0471 and a diameter of 140.92 kilometers based on an absolute magnitude of 8.19.[5]

Composition

Recent evidence suggests that the objects are icy like

Tholen classification, Patroclus is a dark P-type asteroid.[5]

Because the density of the components (0.88 g/cm3) is less than water and about one third that of rock, it was suggested that the Patroclus system, previously thought to be a pair of rocky asteroids, is more similar to a comet in composition.[24] It is suspected that many Jupiter trojans are in fact small planetesimals captured in the Lagrange point of the Jupiter–Sun system during the migration of the giant planets 3.9 billion years ago. This scenario was proposed by A. Morbidelli and colleagues in a series of articles published in May 2005 in Nature.[27]

Exploration

Animation of Lucy's trajectory around Sun
  Lucy ·    Sun ·    Earth ·    52246 Donaldjohanson  ·   3548 Eurybates ·    21900 Orus ·    617 Patroclus
Artist's impression of the Lucy spacecraft flying past the Patroclus-Menoetius system

The Patroclus–Menoetius system is a scheduled target for

Jupiter trojans.[28]

Name

See also: Patroclus § Pronunciation

This

H 65).[3]

In Greek and thus in Latin, Patroclus has all short vowels. Thus the expected English pronunciation would be with stress on the 'a', */ˈpætrəkləs/. However, Alexander Pope shifted the stress to the first 'o', /pəˈtroʊkləs/, a convention from Latin poetry,[b] for metrical convenience in his verse translation of Homer, and this irregular pronunciation has become established in English.[2]

The satellite Menoetius (

provisional designation
S/2001 (617) 1.

Patroclus and Menoetius are the only objects in the Trojan camp to be named after Greek rather than Trojan characters. The naming conventions for the Jupiter trojans were not adopted until after Patroclus was named (similarly, the asteroid

Greek camp
).

Notes

  1. asteroid occultation. Other observations gave a combined diameter of 140 kilometers. Summary figures for (617) Patroclus at the LCDB
    .
  2. ^ This poetic exception to normal Latin stress assignment is used for metrical convenience in Latin, and Pope retained it in his English translation. It is available when the final syllable starts with a sequence of two consonants, the first a plosive (a b c d g p or t) and the second a liquid (an l or an r).

References

  1. ^ a b c d "617 Patroclus (1906 VY)". Minor Planet Center. Retrieved 13 June 2018.
  2. ^ a b "Patroclus". Dictionary.com Unabridged (Online). n.d.
  3. ^
    ISBN 978-3-540-00238-3
    .
  4. ^ a b c d "JPL Small-Body Database Browser: 617 Patroclus (1906 VY)" (2017-06-14 last obs.). Jet Propulsion Laboratory. Retrieved 13 June 2018.
  5. ^ a b c d "LCDB Data for (617) Patroclus". Asteroid Lightcurve Database (LCDB). Retrieved 11 July 2017.
  6. ^ "List of Jupiter Trojans". Minor Planet Center. 20 August 2016. Retrieved 11 July 2017.
  7. ^ a b "Asteroid (617) Patroclus – Proper elements". AstDyS-2, Asteroids – Dynamic Site. Retrieved 13 June 2018.
  8. ^ Riggs (1972) The Christian poet in Paradise lost
  9. ^ a b c d e f g Johnston, Wm. Robert (21 September 2014). "(617) Patroclus and Menoetius". johnstonsarchive.net. Retrieved 11 July 2017.
  10. ^
    S2CID 121095409
    . Retrieved 11 July 2017.
  11. ^
    S2CID 119101711. (online catalog
    )
  12. ^
    doi:10.1093/pasj/63.5.1117. (online, AcuA catalog p. 153
    )
  13. ^
    Bibcode:2004PDSS...12.....T
    . Retrieved 13 June 2018.
  14. ^
    S2CID 119226456
    . See Table 1.
  15. ^
    S2CID 4416425
    . Retrieved 11 July 2017.
  16. ^ a b Behrend, Raoul. "Asteroids and comets rotation curves – (617) Patroclus". Geneva Observatory. Retrieved 11 July 2017.
  17. ^
    S2CID 118634843
    .
  18. ^
    ISSN 1052-8091
    . Retrieved 11 July 2017.
  19. ^ a b c d "Asteroid 617 Patroclus". Small Bodies Data Ferret. Retrieved 13 June 2018.
  20. ^
    doi:10.1016/j.icarus.2016.01.026
    .
  21. ^ Redfield (1994) Nature and culture in the Iliad: the tragedy of Hector
  22. ^ Merline, W. J. (2001), IAUC 7741: 2001fc; S/2001 (617) 1; C/2001 T1, C/2001 T2
  23. ^ "Satellites and Companions of Minor Planets". IAU / CBAT. 17 September 2009. Archived from the original on 21 January 2011. Retrieved 25 January 2011.
  24. ^
    S2CID 4416425
    .
  25. ^ Sanders, Robert (2006), Binary asteroid in Jupiter's orbit may be icy comet from solar system's infancy, University of California, Berkeley
  26. ^ Sanders, Robert. "Trojan Binary Asteroid – Patroclus & Menoetius". UC Berkeley. Retrieved 4 October 2017.
  27. S2CID 4373366
    .
  28. ^ Dreier, Casey; Lakdawalla, Emily (30 September 2015). "NASA announces five Discovery proposals selected for further study". The Planetary Society. Retrieved 1 October 2015.

External links

Retrieved from "https://en.wikipedia.org/w/index.php?title=617_Patroclus&oldid=1204819311"