5145 Pholus

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5145 Pholus
Discovery[1]
Discovered by
Perihelion
8.7531 AU
20.348 AU
Eccentricity0.5698
91.79 yr (33,526 d)
117.26°
0° 0m 38.52s / day
Inclination24.617°
119.44°
354.77°
Jupiter MOID3.495 AU
Saturn MOID0.34961[1]
TJupiter3.21
Physical characteristics
Dimensions310 km × 160 km × 150 km[8]
Mean diameter
Synodic rotation period
9.980 h[8]
  • 0.04 (assumed)[8]
  • 0.044±0.013[5]
  • 0.155±0.076[9]
21.62[13]
16.3 (Perihelic opposition)

5145 Pholus

rotation period of 9.98 hours.[18] It was named after the centaur Pholus from Greek mythology.[1]

Orbit and classification

Orbital diagram of 5145 Pholus

Pholus was the second

trans-Neptunian populations of the Solar System – that is, beyond Jupiter's and within Neptune's orbit – which behave with characteristics of both asteroids and comets
.

It orbits the Sun at a distance of 8.8–31.9 

Neptune-crosser, crossing the orbits of these giant planets at a mean distance of 9.6, 11.9, and 30.1 AU from the Sun, respectively. Pholus has not come within one astronomical unit of a planet since 764 BC, and will not until 5290.[20] It is believed that it originated in the Kuiper belt
.

Discovery and naming

Pholus was discovered by

Charles Kowal in 1977. In 1993, while with the Spacewatch program, David Rabinowitz went on to discover another centaur, 7066 Nessus
.

This

M.P.C. 20523).[21]

A symbol derived from that for

φ.[23]

Physical characteristics

Spectral type and color

After its discovery, Pholus was quickly found to be very red in color. The color has been speculated to be due to organic compounds on its surface.

Tholen taxonomic scheme.[5]

The object has been classified by astronomers as RR and RR-U type, respectively.[11][12] Polarimetric observations with ESO's Very Large Telescope in 2007 and 2008, revealed noticeable negative polarization at certain phase angles, distinctly different from that of trans-Neptunian objects. Pholus appears to have a rather homogeneous surface with a small amount of water frost on its darker regions.[12]

The surface composition of Pholus has been estimated from its reflectance spectrum using two spatially segregated components:[24] dark amorphous carbon and an intimate mixture of water ice, methanol ice, olivine grains, and complex organic compounds (tholins). The carbon black component was used to match the low albedo of the object. Unlike Chiron, Pholus has shown no signs of cometary activity.

Diameter and albedo

Diameter calculations range from 99 to 190 kilometers with a corresponding albedo between 0.155 and 0.04.[6][8][9][18][10]

According to the

Mount Graham Observatory, Arizona, determined an elongated shape, 310 km × 160 km × 150 km, with a mean diameter of 190 kilometers, based on a low albedo of 0.04.[8] Johnston's archive lists a diameter of 107 km with an albedo of 0.126,[6] and Collaborative Asteroid Lightcurve Link assumes a standard albedo of a carbonaceous body of 0.057 and derives a diameter of 165 km based on an absolute magnitude of 7.64.[18]

Rotation period

In March 2005, a rotational

U=3/3/3).[25][26][27]

See also

References

  1. ^ a b c d e f g h "5145 Pholus (1992 AD)". Minor Planet Center. Retrieved 26 November 2018.
  2. ^ a b "IAUC 5434: 1992 AD". Central Bureau for Astronomical Telegrams. 23 January 1992. Retrieved 26 November 2018.
  3. ^ Noah Webster (1884) A Practical Dictionary of the English Language
  4. ^
    ISBN 978-3-540-00238-3
    .
  5. ^ a b c d e f g h i "JPL Small-Body Database Browser: 5145 Pholus (1992 AD)" (2009-04-18 last obs.). Jet Propulsion Laboratory. Retrieved 26 November 2018.
  6. ^ a b c d Johnston, Wm. Robert (7 October 2018). "List of Known Trans-Neptunian Objects". Johnston's Archive. Retrieved 26 November 2018.
  7. ^ "Asteroid 5145 Pholus". Small Bodies Data Ferret. Retrieved 26 November 2018.
  8. ^
    doi:10.1016/j.icarus.2004.12.011
    .
  9. ^
    S2CID 119177446
    .
  10. ^
    Bibcode:1996ASPC..107...97D
    .
  11. ^
    S2CID 55619450
    .
  12. ^
    doi:10.1016/j.icarus.2014.12.004
    .
  13. ^ "AstDys (7066) Nessus Ephemerides". AstDyS-2, Asteroids – Dynamic Site; Department of Mathematics, University of Pisa, Italy. Retrieved 4 July 2021.
  14. S2CID 55876118
    .
  15. S2CID 4313184
    .
  16. doi:10.1016/j.icarus.2005.06.016
    .
  17. doi:10.1006/icar.1998.5931
    .
  18. ^ a b c "LCDB Data for (5145) Pholus". Asteroid Lightcurve Database (LCDB). Retrieved 16 November 2016.
  19. ^
    PMID 11539180
    .
  20. ^ "Fifty clones of Centaur 5145 Pholus all passing within ~100Gm of Neptune on 5290-07-07". Retrieved 23 April 2009. (Solex 10)
  21. ^ "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 26 November 2018.
  22. ^ Miller, Kirk; Stein, Zane (26 August 2021). "Comment on U+26B7 CHIRON" (PDF). L2/21-225.
  23. ^ David Faulks, L2/16-080R
  24. S2CID 55496203
    .
  25. Bibcode:1992LIACo..30..203H
    .
  26. doi:10.1006/icar.2001.6656
    .
  27. doi:10.1016/0019-1035(92)90101-C
    .

External links
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