5145 Pholus

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5145 Pholus
Discovery A
Discoverer Spacewatch
(David L. Rabinowitz)
Discovery date January 9, 1992
Alternate
designations
B
1992 AD
Category Centaur, Asteroid
Orbital elements C
Epoch November 26, 2005 (JD 2453700.5)
Eccentricity (e) 0.573
Semi-major axis (a) 3056.379 Gm (20.431 AU)
Perihelion (q) 1306.224 Gm (8.732 AU)
Aphelion (Q) 4806.533 Gm (32.130 AU)
Orbital period (P) 33730.363 d (92.35 a)
Mean orbital speed 6.01 km/s
Inclination (i) 24.685°
Longitude of the
ascending node
(Ω)
119.332°
Argument of
perihelion
(ω)
355.225°
Mean anomaly (M) 55.230°
Physical characteristics D
Dimensions 185±16 km [1]
Mass ~6.6×1018 kg
Density 2.0? g/cm³
Surface gravity ~0.052 m/s²
Escape velocity ~0.098 km/s
Rotation period 9.983 hours
Spectral class (red) B-V=1.19; V-R=0.78 [1]
Absolute magnitude 7.64
Albedo (geometric) 0.046±0.02
Mean surface
temperature
~62 K
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5145 Pholus ("FOE luss") is a Centaur in an eccentric orbit, with a perihelion near the orbit of Saturn and aphelion near the orbit of Neptune. It is believed to have originated as a Kuiper belt object.

It was discovered by David L. Rabinowitz, then of the University of Arizona's Spacewatch Project, and named by him after Pholus, the brother of the mythological Chiron, after which 2060 Chiron was named.

Pholus was the second Centaur type asteroid to be discovered and was quickly found to be quite red in color, for which it has been occasionally nicknamed "Big Red". The color has been speculated to be due to organic compounds on its surface. (Wilson, et al., 1994) Unlike the first Centaur, 2060 Chiron, Pholus has shown no signs of cometary activity.

The diameter of Pholus is estimated to be 185±16 km [2].

[edit] References

  1. ^ Tegler, Stephen C. (2006-01-26). Kuiper Belt Object Magnitudes and Surface Colors. Retrieved on 2006-11-05.
  • Wilson PD, Sagan C, Thompson WR (1994). "The organic surface of 5145 Pholus: constraints set by scattering theory". Icarus 107: 288-303. PMID 11539180


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For a complete listing, see: List of asteroids. See also Pronunciation of asteroid names and Meanings of asteroid names.