The Composition of Centaur 5145 Pholus

D. P. Cruikshank, T. L. Roush, M. J. Bartholomew, T. R. Geballe, Y. J. Pendleton, S. M. White, J. F. Bell, J. K. Davies, T. C. Owen, C. De Bergh, D. J. Tholen, M. P. Bernstein, Robert H. Brown, K. A. Tryka, C. M. Dalle Ore

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Abstract

We present a new spectrum of the Centaur object 5145 Pholus between 1.15 and 2.4 μm. We model this, and the previously published (0.4- to 1.0-μm) spectrum, using Hapke scattering theory. Seen in absorption are the 2.04-μm band of H2O ice and a strong band at 2.27 μm, interpreted as frozen methanol and/or a photolytic product of methanol having small molecular weight. The presence of small molecules is indicative of a chemically primitive surface, since heating and other processes remove the light hydrocarbons in favor of macromolecular carbon of the kind found in carbonaceous meteorites. The unusually red slope of Pholus' spectrum is matched by fine grains of a refractory organic solid (tholin), as found previously by M. Hoffmannet al. (1993,J. Geophys. Res.98, 7403-7407) and P. D. Wilsonet al.(1994,Icarus107, 288-303). Olivine (which we model with Fo 82) also appears to be present on Pholus. We present a five-component model for the composite spectrum of all spectroscopic and photometric data available for 5145 Pholus and conclude that this is a primitive object which has not yet been substantially processed by solar heat. The properties of Pholus are those of the nucleus of a large comet that has never been active.

Original languageEnglish (US)
Pages (from-to)389-407
Number of pages19
JournalIcarus
Volume135
Issue number2
DOIs
StatePublished - Oct 1998

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methanol
methyl alcohol
carbonaceous meteorites
organic solids
refractories
comets
olivine
meteorite
comet
molecular weight
ice
hydrocarbons
scattering
hydrocarbon
slopes
heating
heat
nuclei
composite materials
carbon

ASJC Scopus subject areas

  • Space and Planetary Science
  • Astronomy and Astrophysics

Cite this

Cruikshank, D. P., Roush, T. L., Bartholomew, M. J., Geballe, T. R., Pendleton, Y. J., White, S. M., ... Dalle Ore, C. M. (1998). The Composition of Centaur 5145 Pholus. Icarus, 135(2), 389-407. https://doi.org/10.1006/icar.1998.5997

The Composition of Centaur 5145 Pholus. / Cruikshank, D. P.; Roush, T. L.; Bartholomew, M. J.; Geballe, T. R.; Pendleton, Y. J.; White, S. M.; Bell, J. F.; Davies, J. K.; Owen, T. C.; De Bergh, C.; Tholen, D. J.; Bernstein, M. P.; Brown, Robert H.; Tryka, K. A.; Dalle Ore, C. M.

In: Icarus, Vol. 135, No. 2, 10.1998, p. 389-407.

Research output: Contribution to journalArticle

Cruikshank, DP, Roush, TL, Bartholomew, MJ, Geballe, TR, Pendleton, YJ, White, SM, Bell, JF, Davies, JK, Owen, TC, De Bergh, C, Tholen, DJ, Bernstein, MP, Brown, RH, Tryka, KA & Dalle Ore, CM 1998, 'The Composition of Centaur 5145 Pholus', Icarus, vol. 135, no. 2, pp. 389-407. https://doi.org/10.1006/icar.1998.5997
Cruikshank DP, Roush TL, Bartholomew MJ, Geballe TR, Pendleton YJ, White SM et al. The Composition of Centaur 5145 Pholus. Icarus. 1998 Oct;135(2):389-407. https://doi.org/10.1006/icar.1998.5997
Cruikshank, D. P. ; Roush, T. L. ; Bartholomew, M. J. ; Geballe, T. R. ; Pendleton, Y. J. ; White, S. M. ; Bell, J. F. ; Davies, J. K. ; Owen, T. C. ; De Bergh, C. ; Tholen, D. J. ; Bernstein, M. P. ; Brown, Robert H. ; Tryka, K. A. ; Dalle Ore, C. M. / The Composition of Centaur 5145 Pholus. In: Icarus. 1998 ; Vol. 135, No. 2. pp. 389-407.
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