The composition of Centaur 5145 Pholus

被引:219
作者
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
机构
[1] NASA, Ames Res Ctr, Moffett Field, CA 94035 USA
[2] Sterling Software, Moffett Field, CA 94035 USA
[3] Joint Astron Ctr, Hilo, HI 96720 USA
[4] Cornell Univ, CRSR, Ithaca, NY 14853 USA
[5] Joint Astron Ctr, Hilo, HI 96720 USA
[6] Inst Astron, Honolulu, HI 96822 USA
[7] Observ Paris, F-92195 Meudon, France
[8] SETI Inst, Moffett Field, CA 94035 USA
[9] Univ Arizona, Lunar & Planetary Lab, Tucson, AZ 85721 USA
[10] No Arizona Univ, Dept Phys, Flagstaff, AZ 86011 USA
基金
美国国家航空航天局;
关键词
asteroids; composition; comets; ices; centaurs; prebiotic chemistry;
D O I
10.1006/icar.1998.5997
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
We present a new spectrum of the Centaur object 5145 Pholus between 1.15 and 2.4 Gem. We model this, and the previously published (0.4- to 1.0-mu m) spectrum, using Hapke scattering theory. Seen in absorption are the 2.04-mu m band of H(2)O ice and a strong band at 2.27 mu m, 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. Hoffmann et al, (1993, J. Geophys. Res. 98, 7403-7407) and P. D. Wilson et al. (1994, Icarus 107, 288-303). Olivine (which we model with Fo 82) also appears to be present on Pholus. We present a live-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 hips 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. (C) 1998 Academic Press.
引用
收藏
页码:389 / 407
页数:19
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