DPS 34th Meeting, October 2002
Session 39. Laboratory Investigations
Oral, Chair(s): J. Allen and R.A. Baragiola, Friday, October 11, 2002, 8:45-10:15 and 10:45-11:15am, Ballroom

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[39.10] Formation of Meteoritic Organic Molecules by Aqueous Alteration of Interstellar Carbonaceous Materials: a Laboratory Model

E. Saperstein, K. M. Arnoult, T. J. Wdowiak, P. A. Gerakines (Astro- and Solar-System Physics Program, Dept. of Physics, Univ. of Alabama at Birmingham)

Polycyclic aromatic hydrocarbons (PAHs) have been proposed as a component of interstellar dust. PAHs have also been positively identified in interplanetary dust particles (IDPs) and in carbonaceous meteorites. Many such meteorites show strong evidence for aqueous alteration of their mineral phases, which can be spatially correlated to the presence of organics. This suggests the possibility that PAHs, incorporated into a meteorite parent body, may have been altered along with neighboring minerals and other constituents in the presence of liquid water.

We present preliminary results of the alteration of a laboratory analog of interstellar carbonaceous dust, produced by processing naphthalene in a hydrogen plasma, by exposing it to water at elevated temperature (100, 150, and 200 C) and pressure in a sealed container for 24 hours. This is a simulation of pressure capping during the accretion of the parent body. The high temperatures chosen here bring water near its critical point, at which it becomes extremely reactive. One sign of this reactivity is seen in the observed color of the aqueously altered product, changing from golden yellow (original color) to black at 200 C. Comparison of the infrared spectra of the original dust analog with those of the aqueously altered product show an oxidation feature at 1700 cm-1, present in all three products but absent in the dust analog. High performance liquid chromatography (HPLC) of the aqueously altered product, refluxed in tetrahydrafuran, shows a variety of low retention peaks (<600 s), absent in the original dust analog.

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Bulletin of the American Astronomical Society, 34, #3< br> © 2002. The American Astronomical Soceity.