Complex organics in meteorites

Area of Science:

• * Astrochemistry
• * Cosmochemistry
• * Organic Geochemistry

Background:

• * Complex macromolecular organic matter is abundant in carbonaceous chondrites, interstellar dust, and comets.
• * This insoluble organic matter is a key component for understanding extraterrestrial organic chemistry.

Purpose of the Study:

• * To investigate the chemical constituents and characteristics of complex organic matter from six CM2 chondrites.
• * To determine the relationship between the complex organic matter and solvent-extractable organic compounds.
• * To assess the influence of thermal history on the complex organic matter.

Main Methods:

• * Isolation of acid-insoluble and solvent-insoluble complex organic matter from six CM2 chondrites.
• * Examination of the organic matter using controlled heating experiments (pyrolysis).
• * Analysis of pyrolyzate products, including identification and quantification of organic compounds.

Main Results:

• * Three chondrites (Yamato-74662, Yamato-791198, Murchison) with solvent-extractable compounds showed a thermally labile organic fraction.
• * Over 130 organic compounds, predominantly aromatic hydrocarbons, were detected in the pyrolyzate of this fraction.
• * The labile fraction appeared around 300°C and disappeared by 600°C, with a peak at 400-500°C.
• * Three other chondrites lacked both extractable compounds and the labile fraction.

Conclusions:

• * The presence or absence of a thermally labile fraction in complex organic matter correlates with the presence of solvent-extractable organic compounds.
• * This correlation suggests that the thermal history of a chondrite influences its organic composition.
• * The study provides insights into the nature and origin of organic matter in meteorites and potentially in the early solar system.