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Paper: Establishing the Synthetic Contingencies for Life: Following the Carbon from AGB Stars to Planetary Surfaces
Volume: 420, Bioastronomy 2007: Molecules, Microbes and Extraterrestrial Life
Page: 59
Authors: Ziurys, L. M.; Halfen, D. T.; Woolf, N. J.
Abstract: The biochemistry of living systems is remarkably selective, utilizing certain chemical compounds and not other, closely related molecules. This selectivity might be a result of interstellar chemistry. Organic synthesis in space is remarkably active. It begins with the carbon-rich chemistry of circumstellar envelopes, which appears to survive in part as these objects evolve into planetary nebula and then into diffuse clouds. Diffuse clouds subsequently collapse into dense clouds, carrying along the chemical imprint of previous syntheses. This cycling of molecular gas provides dense clouds with C-rich starting material, which accelerates organic chemistry in these objects. The low temperature environment of interstellar space restricts available chemical pathways, resulting in molecule formation that is non-combinatorial. Comets, meteorites, and perhaps interplanetary dust particles then bring these select organic compounds to planetary surfaces. Thus, the ‚Äúsynthetic contingencies‚ÄĚ that led to life on Earth may have been established by interstellar chemistry.
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