5:15 PM - 6:30 PM
[PPS12-P12] Evaluation of gamma-ray effects for formation of amino acid precursors in the Solar System small bodies
Keywords:Meteorites, Asteroids, Organic matter, Gamma ray
Amino acids including glycine, alanine and beta-alanine were detected from the most of the irradiated and heated samples after acids hydrolysis, but little or no amino acids were detected from the solutions before acid hydrolysis. The yields of amino acids from the solutions after heating experiments were larger than these after gamma-ray irradiation with the presence of Ca(OH)2, but the amino acid yields from heating were smaller than these of gamma-ray irradiation without the presence of Ca(OH)2. These results indicate that Ca(OH)2 was act as a catalyst to produce amino acid precursors in the heating experiments but was not in the case of gamma-ray irradiation. The solutions after heating had smaller alanine/glycine ratios than the solutions after irradiation, suggesting that heating and irradiation have different reaction mechanisms.
Insoluble fraction was only observed in the product from heating at 150 °C with ammonia. IR spectra of the insoluble fraction and soluble fraction (both dried on CaF2 plates) revealed that soluble fraction contained amines and amides, but these bands were not significant in the IR spectra of the insoluble fraction. It suggest that the amino acids are produced from precursors containing amide bonds after braking these bonds by acid hydrolysis.
 G. D. Cody et al., PNAS, 108, 19171-19176 (2011).
 Y. Kebukawa et al., Astrophysical J., 771, 19 (2013).