[P-PS08] 太陽系物質進化

[PPS08-09] Similarities in the relative abundance of amino acids and imidazole of heated cometary volatiles to primitive carbonaceous chondrites

*平川 祐太¹、古川 善博¹ (1.東北大学)

キーワード：可溶性有機物、彗星、水質変質、イミダゾール、アミノ酸

Carbonaceous chondrites contain various organic molecules including amino acids and N-heterocycles. Identifying their origins is one of the fundamental steps for understanding the evolution of the early solar system and the delivery of biotic molecules to the prebiotic Earth. Imidazole, one of the most abundant N-heterocycles in primitive carbonaceous chondrites, was proposed to be formed by the parent body aqueous processes because aqueous reactions between aldehydes and ammonia can form imidazole. However, the synthesis of imidazole from potential parent body organics simulating parent body processes has not been well investigated. We conducted hydrothermal experiments simulating the parent body aqueous process using a mixture of potential parent body organics. The aqueous solution containing CH₂O, CH₃OH, NH₃, KCN, CH₃CHO, CH₂OHCHO, and KOCN was heated at 90-150℃ for 1-90 days. These starting materials were referred to as molecules found in cometary ice to simulate primitive molecules in asteroids before the aqueous alteration. The products were analyzed qualitatively and quantitatively to find N-heterocycles including imidazole.
Various amino acids and N-heterocycles including imidazole were detected. The relative abundances of amino acids and imidazole showed a good agreement with carbonaceous chondrites. This supports that imidazole could be formed by the parent body aqueous process in carbonaceous chondrites.