High-temperature Ionization-induced Synthesis of Biologically Relevant Molecules in the Protosolar Nebula
High-temperature Ionization-induced Synthesis of Biologically Relevant Molecules in the Protosolar Nebula
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DOI：
10.3847/1538-4357/aabe7a
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发表时间：
2018-06-01
影响因子：
4.9
通讯作者：
Marty, Bernard
中科院分区：
文献类型：
--
作者：
Bekaert, David V.;Derenne, Sylvie;Marty, Bernard
生物相关分子（以下简称生物分子）已在地外样本中普遍观察到，但其在太空中合成的机制尚不清楚。虽然电子驱动产生的有机固体气体混合物让人想起原太阳星云的光球（PSN，即CO-N-2-H-2主导）成功地再现了球粒质不溶性有机物的关键特征（例如，球粒质惰性气体的元素和同位素特征），但有机物质的分子多样性从未被研究过。在这里，我们报告了在温度= 800 K的PSN辐照气相的典型条件下，可以合成陨石和彗星中检测到的大量生物分子。我们的研究结果表明，在光球内产生的有机物质（包括生物分子）可能通过湍流扩散广泛分散在原行星盘中，这为有机陨石前体的分布提供了一种机制，这种机制先于任何热/光处理和随后的次级母体过程的修饰。利用湍流盘中尘埃传输的数值模型，我们提出在盘的光球中产生的有机物质可能与小尘埃颗粒有关，这些小尘埃颗粒与盘内气体的运动相耦合，因此优先上升到盘的上层，在那里发生有机合成。
Biologically relevant molecules (hereafter biomolecules) have been commonly observed in extraterrestrial samples, but the mechanisms accounting for their synthesis in space are not well understood. While electron-driven production of organic solids from gas mixtures reminiscent of the photosphere of the protosolar nebula (PSN; i.e., dominated by CO-N-2-H-2) successfully reproduced key specific features of the chondritic insoluble organic matter (e.g., elementary and isotopic signatures of chondritic noble gases), the molecular diversity of organic materials has never been investigated. Here, we report that a large range of biomolecules detected in meteorites and comets can be synthesized under conditions typical of the irradiated gas phase of the PSN at temperatures = 800 K. Our results suggest that organic materials-including biomolecules-produced within the photosphere would have been widely dispersed in the protoplanetary disk through turbulent diffusion, providing a mechanism for the distribution of organic meteoritic precursors prior to any thermal/photoprocessing and subsequent modification by secondary parent body processes. Using a numerical model of dust transport in a turbulent disk, we propose that organic materials produced in the photosphere of the disk would likely be associated with small dust particles, which are coupled to the motion of gas within the disk and therefore preferentially lofted into the upper layers of the disk where organosynthesis occurs.