DETECTABILITY OF GLYCINE IN SOLAR-TYPE SYSTEM PRECURSORS
DETECTABILITY OF GLYCINE IN SOLAR-TYPE SYSTEM PRECURSORS
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DOI：
10.1088/2041-8205/787/2/l33
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发表时间：
2014-04
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影响因子：
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通讯作者：
I. Jímenez-Serra;L. Testi;P. Caselli;S. Viti
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作者：
I. Jímenez-Serra;L. Testi;P. Caselli;S. Viti
甘氨酸（NH2CH2COOH）是与生命相关的最简单的氨基酸。它在星际介质中的探测是理解前生物分子形成机制及其随后传递到行星系统的关键。甘氨酸已被广泛搜索到热分子核心，尽管这些研究没有产生任何确定的检测结果。与热核心相反，低质量星星形成区域，特别是以冷的前恒星核心为代表的最早阶段，可能更适合于检测甘氨酸，也更适合于研究年轻太阳系类似物中的前生物化学。我们提出了一维球对称的辐射传输计算的甘氨酸发射预计将产生的低质量的恒星前的核心L1544。最近有报道称，水蒸气正朝着这个核心移动，这表明L1544中的一小部分（约0.5%）的颗粒地幔已经注入到气相中。假设甘氨酸在L1544中与水一起光解吸，并考虑冰上甘氨酸相对于水的固体丰度为1010 −4，我们的计算表明，67 GHz和80 GHz之间的几条甘氨酸谱线的峰值强度大于10 mK。这些结果首次表明，甘氨酸可以在L1544等冷物体中达到可检测的水平。这就有可能在太阳型系统形成的最冷和最早阶段，利用诸如阿尔马的波段2接收器等近期仪器，探测甘氨酸和其他前生物物种。
Glycine (NH2CH2COOH) is the simplest amino acid relevant to life. Its detection in the interstellar medium is key to understanding the formation mechanisms of pre-biotic molecules and their subsequent delivery onto planetary systems. Glycine has been extensively searched for toward hot molecular cores, although these studies did not yield any firm detection. In contrast to hot cores, low-mass star forming regions, in particular their earliest stages represented by cold pre-stellar cores, may be better suited for the detection of glycine as well as more relevant to the study of pre-biotic chemistry in young solar system analogs. We present one-dimensional spherically symmetric radiative transfer calculations of the glycine emission expected to arise from the low-mass pre-stellar core L1544. Water vapor has recently been reported toward this core, indicating that a small fraction of the grain mantles in L1544 (∼0.5%) has been injected into the gas phase. Assuming that glycine is photo-desorbed together with water in L1544, and considering a solid abundance of glycine on ices of ∼10−4 with respect to water, our calculations reveal that several glycine lines between 67 GHz and 80 GHz have peak intensities larger than 10 mK. These results show for the first time that glycine could reach detectable levels in cold objects such as L1544. This opens up the possibility of detecting glycine, and other pre-biotic species, at the coldest and earliest stages in the formation of solar-type systems with near-future instrumentation such as the Band 2 receivers of ALMA.