SURVEY OF CH3NH2 AND ITS FORMATION PROCESS

We present the observational result of a precursor of glycine, methylamine (CH3NH2), together with methanol (CH3 OH) and methanimine (CH2 NH) towards the high-mass star-forming regions NGC6334I, G10.47+0.03, G31.41+0.3, and W51 e1/e2 using ALMA. The molecular abundances toward these sources were derived using the CASSIS spectrum analyser and compared with our state-of-the-art 3-phase chemical model NAUTILUS. We found that the observed abundance ratio of CH3NH2/CH3OH is between 0.008 and 1.0 for all the sources, except for NGC6334I MM3, where a ratio less than 0.002 is found. This may be due to the later evolutionary stage than the other cores. We also found that the observed CH3NH2/CH3OH ratio agrees well with the three-phase chemical model NAUTILUS, which includes the formation of CH3NH2 on the grain surface via a series of hydrogenation processes of HCN. This result clearly shows the importance of hydrogenation processes to form CH3NH2.

我们利用阿塔卡马大型毫米波/亚毫米波阵列（ALMA），针对大质量恒星形成区NGC6334I、G10.47+0.03、G31.41+0.3及W51 e1/e2，呈现了甘氨酸前体甲胺（CH3NH2）、甲醇（CH3OH）与甲亚胺（CH2NH）的观测结果。这些源的分子丰度通过CASSIS光谱分析仪推导得出，并与我们最先进的三相化学模型NAUTILUS的结果进行了对比。我们发现，除NGC6334I MM3源的比值低于0.002外，其余所有源的CH3NH2/CH3OH观测丰度比介于0.008至1.0之间。这可能归因于该核心区域的演化阶段晚于其他核心。我们还发现，观测到的CH3NH2/CH3OH比值与三相化学模型NAUTILUS的结果高度一致，该模型包含了氰化氢（HCN）通过一系列氢化过程在尘埃表面形成CH3NH2的机制。这一结果明确表明了氢化过程在CH3NH2形成中的重要性。