论文标题
N含N型复合物有机物朝向高质量质体：恒定比率指向在大质量范围内类似的固有条件下形成的比率
N-bearing complex organics toward high-mass protostars: Constant ratios pointing to formation in similar pre-stellar conditions across a large mass range
论文作者
论文摘要
到目前为止，尚未对大量高质量原始恒星样本进行COM的统计研究。我们的目标是研究六种含有六种含物的物种：CH $ _3 $ CN，HNCO，NH $ _2 $ CHO，C $ _2 $ H $ _5 $ _5 $ CN，C $ _2 $ _2 $ H $ _3 $ _3 $ CN和CH $ _3 $ _3 $ nh $ _2 $ nh $ _2 $ _2 $ _2 $ _2 $ s High-Mass Protostars。从Almagal调查中，选择了37个最富含线的热分子核。接下来，我们适合它们的光谱，除了$ _3 $ oh之外，还可以找到上述N含物种的柱密度和激发温度。我们（暂时）检测$ _3 $ nh $ _2 $ in $ \ sim32％$的来源。在比较它们的激发温度时，我们会发现三组物种：热（NH $ _2 $ CHO; TEX> 250 K），温暖（C $ _2 $ H $ _3 $ _3 $ CN，Hn $^{13} $ CO和CH $ _ {3} {3}^{13}^{13}^{13} $ cn; 100 k <dex <250 K）$ ch $ ch $ ch $ _3 $ _3 $ hhh，以及; <100 k）。这种温度隔离反映了其升华温度中看到的趋势，并验证了质体周围com的洋葱状结构的概念。此外，这里研究的分子在低质量和高质量原恒星上显示出恒定的色谱柱密度比，散射小于均值$ \ sim3 $围绕平均值。恒定的柱密度比指向COM或其前体的共同形成环境，这很可能是在固有冰中。比率均衡的散射虽然很小，但取决于所考虑的物种。这种扩展可以具有物理起源（源结构，线路或尘埃深度）或化学物质。甲酰胺最容易遭受物理效应，因为它追踪了最接近原恒星的区域，而对于其他物种来说，这种影响很小。假设在固有冰中形成所有分子，则可以通过遗产前云的生命或物理条件的差异来解释散射变化。如果遗前的寿命是主要因素，则对于低质量和高质量原始恒星应该相似。
No statistical study of COMs toward a large sample of high-mass protostars with ALMA has been carried out so far. We aim to study six N-bearing species: CH$_3$CN, HNCO, NH$_2$CHO, C$_2$H$_5$CN, C$_2$H$_3$CN and CH$_3$NH$_2$ in a large sample of high-mass protostars. From the ALMAGAL survey, 37 of the most line-rich hot molecular cores are selected. Next, we fit their spectra and find column densities and excitation temperatures of the above N-bearing species, in addition to CH$_3$OH. We (tentatively) detect CH$_3$NH$_2$ in $\sim32%$ of the sources. We find three groups of species when comparing their excitation temperatures: hot (NH$_2$CHO; Tex > 250 K), warm (C$_2$H$_3$CN, HN$^{13}$CO and CH$_{3}^{13}$CN; 100 K < Tex < 250 K) and cold species (CH$_3$OH and CH$_3$NH$_2$; Tex < 100 K). This temperature segregation reflects the trend seen in their sublimation temperatures and validates the idea of onion-like structure of COMs around protostars. Moreover, the molecules studied here show constant column density ratios across low- and high-mass protostars with scatter less than a factor $\sim3$ around the mean. The constant column density ratios point to a common formation environment of COMs or their precursors, most likely in the pre-stellar ices. The scatter around the mean of the ratios, although small, varies depending on the species considered. This spread can either have a physical origin (source structure, line or dust optical depth) or a chemical one. Formamide is most prone to the physical effects as it is tracing the closest regions to the protostars, whereas such effects are small for other species. Assuming that all molecules form in the pre-stellar ices, the scatter variations could be explained by differences in lifetimes or physical conditions of the pre-stellar clouds. If the pre-stellar lifetimes are the main factor, they should be similar for low- and high-mass protostars.
