论文标题
外部星系中碳分馏的化学研究
A chemical study of carbon fractionation in external galaxies
论文作者
论文摘要
在星际中，碳的存在于两个稳定的同位素的形式，$^{12} $ c和$^{13} $ c，它们的比例很好地指示了星系中的核合成。但是，化学分级可能会显着改变该比率，实际上，发现同一星系内碳分馏的观察结果因物种而异。在本文中，我们从理论上研究了所选丰富碳种类的碳分馏，以确定可能导致外部星系中$^{12} $ C/$^{13} $ c比率扩散的条件。我们发现，碳分馏对我们研究的几乎所有物理状况都是敏感的，除了CO以外，所有物种的时间都有很大的变化，并且显示出跨物种的明显差异。最后，我们在$^{12} $ c/$^{13} $ c比率的少数观察结果中讨论了我们的理论结果。
In the interstellar medium carbon exists in the form of two stable isotopes $^{12}$C and $^{13}$C and their ratio is a good indicator of nucleosynthesis in galaxies. However, chemical fractionation can potentially significantly alter this ratio and in fact observations of carbon fractionation within the same galaxy has been found to vary from species to species. In this paper we theoretically investigate the carbon fractionation for selected abundant carbon-bearing species in order to determine the conditions that may lead to a spread of the $^{12}$C/$^{13}$C ratio in external galaxies. We find that carbon fractionation is sensitive to almost all the physical conditions we investigated, it strongly varies with time for all species but CO, and shows pronounced differences across species. Finally we discuss our theoretical results in the context of the few observations of the $^{12}$C/$^{13}$C ratio in both local and higher redshift galaxies.
