热岩心中的氰基多炔和含硫物质：化学和线激发模型
Cyanopolyynes and sulphur bearing species in hot cores: Chemical and line excitation models
摘要：
我们提出的结果，从一个随时间变化的气相化学模型的热核心的物理条件的基础上G305.2+0.2。虽然在热核中观察到了氰基多炔HC_3N，但较长链的HC_5N、HC_7N和HC_9N并不被认为是典型的热核物种。我们目前的结果表明，这些物种可以在热芯条件下形成。我们讨论了在这个过程中的重要化学反应，特别是，表明它们的丰度与从冰粒地幔蒸发的母体物种乙炔有关。氰基多炔显示出作为“化学钟”的希望，这可能有助于未来的观测，以确定热核源的年龄。较大的氰基多炔类丰度在相对较短的时间尺度（~10^2.5年）内增加和减少。我们还讨论了几个含硫物种。我们将非LTE统计平衡激发模型的结果呈现为一系列密度、温度和柱密度相关的等值线图，其中显示了线强度和几个线比。这些有助于解释谱线数据，即使在可用的谱线信息有限的情况下。
英文摘要：
We present results from a time dependent gas phase chemical model of a hot core based on the physical conditions of G305.2+0.2. While the cyanopolyyne HC_3N has been observed in hot cores, the longer chained species, HC_5N, HC_7N, and HC_9N have not been considered typical hot core species. We present results which show that these species can be formed under hot core conditions. We discuss the important chemical reactions in this process and, in particular, show that their abundances are linked to the parent species acetylene which is evaporated from icy grain mantles. The cyanopolyynes show promise as `chemical clocks' which may aid future observations in determining the age of hot core sources. The abundance of the larger cyanopolyynes increase and decrease over relatively short time scales, ~10^2.5 years. We also discuss several sulphur bearing species. We present results from a non-LTE statistical equilibrium excitation model as a series of density, temperature and column density dependent contour plots which show both the line intensities and several line ratios. These aid in the interpretation of spectral line data, even when there is limited line information available.
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