Molecular Line Emission Models of Herbig-Haro Objects
Molecular Line Emission Models of Herbig-Haro Objects
复制标题
Herbig-Haro 物体的分子线发射模型
DOI：
10.1086/170777
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发表时间：
1988
期刊：
影响因子：
--
通讯作者：
A. Konigl
中科院分区：
文献类型：
--
作者：
M. Wolfire;A. Konigl
我们提出了星际分子气体团暴露于传播恒星喷流冲击辐射的化学和温度随时间变化的模型。来自冲击的X射线、EUV和FUV辐射引发离子化学反应，并加热团块中的气体。使用有代表性的参数，我们表明，在团块之间的冲击渡越时间上，在团块中产生的电离分子物种的丰度可以超过从稳态模型确定的值几个数量级。由加热气体的碰撞激发可以导致可测量的线发射从几个电离的物种，在以前的调查中的X射线照射的分子气体，我们发现，电子的影响有助于显着这个过程。我们应用这些结果的HCO（+）线发射，已经在几个赫比格-哈罗对象中检测到的解释。我们证明，这张照片提供了一个自然的解释的事实，即线强度通常峰值提前相关的冲击，以及报告的低线中心速度和窄线宽。我们列出了HCO（+）和其他分子种类的几个诊断线强度，可用于推断发射气体中的物理条件。
We present time-dependent models of the chemistry and temperature of interstellar molecular gas clumps that are exposed to the radiation from propagating stellar-jet shocks. The X-ray, EUV, and FUV radiation from the shock initiates ion chemistry and also heats the gas in the clumps. Using representative parameters, we show that, on the shock transit time between the clumps, the abundances of the ionized molecular species that are produced in the clumps can exceed the values determined from steady state models by several orders of magnitude. Collisional excitation by the heated gas can lead to measurable line emission from several ionized species; as in previous investigations of X-ray-irradiated molecular gas, we find that electron impacts contribute significantly to this process. We apply these results to the interpretation of the HCO(+) line emission that has already been detected in several Herbig-Haro objects. We demonstrate that this picture provides a natural explanation of the fact that the line intensity typically peaks ahead of the associated shock, as well as of the reported low line-center velocities and narrow line widths. We tabulate several diagnostic line intensities of HCO(+) and other molecular species that may be used to infer the physical conditions in the emitting gas.