论文标题
cf $^+$激发星际介质
CF$^+$ excitation in the interstellar medium
论文作者
论文摘要
在星际云中检测CF $^+$的检测可能会使天文学家推断出紫外线释放的分子气中的元素氟丰度和电离分数。由于在星际介质（ISM）几乎无法满足局部热力学平衡（LTE）条件，因此准确确定CF $^+$丰度需要通过辐射和碰撞过程对其非LTE激发进行建模。在这里，我们报告了与para-和ortho-h2碰撞的CF $^+$旋转激发速率系数的量子计算（对于高达150 K的温度）。作为一种应用，我们提出了非LTE激发模型，这些模型揭示了ISM光解离区（PDR）典型的物理条件下种群反转。我们成功地应用了这些模型，以适合先前观察到的CF $^+$发射线，以符合Orion Bar和Horsehead PDR。这些新速率系数实现的辐射转移模型允许使用CF $^+$作为强大的探针研究暴露于强恒星辐射场的分子云。
The detection of CF$^+$ in interstellar clouds potentially allows astronomers to infer the elemental fluorine abundance and the ionization fraction in ultraviolet-illuminated molecular gas. Because local thermodynamic equilibrium (LTE) conditions are hardly fulfilled in the interstellar medium (ISM), the accurate determination of the CF$^+$ abundance requires one to model its non-LTE excitation via both radiative and collisional processes. Here, we report quantum calculations of rate coefficients for the rotational excitation of CF$^+$ in collisions with para- and ortho-H2 (for temperatures up to 150 K). As an application, we present non-LTE excitation models that reveal population inversion in physical conditions typical of ISM photodissociation regions (PDRs). We successfully applied these models to fit the CF$^+$ emission lines previously observed toward the Orion Bar and Horsehead PDRs. The radiative transfer models achieved with these new rate coefficients allow the use of CF$^+$ as a powerful probe to study molecular clouds exposed to strong stellar radiation fields.
