Thermal instability in the presence of the cosmic-ray and ambipolar diffusion
Thermal instability in the presence of the cosmic-ray and ambipolar diffusion
复制标题
宇宙射线和双极扩散存在下的热不稳定性
DOI：
10.1093/mnras/stab3582
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发表时间：
2021
影响因子：
4.8
通讯作者：
AmirAbbas Eslami Shafigh
中科院分区：
文献类型：
--
作者：
M. Gholipour;P. Davoudifar;AmirAbbas Eslami Shafigh
本研究的目的是探讨宇宙射线和双极性扩散对弱电离气体热不稳定性的影响。宇宙射线沿着存在双极扩散的磁场线传播。弱电离气体和宇宙射线被认为是两种不同的相互作用的流体。利用线性摄动分析，考虑热不稳定性的发生，得到两种现象存在时的色散关系。该方程用一些参数描述了稳定和不稳定模式，这些参数取决于宇宙射线和双极扩散。结果表明，微扰传播方向与磁力线之间的夹角对系统的稳定域和不稳定域有重要影响。此外，我们发现有一个与双极扩散率相关的特征波长，可以解释双极扩散是增加了云对坍缩的磁支持，还是减少了云对坍缩的磁支持。最后，研究结果对块状分子云内部结构形成以及星际介质中低质量恒星形成的研究提出了一些新的观点。
The aim of this study is to investigate the impact of the cosmic ray and the ambipolar diffusion on the thermal instability in a weakly ionized gas. The cosmic ray propagates along the magnetic-field line where the ambipolar diffusion is present. The weakly ionized gas and the cosmic ray are considered as two different interacting fluids. Using the linear perturbation analysis, we consider the occurrence of the thermal instability to obtain a dispersion relation in the presence of both phenomena. This equation describes the stable and unstable modes in the terms of some parameters, which depend on the cosmic ray and the ambipolar diffusion. The results show that the angle between the direction of the perturbation propagation and the magnetic-field lines plays an important role on the domains of stability and instability. Furthermore, we found that there is a characteristic wavelength related to the ambipolar diffusivity that explains whether the ambipolar diffusion increases the magnetic support of the cloud against the collapse, or decreases it against the collapse. Finally, the results address some new points in the study of the structure formation within the clumpy molecular clouds as well as the formation of the low-mass stars in the interstellar medium.