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首页> 外文期刊>PASJ: Publications of the Astronomical Society of Japan >Observational identification of first cores: Non-LTE radiative transfer simulation
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Observational identification of first cores: Non-LTE radiative transfer simulation

机译：第一核的观察识别：非LTE辐射转移模拟

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摘要

A first core is a first hydrostatic object formed in the course of dynamical contraction of a molecular cloud core. Since the inflow pattern changes drastically both before and after first core formation, it is regarded as a milestone in the star-formation process. In order to identify the first core from a mapping observation, the features expected for the first core are studied for CS rotation transitions at radio wavelengths. The non-LTE (local thermodynamical equilibrium) radiation transfer is calculated for the results of radiation magnetohydrodynamical simulations of the contraction of the magnetized molecular cloud core in rotation (Tomida et al. 2010b, ApJ, 714, L58). We used the Monte-Carlo method to solve the non-LTE radiation transfer in a nested grid hierarchy. In the first core phase, an outflowarises from the vicinity of the first core due to a twisted magnetic field amplified by rotation of the contracting gas disk. The disk and outflow system has several characteristic observational features: (i) relatively opaque lines indicate asymmetry in the emission lines in which the blue side is stronger than the red side (an infall signature of the envelope); (ii) in the edge-on view, the disk has a signature of simultaneous rotation and infall, i.e., the integrated intensity of the approaching side is brighter than that of the receding side and the gradient in the intensity-weighted velocity is larger in the approaching side; (iii) the observed outflow indicates rotation around the rotation axis. The size of the outflow gives the approximate age after the first core is formed, since the outflow is not expected for the earlier runaway isothermal collapse phase.
机译：第一核是在分子云芯的动态收缩过程中形成的第一静液压物体。由于流入模式在第一核心形成之前和之后都发生了急剧变化，因此它被认为是星形形成过程中的里程碑。为了从映射观察识别第一核心，研究了在无线电波长下的CS旋转转换所期望的预期的特征。计算非LTE（局部热力学平衡）辐射转移，用于旋转磁化分子云核心收缩的辐射磁流动模拟的结果（Tomida等，2010B，APJ，714，L58）。我们使用Monte-Carlo方法来解决嵌套网格层次结构中的非LTE辐射传输。在第一核心阶段中，由于通过收缩气体盘的旋转而放大的扭曲磁场，从第一芯附近的出现。磁盘和流出系统具有多个特征观测特征：（i）相对不透明的线表示排放线中的不对称性，其中蓝色侧比红色侧更强（信封的空头签名）; （ii）在视图中，磁盘具有同时旋转和件的签名，即接近侧的集成强度比后退侧更亮，并且强度加权速度的梯度更大接近的一侧; （iii）观察到的流出表示围绕旋转轴的旋转。由于早期失控等温塌陷阶段，外流在形成第一核之后，流出的大小给出了近似年龄。

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