THE NONISOTHERMAL STAGE OF MAGNETIC STAR FORMATION. I. FORMULATION OF THE PROBLEM AND METHOD OF SOLUTION
THE NONISOTHERMAL STAGE OF MAGNETIC STAR FORMATION. I. FORMULATION OF THE PROBLEM AND METHOD OF SOLUTION
复制标题
磁星形成的非等温阶段。
DOI：
10.1088/0004-637x/693/2/1895
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发表时间：
2008
期刊：
影响因子：
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通讯作者：
T. Mouschovias
中科院分区：
文献类型：
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作者：
M. Kunz;T. Mouschovias
我们制定的问题的形成和随后的演变的碎片（或核心）在磁支持，自引力分子云在两个空间维度。六流体（中性粒子、电子、分子和原子离子、带正电、带负电和中性粒子）物理系统由辐射、非理想磁流体动力学方程控制。假设磁通量在任何带电物质中都没有冻结。它的演变是由一个新推导出的广义欧姆定律，占的贡献，弹性和非弹性碰撞双极扩散和欧姆耗散。物种丰度计算使用广泛的化学平衡网络。MRN和均匀粒度分布被认为是。其次，采用灰色通量限制扩散近似的原恒星核心的热演化及其对动力学的影响。现实的温度依赖的晶粒不透明度被用来占各种晶粒组成。我们已经扩大了公开可用的Zeus-MP代码，考虑到所有这些影响，并修改了几个算法，以提高收敛性，准确性和效率。星星形成模拟的结果精确地追踪了原恒星碎片从密度<$103 cm−3到密度<$1015 cm−3的演化，同时严格地解释了非理想MHD过程和辐射传输，在另一篇论文中给出。
We formulate the problem of the formation and subsequent evolution of fragments (or cores) in magnetically supported, self-gravitating molecular clouds in two spatial dimensions. The six-fluid (neutrals, electrons, molecular and atomic ions, positively charged, negatively charged, and neutral grains) physical system is governed by the radiation, nonideal magnetohydrodynamic equations. The magnetic flux is not assumed to be frozen in any of the charged species. Its evolution is determined by a newly derived generalized Ohm's law, which accounts for the contributions of both elastic and inelastic collisions to ambipolar diffusion and Ohmic dissipation. The species abundances are calculated using an extensive chemical-equilibrium network. Both MRN and uniform grain size distributions are considered. The thermal evolution of the protostellar core and its effect on the dynamics are followed by employing the gray flux-limited diffusion approximation. Realistic temperature-dependent grain opacities are used that account for a variety of grain compositions. We have augmented the publicly available Zeus-MP code to take into consideration all these effects and have modified several of its algorithms to improve convergence, accuracy, and efficiency. Results of magnetic star formation simulations that accurately track the evolution of a protostellar fragment from a density ≃103 cm−3 to a density ≃1015 cm−3, while rigorously accounting for both nonideal MHD processes and radiative transfer, are presented in a separate paper.