Gravitational Fragmentation of Expanding Shells. II. Three-dimensional Simulations
Gravitational Fragmentation of Expanding Shells. II. Three-dimensional Simulations
复制标题
膨胀壳的重力破碎。
DOI：
10.1088/0004-637x/733/1/17
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发表时间：
2011
期刊：
影响因子：
--
通讯作者：
K. Iwasaki & S. Inutsuka
中科院分区：
文献类型：
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作者：
K. Iwasaki & S. Inutsuka
我们调查的引力破碎的膨胀壳驱动的H II区域使用三维拉格朗日模拟代码的基础上的黎曼求解器，称为Goddom光滑粒子流体动力学。假设环境气体是均匀的。为了获得高分辨率的几何薄密壳的解析解，我们不是计算整个壳，而是计算一部分壳。我们发现，扰动开始增长早于薄壳近似下的线性分析预测。最不稳定模态的波数比薄壳线性分析的波数大。重力不稳定性的发展伴随着接触不连续面的显著变形。这些结果与Iwasaki等人提出的线性分析是一致的，该分析考虑了厚度方向上的密度分布以及近似激波和接触不连续边界条件。我们推导出有用的解析公式的碎片规模和时代时，引力不稳定性开始增长。
We investigate the gravitational fragmentation of expanding shells driven by H ii regions using the three-dimensional Lagrangian simulation codes based on the Riemann solver, called Godunov smoothed particle hydrodynamics. The ambient gas is assumed to be uniform. In order to attain high resolution to resolve the geometrically thin dense shell, we calculate not the whole but a part of the shell. We find that perturbations begin to grow earlier than predicted by linear analysis under the thin-shell approximation. The wavenumber of the most unstable mode is larger than that in the thin-shell linear analysis. The development of the gravitational instability is accompanied by the significant deformation of the contact discontinuity. These results are consistent with a linear analysis presented by Iwasaki et al. that have taken into account the density profile across the thickness and approximate shock and contact discontinuity boundary conditions. We derive useful analytic formulae for the fragment scale and the epoch when the gravitational instability begins to grow.