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行星状星云的流体动力学速度场

Hydrodynamical Velocity Fields in Planetary Nebulae

W. Steffen, G. Garcia-Segura, N. Koning

备注：
18 pages, 13 figures, accepted for publication in The Astrophysical Journal,
发表信息：
Astrophys.J.691:696-704,2009
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摘要：

基于轴对称流体动力学模拟和三维重建的形状，我们调查的运动学特征的偏差同源（“哈勃型”）流出的一些典型形状的行星状星云。我们发现，在我们的模拟中考虑的大多数情况下，从哈勃型流的偏差是显着的和可观察的。的偏差是系统的，一个简单的参数化，他们大大提高了形态运动学模型的模拟。我们描述了这样的扩展到一个同源膨胀法，捕获流体动力学轴对称星云在其风吹阶段的全球速度结构。它是极向速度分量的大小，强烈地影响所获得的位置速度图的形状，而不是径向分量的变化。偏差随着星云准直程度的增加而增加，并且在中纬度地区更强。我们描述了潜在的变形，这些偏差可能会产生在3D重建，假设“哈勃型”流出。一般的结论是，详细的形态运动学观测和行星状星云的建模可以揭示星云是否仍处于流体动力学活跃阶段（风阶段），或者它是否已经达到弹道膨胀。

英文摘要：

Based on axi-symmetric hydrodynamical simulations and 3D reconstructions with Shape, we investigate the kinematic signatures of deviations from homologous ("Hubble-type") outflows in some typical shapes of planetary nebulae. We find that, in most situations considered in our simulations, the deviations from a Hubble-type flow are significant and observable. The deviations are systematic and a simple parameterization of them considerably improves morpho-kinematical models of the simulations. We describe such extensions to a homologous expansion law that capture the global velocity structure of hydrodynamical axi-symmetric nebulae during their wind-blown phase. It is the size of the poloidal velocity component that strongly influences the shape of the position velocity diagrams that are obtained, not so much the variation of the radial component. The deviations increase with the degree of collimation of the nebula and they are stronger at intermediate latitudes. We describe potential deformations which these deviations might produce in 3D reconstructions that assume "Hubble-type" outflows. The general conclusion is that detailed morpho-kinematic observations and modeling of planetary nebulae can reveal whether a nebula is still in a hydrodynamically active stage (windy phase) or whether it has reached ballistic expansion.

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