Alignment of interstellar grains by mechanical torques: suprathermally rotating Gaussian random spheres
Alignment of interstellar grains by mechanical torques: suprathermally rotating Gaussian random spheres
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DOI：
10.1093/mnras/stw146
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发表时间：
2016-02
影响因子：
4.8
通讯作者：
Indrajit Das;J. Weingartner
中科院分区：
文献类型：
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作者：
Indrajit Das;J. Weingartner
气体颗粒与漂移颗粒的碰撞在颗粒上产生机械扭矩。Lazarian和Hoang最近的工作表明，机械扭矩可能在使螺旋颗粒沿着星际磁场方向排列方面发挥重要作用，即使在亚音速漂移的情况下也是如此。我们计算13个不同的不规则颗粒的机械扭矩，并检查其产生的旋转动力学，假设稳定旋转主轴的最大转动惯量。我们发现，在亚音速漂移制度的对齐效率敏感地依赖于晶粒形状，更有效的对齐形状与大量的机械扭矩，即使在没有漂移的情况下。对于超音速漂移，这种对准通常更有效。需要更严格的动力学分析，以明确地评价机械扭矩在晶粒排列中的作用。
Collisions of gas particles with a drifting grain give rise to a mechanical torque on the grain. Recent work by Lazarian & Hoang showed that mechanical torques might play a significant role in aligning helical grains along the interstellar magnetic field direction, even in the case of subsonic drift. We compute the mechanical torques on 13 different irregular grains and examine their resulting rotational dynamics, assuming steady rotation about the principal axis of greatest moment of inertia. We find that the alignment efficiency in the subsonic drift regime depends sensitively on the grain shape, with more efficient alignment for shapes with a substantial mechanical torque even in the case of no drift. The alignment is typically more efficient for supersonic drift. A more rigorous analysis of the dynamics is required to definitively appraise the role of mechanical torques in grain alignment.