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arXiv 1608.07040astro-ph.EPmath.DS
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受太阳风、坡印廷-罗伯逊阻力和行星际磁场影响的带电尘埃颗粒动力学

Charged dust grain dynamics subject to solar wind, Poynting-Robertson drag, and the interplanetary magnetic field

Christoph Lhotka, Philippe Bourdin, Yasuhito Narita

摘要:

本文研究了太阳风、坡印廷-罗伯逊阻力和冻结的行星际磁场对太阳系带电尘埃运动的综合影响。为此,我们用平均法导出了长期运动理论,并用非平均运动方程的数值模拟来验证。该理论预言带电粒子的长期运动主要受太阳磁轴的z分量或行星际磁场的法向分量的影响。行星际磁场的法向分量导致半长轴的增大或减小,取决于其函数形式和尘埃粒子的电荷符号。一般认为,在长期时间尺度上,太阳风和光子吸收和再发射(坡印廷-罗伯逊阻力)的共同作用导致了半长轴的减小。相反,我们证明,行星际磁场可能会抵消这些阻力在某些情况下。我们导出了磁场参数与尘埃粒子物理性质以及粒子轨道椭圆的形状和取向之间的简单关系,这是尘埃粒子在半长轴上稳定的必要条件。

英文摘要:

We investigate the combined effect of solar wind, Poynting-Robertson drag, and the frozen-in interplanetary magnetic field on the motion of charged dust grains in our solar system. For this reason we derive a secular theory of motion by the means of averaging method and validate it with numerical simulations of the un-averaged equations of motions. The theory predicts that the secular motion of charged particles is mainly affected by the z-component of the solar magnetic axis, or the normal component of the interplanetary magnetic field. The normal component of the interplanetary magnetic field leads to an increase or decrease of semi-major axis depending on its functional form and sign of charge of the dust grain. It is generally accepted that the combined effects of solar wind and photon absorption and re-emmision (Poynting-Robertson drag) lead to a decrease in semi-major axis on secular time scales. On the contrary, we demonstrate that the interplanetary magnetic field may counteract these drag forces under certain circumstances. We derive a simple relation between the parameters of the magnetic field, the physical properties of the dust grain as well as the shape and orientation of the orbital ellipse of the particle, which is a necessary conditions for the stabilization in semi-major axis.

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