The ionizing effect of low-energy cosmic rays from a class II object on its protoplanetary disc
The ionizing effect of low-energy cosmic rays from a class II object on its protoplanetary disc
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来自 II 类天体的低能宇宙射线对其原行星盘的电离效应
DOI：
10.1093/mnras/stx1889
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发表时间：
2017
影响因子：
4.8
通讯作者：
T. Downes
中科院分区：
文献类型：
--
作者：
D. Rodgers;A. Taylor;T. Ray;T. Downes
研究了来自年轻星星的低能宇宙线对原行星盘的电离效应。我们特别考虑的影响$\sim3\，$GeV的质子注入的内侧边缘的PPD。作为这些CR的结果，电离分数的增加可以允许磁旋转不稳定性在磁盘的其他磁死区中操作。对于假定的典型值，我们发现在$1\，$au处的电离率为$\zeta_\mathrm{CR} \sim 10^{-17}\mathrm{s^{-1}}$。输运方程的求解通过处理的CR扩散的传播。我们发现，增加扩散系数的CR渗透进一步在PPD，而不同的磁盘的质量密度分布被发现有很小的影响。我们调查的CR的能谱的效果。盘风的影响进行检查，包括平流项。对于1 - 100 km\，s^{-1}}$之间的平流风速，对于合理的扩散系数，扩散在此处考虑的所有半径（达到100 km\，s^{-1}}$处占主导地位。总的来说，我们发现，低能量CR可以显着电离PPD的中平面到$\sim\，1\，$au。通过增加CR的亮度或能量，在合理的限度内，它们的径向影响可以在中平面处增加到$\sim2\，$au，但要使中平面进一步电离仍然具有挑战性。
We investigate the ionising effect of low energy cosmic rays (CRs) from a young star on its protoplanetary disk (PPD). We consider specifically the effect of $\sim3\,$GeV protons injected at the inner edge of the PPD. An increase in the ionisation fraction as a result of these CRs could allow the magnetorotational instability to operate in otherwise magnetically dead regions of the disk. For the typical values assumed we find an ionisation rate of $\zeta_\mathrm{CR} \sim 10^{-17}\mathrm{s^{-1}}$ at $1\,$au. The transport equation is solved by treating the propagation of the CRs as diffusive. We find for increasing diffusion coefficients the CRs penetrate further in the PPD, while varying the mass density profile of the disk is found to have little effect. We investigate the effect of an energy spectrum of CRs. The influence of a disk wind is examined by including an advective term. For advective wind speeds between $1-100\mathrm{km\,s^{-1}}$ diffusion dominates at all radii considered here (out to 10$\,$au) for reasonable diffusion coefficients. Overall, we find that low energy CRs can significantly ionise the midplane of PPDs out to $\sim\,1\,$au. By increasing the luminosity or energy of the CRs, within plausible limits, their radial influence could increase to $\sim2\,$au at the midplane but it remains challenging to significantly ionise the midplane further out.
影响因子：
3.2
作者：
V. Mannings;A. Boss;S. Russell
通讯作者：
V. Mannings;A. Boss;S. Russell