arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1206.2867astro-ph.EP
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在不透明度过渡附近的I型迁移。行星布居综合的广义Lindblad矩公式

On type-I migration near opacity transitions. A generalized Lindblad torque formula for planetary population synthesis

F. S. Masset

摘要:

我们给出了一个表达式的Lindblad扭矩作用于低质量的行星嵌入在一个原行星盘是有效的,即使在位置的表面密度或温度分布不能近似的幂律,如不透明度过渡。在这样的位置,林德布拉德扭矩是已知的遭受强烈偏离其标准值,具有潜在的重要意义的I型迁移,但潮汐相互作用的全面治疗是繁琐的,并不适合行星人口合成模型。我们提出的表达式,保留了简单的标准Lindblad扭矩公式,并给出了准确地再现那些数值模拟的结果,即使在磁盘温度发生突变的位置。我们的研究是通过定制的数值模拟在低质量的制度,在局部等温磁盘,并通过总结在每个Lindblad共振充分分析扭矩估计获得的线性扭矩估计相比。我们修改后的Lindblad扭矩表达式的功能依赖性建议的Lindblad共振,主要有助于扭矩的偏移的估计,在一个磁盘的温度或表面密度的急剧梯度,而新的条款的数值系数进行调整,以寻求与数值协议。作为副作用的结果,我们发现,涡度相关的共转扭矩经历了一个不透明的过渡,可以抵消迁移的推动,我们从数值模拟中发现的证据表明,线性共转扭矩具有不可忽略的依赖于温度梯度,在局部等温磁盘。

英文摘要:

We give an expression for the Lindblad torque acting on a low-mass planet embedded in a protoplanetary disk that is valid even at locations where the surface density or temperature profile cannot be approximated by a power law, such as an opacity transition. At such locations, the Lindblad torque is known to suffer strong deviation from its standard value, with potentially important implications for type I migration, but the full treatment of the tidal interaction is cumbersome and not well suited to models of planetary population synthesis. The expression that we propose retains the simplicity of the standard Lindblad torque formula and gives results that accurately reproduce those of numerical simulations, even at locations where the disk temperature undergoes abrupt changes. Our study is conducted by means of customized numerical simulations in the low-mass regime, in locally isothermal disks, and compared to linear torque estimates obtained by summing fully analytic torque estimates at each Lindblad resonance. The functional dependence of our modified Lindblad torque expression is suggested by an estimate of the shift of the Lindblad resonances that mostly contribute to the torque, in a disk with sharp gradients of temperature or surface density, while the numerical coefficients of the new terms are adjusted to seek agreement with numerics. As side results, we find that the vortensity related corotation torque undergoes a boost at an opacity transition that can counteract migration, and we find evidence from numerical simulations that the linear corotation torque has a non-negligible dependency upon the temperature gradient, in a locally isothermal disk.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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