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arXiv 1304.0993astro-ph.EPphysics.geo-ph
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水行星的内部结构:对它们的发电机源区的影响

Interior Structure of Water Planets: Implications for their dynamo source regions

Bob Yunsheng Tian, Sabine Stanley

摘要:

最近发现的富含水的、亚海王星到海王星质量的短周期轨道系外行星为系外行星发电机的研究提供了一个新的参数空间。我们探索的几何发电机源区域内的参数空间,使用1-D内部结构模型。我们模拟了具有4个化学性质不同的层的行星,这些层包括(1)铁核心,(2)硅酸盐层,(3)H2O层和(4)H/He包层。通过改变行星的总质量在1 - 19个地球质量的范围内,H/He包层的质量分数在0.1 - 5.1%之间,平衡温度在100 - 1000 K之间,对潜在的发电机源区的几何参数空间进行了调查。我们发现,由于水的相图在行星内部的压力和温度条件下的性质,两个不同的发电机源区域的几何形状是可获得的。具体来说,我们发现,较小的行星和行星与较厚的H/He信封很可能是在厚壳发电机的制度。大质量行星和具有薄H/He包层的行星可能处于薄壳发电机的状态。此外,这些参数的微小变化可以产生大的内部结构差异。这意味着有可能根据对行星磁场特征的观测来限制这些参数。

英文摘要:

Recent discoveries of water-rich, sub-Neptunian to Neptunian-massed exoplanets with short-period orbits present a new parameter space for the study of exoplanetary dynamos. We explore the geometry of the dynamo source region within this parameter space using 1-D interior structure models. We model planets with 4 chemically distinct layers that consist of (1) an iron core, (2) a silicate layer, (3) an H2O layer, and (4) an H/He envelope. By varying the total planetary mass in the range of 1 - 19 Earth masses, the mass fraction of the H/He envelope between 0.1 - 5.1%, and the equilibrium temperature between 100 - 1000 K, a survey of the parameter space for potential dynamo source region geometries is conducted. We find that due to the nature of the phase diagram of water at pressure and temperature conditions of planetary interiors, two different dynamo source region geometries are obtainable. Specifically, we find that smaller planets and planets with thicker H/He envelopes are likely to be in the regime of a thick-shelled dynamo. Massive planets and planets with thin H/He envelopes are likely to be in the regime of a thin-shelled dynamo. Also, small variations of these parameters can produce large interior structure differences. This implies the potential to constrain these parameters based on observations of a planet's magnetic field signature.

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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