arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 0910.5299astro-ph.EP
收藏

关于热海王星和超级地球的形成

On the formation of hot Neptunes and super-Earths

D. S. McNeil, R. P. Nelson

备注：
19 pages, 18 figures. Final version accepted to MNRAS 30 September 2009
阅读 PDF
arXiv 页面 ↗HTML 原文 ↗

摘要：

短周期海王星质量天体的发现，现在包括具有三个海王星类似物的显着系统HD 69830（Lovis et al. 2006），对当前的形成模型提出了困难的问题，可能需要对原行星盘进行全球处理。已经提出了几种形成方案，其中大多数将核心吸积的典型寡头图像与I型迁移（例如Terquem & Papaloizou 2007）和行星大气物理学（例如Alibert et al. 2006）相结合。迄今为止，已发表的研究只考虑了少量的祖细胞在后期。这就留下了关于模型的全球可行性的重要问题没有解决。我们试图确定是否最自然的模型-即，采取典型的寡头图片的核心吸积和引入I型迁移-可以成功地形成10个地球质量的物体和更多的磁盘的最里面的部分。这个问题是研究使用两个传统的半分析方法建模寡头增长，以及一个新的并行多区N体代码专门用于处理大动态范围的行星形成问题（麦克尼尔和纳尔逊2009年）。我们发现，这是非常困难的寡头潮汐迁移模型再现所观察到的分布。即使在典型参数的许多变化下，我们也没有形成质量大于8个地球质量的物体。相比之下，形成冰冷的超级地球相对简单。我们的结论是，无论是在短周期海王星系统的原行星盘的初始条件是从我们使用的标准盘模型有很大的不同，或者有重要的物理尚未被理解。

英文摘要：

The discovery of short-period Neptune-mass objects, now including the remarkable system HD69830 (Lovis et al. 2006) with three Neptune analogues, raises difficult questions about current formation models which may require a global treatment of the protoplanetary disc. Several formation scenarios have been proposed, where most combine the canonical oligarchic picture of core accretion with type I migration (e.g. Terquem & Papaloizou 2007) and planetary atmosphere physics (e.g. Alibert et al. 2006). To date, published studies have considered only a small number of progenitors at late times. This leaves unaddressed important questions about the global viability of the models. We seek to determine whether the most natural model -- namely, taking the canonical oligarchic picture of core accretion and introducing type I migration -- can succeed in forming objects of 10 Earth masses and more in the innermost parts of the disc. This problem is investigated using both traditional semianalytic methods for modelling oligarchic growth as well as a new parallel multi-zone N-body code designed specifically for treating planetary formation problems with large dynamic range (McNeil & Nelson 2009). We find that it is extremely difficult for oligarchic tidal migration models to reproduce the observed distribution. Even under many variations of the typical parameters, we form no objects of mass greater than 8 Earth masses. By comparison, it is relatively straightforward to form icy super-Earths. We conclude that either the initial conditions of the protoplanetary discs in short-period Neptune systems were substantially different from the standard disc models we used, or there is important physics yet to be understood.

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。

↑