标题： 地行星形成：比较不同的初始条件 显示英文标题

标题： Terrestrial-type planet formation: Comparing different types of initial conditions

摘要： 为了研究寡头增长后的类地行星形成，N体模拟中使用的行星胚胎和小行星的初始分布起着重要作用。 这些研究通常基于理论和数值研究的随意初始分布。 我们分析了围绕太阳型恒星的无气态巨行星的行星系统的形成，重点关注结果对小行星和胚胎特定初始分布的敏感性。 类地行星在宜居带（HZ）的形成及其最终含水量是研究重点。 我们从同一原行星盘开发了两组不同的N体模拟。 第一组假设胚胎和小行星的随意初始分布，第二组则从模拟盘气体相演化的半解析模型的结果中获得这些分布。 两组模拟都在宜居带形成了行星。 随意初始条件在宜居带形成的行星质量范围为$0.66M_{\oplus}$到$2.27M_{\oplus}$。 从半解析模型获得的更现实的初始条件形成的行星质量范围为$1.18M_{\oplus}$到$2.21M_{\oplus}$。 两组模拟在宜居带形成的行星含水量质量百分比在 4.5% 到 39.48% 之间。 与含水量最低的行星相比，含水量最高的行星在水源供应方面存在差异。 我们认为宜居带中的行星数量对胚胎和小行星的特定初始分布不敏感，因此两组结果在全球上相似。 然而，主要差异与宜居带行星的吸积历史有关。 这些差异直接影响水富集物质的吸积以及所形成行星的物理特性。 显示英文摘要

摘要： To study the terrestrial-type planet formation during the post oligarchic growth, the initial distributions of planetary embryos and planetesimals used in N-body simulations play an important role. Most of these studies typically use ad hoc initial distributions based on theoretical and numerical studies. We analyze the formation of planetary systems without gas giants around solar-type stars focusing on the sensitivity of the results to the particular initial distributions of planetesimals and embryos. The formation of terrestrial planets in the habitable zone (HZ) and their final water contents are topics of interest. We developed two different sets of N-body simulations from the same protoplanetary disk. The first set assumes ad hoc initial distributions for embryos and planetesimals and the second set obtains these distributions from the results of a semi-analytical model which simulates the evolution of the gaseous phase of the disk. Both sets form planets in the HZ. Ad hoc initial conditions form planets in the HZ with masses from $0.66M_{\oplus}$ to $2.27M_{\oplus}$. More realistic initial conditions obtained from a semi-analytical model, form planets with masses between $1.18M_{\oplus}$ and $2.21M_{\oplus}$. Both sets form planets in the HZ with water contents between 4.5% and 39.48% by mass. Those planets with the highest water contents respect to those with the lowest, present differences regarding the sources of water supply. We suggest that the number of planets in the HZ is not sensitive to the particular initial distribution of embryos and planetesimals and thus, the results are globally similar between both sets. However, the main differences are associated to the accretion history of the planets in the HZ. These discrepancies have a direct impact in the accretion of water-rich material and in the physical characteristics of the resulting planets.