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arXiv 2103.01239astro-ph.EP
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低质量恒星周围超级地球的快速形成

Rapid Formation of Super-Earths Around Low-Mass Stars

Brianna Zawadzki, Daniel Carrera, Eric Ford

摘要:

NASA的TESS任务预计将发现数百颗M矮行星。然而,很少有研究关注行星如何在低质量恒星周围形成。我们的目标是更好地描述M矮行星的形成过程,以填补这一空白,并帮助解释TESS结果。我们使用了十套N体行星形成的模拟不同的气体盘是否存在,胚胎半长轴的初始范围,和初始固体表面密度分布。每一次模拟都从围绕一颗太阳质量为0.2的恒星的147个等质量胚胎开始,并运行1亿年。我们发现行星形成迅速,大多数碰撞发生在前100万年内。相对于无气体环境,气体盘的存在减少了行星的最终数量,并导致行星向内迁移。我们发现,大约四分之一的行星系在气体盘内经历了最后的巨大撞击,这表明一些超级地球可能能够在最后的巨大撞击后重新吸积一个扩展的气体包层,尽管这些可能会受到其他过程的影响,如光蒸发。此外,我们发现,行星的最终分布不保留的初始表面密度分布的斜率的记忆,无论是否存在气体盘。因此,我们的研究结果表明,目前的观测不太可能提供足够的信息来准确地逆向工程的初始分布的固体。

英文摘要:

NASA's TESS mission is expected to discover hundreds of M dwarf planets. However, few studies focus on how planets form around low-mass stars. We aim to better characterize the formation process of M dwarf planets to fill this gap and aid in the interpretation of TESS results. We use ten sets of N-body planet formation simulations which vary in whether a gas disc is present, initial range of embryo semi-major axes, and initial solid surface density profile. Each simulation begins with 147 equal-mass embryos around a 0.2 solar mass star and runs for 100 Myr. We find that planets form rapidly, with most collisions occurring within the first 1 Myr. The presence of a gas disc reduces the final number of planets relative to a gas-free environment and causes planets to migrate inward. We find that roughly a quarter of planetary systems experience their final giant impact inside the gas disc, suggesting that some super-Earths may be able to reaccrete an extended gaseous envelope after their final giant impact, though these may be affected by additional process such as photoevaporation. In addition, we find that the final distribution of planets does not retain a memory of the slope of the initial surface density profile, regardless of whether or not a gas disc is present. Thus, our results suggest that present-day observations are unlikely to provide sufficient information to accurately reverse-engineer the initial distribution of solids.

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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