Pressing Challenges in Post-Main-Sequence Planetary Science

主序后行星科学面临的紧迫挑战

• 批准号: ST/P003850/1
• 负责人: Dimitri Veras
• 金额: $ 58.43万
• 依托单位: University of Warwick
• 依托单位国家: 英国
• 项目类别: Fellowship
• 财政年份: 2017
• 资助国家: 英国
• 起止时间: 2017 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=ST%2FP003850%2F1
• 关键词: Pressing; Challenges; Post; Main; Sequence

MOTIVATIONWhat are rocky planets made of? How are planets born, and how will they die? The composition, formation and fate of planets is of intrinsic human interest, and touches upon some of the most fundamental questions in astrophysics. Our Sun is currently a middle-aged star and will eventually end its life in dramatic fashion. About 6 billion years from now, the Sun will expand and engulf the innermost two planets, Mercury and Venus, and disrupt if not destroy the Earth. During this violent phase, the swollen Sun will vaporise passing asteroids and comets, and leave rocky debris strewn throughout the Solar System amongst the surviving planets. The Sun will then end its life by contracting and cooling as a white dwarf (WD). A WD is small -- the size of the Earth -- but contains half of the mass of the Sun, and 100,000 times the gravity of the Earth.Millions of worlds orbit Sun-like stars that will become WDs. Observations of WDs show a striking feature that links these dying stars with their orbiting rocky remnants: polluted atmospheres. These WD atmospheres are being constantly force-fed a steady stream of rocky debris which reveal the compositions of the building blocks of exo-planets. Detailed observations of the feeding exist, but so far modeling has failed to explain its origin, amount and timescale. These fundamental shortcomings prevent us from painting a a self-consistent picture of planetary evolution.OBJECTIVEI will spearhead the theoretical modeling of old planetary systems, remedying these crucial shortcomings. I will link planetary and stellar formation with their fate. I will model current observations of WDs which host planetary remnants, and make specific predictions to motivate future observations. MY BACKGROUNDI see myself on a well-traced trajectory to consolidate my leadership role in the modelling/theoretical aspects of dying planetary systems, where there is a dearth of and need for research initiatives. As a PhD student, before the later discovery of exoplanets beyond 5 au, I demonstrated how planets formed in inner regions could migrate outwards through either disc-planet interactions or gravitational scattering. As a postdoctoral associate, I demonstrated how direct imaging campaigns can observe populations of these planets. This background instilled in me a desire to be at the forefront of pioneering new research, and motivated and empowered me to extend my interests to a new, growing area of astrophysics: the end state of planetary systems. METHODOLOGYModeling old planetary systems is challenging both numerically and analytically because both the planet and star undergo significant orbital and physical changes. I have already developed numerical codes that incorporate both types of variations self-consistently, and derived analytical formulae to model these changes. I will employ and expand upon this foundation to accomplish the tasks in this proposal.WHY THIS RESEARCH IS IMPORTANTAnalysis of polluted WD atmospheres represent the *only* substantial way to probe the bulk chemical composition of exo-planets. Understanding the fate of planetary systems is the missing piece in our knowledge of the full life cycle of these systems.IMPACTThe project results will transform our understanding about the life cycle of planetary systems, answering fundamental questions about the future of our world and other worlds. The proposed theoretical work is necessary to fully exploit the scientific investment into experimental facilities. By considering the end state rather than the formation of planetary systems, the project will bring a fresh perspective scientifically and for the lay person. Also, the topic of planetary death garners significant public interest, as demonstrated by media attention that the topic has received (http://www.bbc.co.uk/news/science-environment-24491845), providing pathways for outreach activities.

岩石行星是由什么构成的？行星是如何诞生的，又将如何消亡？行星的组成、形成和命运是人类固有的兴趣所在，并触及天体物理学中一些最基本的问题。我们的太阳目前是一颗中年星星，最终将以戏剧性的方式结束它的生命。大约60亿年后，太阳将膨胀并吞没最里面的两颗行星，水星和金星，如果不是摧毁地球，也会破坏地球。在这个剧烈的阶段，膨胀的太阳将蒸发经过的小行星和彗星，并在整个太阳系幸存的行星中留下岩石碎片。然后太阳将结束其生命的收缩和冷却作为一个白色矮星（WD）。WD很小--和地球一样大--但包含太阳质量的一半，地球引力的100，000倍。数百万个世界围绕着类似太阳的恒星运行，这些恒星将成为WD。对WD的观测显示了一个惊人的特征，将这些垂死的恒星与它们的轨道岩石残余物联系起来：污染的大气层。这些WD大气层不断地被强迫馈送一股稳定的岩石碎片流，这些碎片揭示了系外行星的组成成分。对进食的详细观察是存在的，但到目前为止，模型未能解释其起源，数量和时间尺度。这些根本性的缺陷使我们无法描绘出一幅自洽的行星演化图景，而KARTIVEI将率先对古老的行星系统进行理论建模，弥补这些关键性的缺陷。我将把行星和恒星的形成与它们的命运联系起来。我将模拟目前的观察WD的主机行星遗迹，并作出具体的预测，以激励未来的观测。我的团队看到自己在一个良好的跟踪轨迹，以巩固我在垂死行星系统的建模/理论方面的领导作用，那里缺乏和需要研究计划。作为一名博士生，在后来发现5 Au以上的系外行星之前，我演示了在内部区域形成的行星如何通过盘-行星相互作用或引力散射向外迁移。作为一名博士后助理，我展示了直接成像活动如何观察这些行星的人口。这种背景使我渴望站在开拓新研究的最前沿，并激励和授权我将我的兴趣扩展到天体物理学的一个新的、不断发展的领域：行星系统的最终状态。 方法论对古老的行星系统进行建模在数值和分析上都具有挑战性，因为行星和星星都经历了显著的轨道和物理变化。我已经开发了数值代码，将这两种类型的变化自洽，并推导出分析公式来模拟这些变化。我将在这个基础上运用和扩展，以完成这项建议中的任务。为什么这项研究是重要的？分析被污染的WD大气是探测系外行星大量化学成分的唯一重要途径。了解行星系统的命运是我们对这些系统的整个生命周期的知识中缺失的部分。影响项目结果将改变我们对行星系统生命周期的理解，回答有关我们世界和其他世界未来的基本问题。建议的理论工作是必要的，以充分利用科学投资到实验设施。通过考虑最终状态而不是行星系统的形成，该项目将为科学和外行带来新的视角。此外，正如媒体对该专题的关注所表明的那样，行星死亡专题引起了公众的极大兴趣（http：//www.bbc.co.uk/news/science-environment-24491845），为外联活动提供了途径。

项目成果

Driving white dwarf metal pollution through unstable eccentric periodic orbits

• DOI: 10.1051/0004-6361/201935996
• 发表时间: 2019-08
• 期刊: Astronomy & Astrophysics
• 影响因子: 6.5
• 作者: K. Antoniadou;D. Veras

A remnant planetary core in the hot-Neptune desert

炎热的海王星沙漠中的残余行星核心

• DOI: 10.48550/arxiv.2003.10314
• 发表时间: 2020
• 作者: Armstrong D

DebrisWatch I: A survey of faint geosynchronous debris

• DOI: 10.1016/j.asr.2020.08.008
• 发表时间: 2020-08
• 期刊: Advances in Space Research
• 影响因子: 2.6
• 作者: J. Blake;P. Chote;D. Pollacco;W. Feline;G. Privett;A. Ash;S. Eves;Arthur Greenwood;N. Harwood;T. Marsh;D. Veras;C. Watson

A Gap in the Mass Distribution for Warm Neptune and Terrestrial Planets

• DOI: 10.3847/2041-8213/ab2ba2
• 发表时间: 2019-06
• 期刊: The Astrophysical Journal Letters
• 作者: David J Armstrong;F. Meru;D. Bayliss;G. Kennedy;D. Veras