Seeding life on habitable planets

在宜居行星上播种生命

• 批准号: MR/T040726/1
• 负责人: Catherine Walsh
• 金额: $ 145.81万
• 依托单位: University of Leeds
• 依托单位国家: 英国
• 项目类别: Fellowship
• 财政年份: 2021
• 资助国家: 英国
• 起止时间: 2021 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=MR%2FT040726%2F1
• 关键词: Seeding; life; habitable; planets

Two of the great quests of humankind are the hunt for habitable planets and the search for the signatures of life beyond planet Earth. To date, we have discovered more than 4000 planets orbiting other stars, the so-called exoplanets. Of these exoplanets, 21 have a similar size to Earth and also orbit their host star in the habitable zone, a temperate region where liquid water may be able to survive on the planet surface. However, a planet's presence within this temperate zone is only one of several criteria that determines whether or not a planet is truly habitable. So far, we know of only one place in the universe where life has begun and thrived, planet Earth. It is still not well understood why the Earth is seemingly the only planet in the Solar System where life has flourished, especially because our neighbour, Venus, also orbits within the temperate region around the Sun, yet has an atmosphere and surface that is not friendly for life. Rocky planets like the Earth and Venus are formed from cataclysmic collisions of moon-sized bodies, the energy from which would have created a molten, hot surface from which volatiles, such as water, would have boiled away to space.So what happened to make the Earth life friendly? One theory that has stood against scrutiny is that impacts from comets, icy leftovers from the formation of the Solar System, delivered a substantial volume of water and life-friendly (carbon-rich) ingredients to the surface of the young Earth when the crust cooled and solidified. This replenished the planet with the ingredients needed for life to begin. However, this then raises questions on the role of comets in seeding *all* potentially habitable planets with life-friendly ingredients. Are cometary impacts a vital process in the formation of a habitable planet? If so, are comets formed around other stars also carriers of carbon-rich and life-friendly material?This research will scrutinise the criteria needed for habitability by investigating the role of comets in seeding life on *all* potentially habitable planets, using state-of-the-art computational chemical and climate models, in conjunction with state-of-the-art observations of comets and exo-comet forming regions around other stars. My team and I will determine i) whether or not the comet-building material in exoplanet-forming systems are universal carriers of organic-rich material needed to seed life, and ii) whether or not cometary impacts on the atmospheres of rocky exoplanets are an observable phenomenon. The outputs from this research will provide strong constraints on the commonality of habitable planets, and provide a suite of diagnostics to search for evidence of cometary impacts using next generation telescopes that will target potentially habitable exoplanets. This research will revise the definition of "habitability" and will provide atmospheric diagnostics of habitability beyond the already proposed biosignatures.

人类的两大任务是寻找可居住的行星和寻找地球以外的生命特征。迄今为止，我们已经发现了4000多颗围绕其他恒星运行的行星，即所谓的系外行星。在这些系外行星中，有21颗的大小与地球相似，它们也在可居住带围绕着它们的宿主星星运行，这是一个温带地区，液态水可能能够在行星表面生存。然而，一颗行星是否存在于这个温带地区只是决定一颗行星是否真正适合居住的几个标准之一。到目前为止，我们只知道宇宙中有一个地方生命开始并蓬勃发展，那就是地球。目前还不清楚为什么地球似乎是太阳系中唯一一颗生命蓬勃发展的行星，特别是因为我们的邻居金星也在太阳周围的温带地区运行，但其大气层和表面对生命并不友好。像地球和金星这样的岩石行星是由月球大小的天体的灾难性碰撞形成的，碰撞产生的能量会产生一个熔融的、热的表面，挥发物，如水，会沸腾到太空中。那么，是什么让地球对生命友好呢？一个反对审查的理论是，彗星的影响，太阳系形成时的冰冷残留物，在地壳冷却和凝固时，向年轻的地球表面提供了大量的水和生命友好（富含碳）的成分。这为地球补充了生命开始所需的成分。然而，这就提出了彗星在为所有潜在的宜居行星播种生命友好成分方面的作用的问题。彗星撞击是形成可居住行星的重要过程吗？如果是这样的话，围绕其他恒星形成的彗星也是富含碳和生命友好物质的载体吗？这项研究将通过调查彗星在所有潜在可居住行星上播种生命的作用来审查可居住性所需的标准，使用最先进的计算化学和气候模型，结合最先进的彗星和其他恒星周围的外彗星形成区域的观测。我和我的团队将确定i）系外行星形成系统中的彗星构建材料是否是孕育生命所需的富含有机物的物质的普遍载体，ii）彗星对岩石系外行星大气层的影响是否是一种可观察到的现象。这项研究的结果将对可居住行星的共性提供强有力的限制，并提供一套诊断方法，以使用下一代望远镜寻找彗星撞击的证据，这些望远镜将瞄准潜在的可居住系外行星。这项研究将修订“可居住性”的定义，并将提供超出已提出的生物特征的可居住性的大气诊断。

项目成果

Molecules with ALMA at Planet-forming Scales (MAPS). XV. Tracing Protoplanetary Disk Structure within 20 au

• DOI: 10.3847/1538-4365/ac1433
• 发表时间: 2021-09
• 期刊: The Astrophysical Journal Supplement Series
• 作者: A. Bosman;E. Bergin;R. Loomis;S. Andrews;M. V. ’. van ’t Hoff;R. Teague;K. Öberg;V. Guzmán;C. Walsh;Y. Aikawa;Felipe Alarc'on;J. Bae;J. Bergner;A. Booth;G. Cataldi;L. Cleeves;I. Czekala;Jane Huang;J. Ilee;C. Law;R. Le Gal;Yao Liu;F. Long;F. Ménard;H. Nomura;L. Pérez;C. Qi;K. Schwarz;A. Sierra;T. Tsukagoshi;Yoshihide Yamato;D. Wilner;Kecheng Zhang

Molecules with ALMA at Planet-forming Scales (MAPS): A Circumplanetary Disk Candidate in Molecular-line Emission in the AS 209 Disk

• DOI: 10.3847/2041-8213/ac7fa3
• 发表时间: 2022-07
• 期刊: The Astrophysical Journal Letters
• 作者: J. Bae;R. Teague;S. Andrews;M. Benisty;S. Facchini;Maria Galloway-Sprietsma;R. Loomis;Y. Aikawa;Felipe Alarcón;E. Bergin;J. Bergner;A. Booth;G. Cataldi;L. Cleeves;I. Czekala;V. Guzmán;Jane Huang;J. Ilee;N. Kurtovic;C. Law;R. L. Gal;Yao Liu;F. Long;F. Ménard;K. Oberg;L. Pérez;C. Qi;K. Schwarz;A. Sierra;Catherine Walsh;D. Wilner;Kecheng Zhang

Molecules with ALMA at Planet-forming Scales (MAPS). VII. Substellar O/H and C/H and Superstellar C/O in Planet-feeding Gas

• DOI: 10.3847/1538-4365/ac1435
• 发表时间: 2021-09
• 期刊: The Astrophysical Journal Supplement Series
• 作者: A. Bosman;Felipe Alarc'on;E. Bergin;Kecheng Zhang;Merel L. R. van’t Hoff;K. Öberg;V. Guzmán;C. Walsh;Y. Aikawa;S. Andrews;J. Bergner;A. Booth;G. Cataldi;L. Cleeves;I. Czekala;K. Furuya;Jane Huang;J. Ilee;C. Law;R. Le Gal;Yao Liu;F. Long;R. Loomis;F. Ménard;H. Nomura;C. Qi;K. Schwarz;R. Teague;T. Tsukagoshi;Yoshihide Yamato;D. Wilner

Molecules with ALMA at Planet-forming Scales (MAPS). XI. CN and HCN as Tracers of Photochemistry in Disks

• DOI: 10.3847/1538-4365/ac143a
• 发表时间: 2021-09
• 期刊: The Astrophysical Journal Supplement Series
• 作者: J. Bergner;K. Öberg;V. Guzmán;C. Law;R. Loomis;G. Cataldi;A. Bosman;Y. Aikawa;S. Andrews;E. Bergin;A. Booth;L. Cleeves;I. Czekala;Jane Huang;J. Ilee;R. Le Gal;F. Long;H. Nomura;F. Ménard;C. Qi;K. Schwarz;R. Teague;T. Tsukagoshi;C. Walsh;D. Wilner;Yoshihide Yamato

Molecules with ALMA at Planet-forming Scales (MAPS). XVI. Characterizing the Impact of the Molecular Wind on the Evolution of the HD 163296 System

• DOI: 10.3847/1538-4365/ac1ad4
• 发表时间: 2021-09
• 期刊: The Astrophysical Journal Supplement Series
• 作者: A. Booth;B. Tabone;J. Ilee;C. Walsh;Y. Aikawa;S. Andrews;J. Bae;E. Bergin;J. Bergner;A. Bos