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.

人类的两项伟大任务是寻找宜居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，并且也在宜居带绕其主恒星运行，宜居带是一个温带地区，液态水可能能够在行星表面生存。然而，行星是否存在于这个温带只是决定行星是否真正适合居住的几个标准之一。到目前为止，我们知道宇宙中只有一个地方生命开始并繁衍生息，那就是地球。目前尚不清楚为什么地球似乎是太阳系中唯一生命繁盛的行星，特别是因为我们的邻居金星也在太阳周围的温带区域内运行，但其大气层和表面并不友好为了生活。像地球和金星这样的岩石行星是由月球大小的天体发生灾难性碰撞而形成的，碰撞产生的能量会产生一个熔化的高温表面，水等挥发物会从该表面沸腾到太空中。对地球生命友好吗？一种经得起推敲的理论是，当地壳冷却时，彗星（太阳系形成时的冰冷残留物）的撞击将大量的水和对生命友好（富含碳）的成分输送到年轻的地球表面。并凝固。这为地球补充了生命开始所需的成分。然而，这引发了人们对彗星在为“所有”潜在宜居行星播撒适合生命的成分方面所扮演的角色的疑问。彗星撞击是宜居行星形成的重要过程吗？如果是这样，围绕其他恒星形成的彗星是否也是富含碳和适合生命的物质的载体？这项研究将通过调查彗星在*所有*潜在宜居行星上播种生命的作用，使用状态-来仔细审查宜居性所需的标准最先进的计算化学和气候模型，结合对彗星和其他恒星周围的外彗星形成区域的最先进的观测。我和我的团队将确定：i）系外行星形成系统中的彗星形成材料是否是孕育生命所需的富含有机物的普遍载体，以及 ii）彗星对岩石系外行星大气的影响是否是一种影响可观察到的现象。这项研究的成果将为宜居行星的共性提供强有力的限制，并提供一套诊断方法，以利用下一代望远镜寻找潜在宜居系外行星的彗星撞击证据。这项研究将修改“宜居性”的定义，并将提供超出已提出的生物特征的宜居性大气诊断。

项目成果

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

行星形成尺度上具有 ALMA 的分子 (MAPS)。

• DOI: http://dx.10.3847/1538-4365/ac143a
• 发表时间: 2021
• 期刊: The Astrophysical Journal Supplement Series
• 作者: Bergner J

Sulphur monoxide emission tracing an embedded planet in the HD 100546 protoplanetary disk

一氧化硫排放追踪 HD 100546 原行星盘中嵌入的行星

• DOI: http://dx.10.1051/0004-6361/202244472
• 发表时间: 2023
• 期刊: Astronomy & Astrophysics
• 影响因子: 6.5
• 作者: Booth A

Molecules with ALMA at Planet-forming Scales (MAPS). VIII. CO Gap in AS 209-Gas Depletion or Chemical Processing?

行星形成尺度上具有 ALMA 的分子 (MAPS)。

• DOI: http://dx.10.3847/1538-4365/ac22ae
• 发表时间: 2021
• 期刊: The Astrophysical Journal Supplement Series
• 作者: Alarcón F

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

行星形成尺度上具有 ALMA 的分子 (MAPS)。

• DOI: 10.3847/1538-4365/ac1435
• 发表时间: 2021-09-13
• 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
• 通讯作者: D. Wilner

UV-driven chemistry as a signpost of late-stage planet formation

紫外线驱动的化学作为晚期行星形成的路标

• DOI: http://dx.10.1038/s41550-022-01831-8
• 发表时间: 2022
• 期刊: Nature Astronomy
• 影响因子: 14.1
• 作者: Calahan J