A Programme of Astrophysical Theory and Observations at Leeds

利兹天体物理理论和观测项目

• 批准号: ST/T000287/1
• 负责人: Melvin Hoare
• 金额: $ 293.91万
• 依托单位: University of Leeds
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2020
• 资助国家: 英国
• 起止时间: 2020 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=ST%2FT000287%2F1
• 关键词: Programme; Astrophysical; Theory; Observations; Leeds

This research programme principally addresses how stars and planets form from clouds of dust and gas.Stars form from the clouds of gas that occupy interstellar space and the small dust grains mixed in them. The clouds are highly filamentary and magnetic fields, that also pervade space, are likely to have had a role in shaping them, and controlling their collapse under gravity to form stars. We will conduct computer simulations to ascertain how these molecular clouds are formed and what shapes their complex structure. The formation of stars much more massive than our Sun has proved to be much more problematic as they are rare and distant and produce prodigious amounts of radiation that blow material away rather than let it fall in. As the infalling material gets close in to the star we expect it to complete its journey in a thin disc orbiting the star. Detailed mapping of the molecular emission with the ALMA telescope will reveal whether these discs are stable or whether they will fragment to form binary systems. The inner regions of these discs are hotter and will be studied using the techniques of infrared interferometry and spectroscopy. This reveals spatial information at levels 10 to 100 times better than the Hubble Space Telescope. Such resolution will also reveal if massive proto-stellar binary systems have already formed. At the same time that material is spiralling onto a star via a disc, some of it is being ejected at high speeds along the rotation axis, most likely driven by magnetic fields. To follow these jets further out we will use the highly sensitive network of radio dishes in the UK, e-MERLIN, to map their emission. Most stars form in clusters, but the way in which such systems form and evolve is hotly debated. New information from ESA's Gaia satellite that measures accurate distances and motions of stars will be used alongside other data on the molecular gas clouds to compare with simulations. Novel statistical techniques will be developed to undertake this multi-dimensional comparison. As massive star clusters finally begin to clear away the material from which they were born the combined effect of their radiation, winds and demise as supernovae explosions has a dramatic effect on the surrounding molecular clouds. Computer simulations will be used to tackle this problem to investigate how these feedback processes from star clusters affect the evolution of their giant molecular cloud hosts and the wider galaxy.The discs that surround stars like the Sun as they are forming are the sites where planets form, built up from the coalescence of dust grains. This is only thought to occur in the quieter regions of the disc where turbulence due to the magnetic fields is less strong. How the charged dust particles move relative to the gas is important in the formation process and that will be examined with sophisticated computer simulations. A survey of the properties of these discs around stars slightly more massive than our Sun will be carried out to ascertain why the planetary systems that these stars host appear different to those seen around more solar-like stars. A high resolution study of the chemical make up of planet forming discs will be carried out with the ALMA telescope to find out the initial conditions for planet formation and how far down the road of chemical complexity has already been traveled by this stage. A laboratory study will measure key chemical reaction rates needed to find out how some of the most interesting molecules on the pathway to biological systems are formed. These will be incorporated in to chemical models of the discs to address questions on the origins of life.Near the end of the lives of stars, the very dust grains that begin the planet formation process are themselves produced. We will perform detailed chemical calculations to work out how these silicate minerals are built up from the gaseous elements in the rich, cool, atmospheres of giant stars.

该研究计划主要研究恒星和行星如何从尘埃和气体云中形成。恒星是由占据星际空间的气体云和混合在其中的小尘埃颗粒形成的。云是高度丝状的，磁场也遍布太空，很可能在塑造它们、控制它们在重力作用下塌缩形成恒星方面发挥了作用。我们将进行计算机模拟，以确定这些分子云是如何形成的，以及是什么塑造了它们的复杂结构。事实证明，比太阳质量大得多的恒星的形成问题要大得多，因为它们罕见且遥远，并且会产生大量辐射，将物质吹走而不是让其落入其中。当落入的物质接近恒星时我们预计它会在围绕恒星运行的薄圆盘中完成其旅程。使用 ALMA 望远镜绘制的详细分子发射图将揭示这些圆盘是否稳定，或者它们是否会碎裂形成双星系统。这些圆盘的内部区域温度更高，将使用红外干涉测量和光谱技术进行研究。它揭示的空间信息水平比哈勃太空望远镜好 10 到 100 倍。这样的分辨率还将揭示巨大的原恒星双星系统是否已经形成。与此同时，物质通过圆盘盘旋到恒星上，其中一些物质沿着旋转轴高速喷射，很可能是由磁场驱动的。为了进一步追踪这些喷气机，我们将使用英国高度敏感的无线电天线网络 e-MERLIN 来绘制它们的发射图。大多数恒星形成于星团中，但此类系统形成和演化的方式引起了激烈争论。来自欧空局盖亚卫星的新信息将与分子气体云的其他数据一起用于测量恒星的精确距离和运动，以与模拟进行比较。将开发新的统计技术来进行这种多维比较。当巨大的星团最终开始清除它们诞生的物质时，它们的辐射、风和超新星爆炸消亡的综合效应对周围的分子云产生了巨大的影响。计算机模拟将用于解决这个问题，以研究来自星团的这些反馈过程如何影响其巨型分子云宿主和更广泛的星系的演化。像太阳这样的恒星正在形成时围绕它们的圆盘是行星形成的场所，由尘埃颗粒的聚结而成。据认为，这种情况仅发生在磁盘较安静的区域，那里磁场引起的湍流不太强。带电尘埃颗粒如何相对于气体移动在形成过程中非常重要，这将通过复杂的计算机模拟进行检查。我们将对比太阳质量稍大的恒星周围的这些圆盘的特性进行调查，以确定为什么这些恒星所在的行星系统与类太阳恒星周围的行星系统不同。阿尔玛望远镜将对行星形成盘的化学组成进行高分辨率研究，以找出行星形成的初始条件以及化学复杂性在这一阶段已经走了多远。一项实验室研究将测量关键的化学反应速率，以找出生物系统途径中一些最有趣的分子是如何形成的。这些将被纳入圆盘的化学模型中，以解决有关生命起源的问题。在恒星生命即将结束时，开始行星形成过程的尘埃颗粒本身就会产生。我们将进行详细的化学计算，以弄清楚这些硅酸盐矿物是如何由巨星丰富、凉爽的大气中的气态元素形成的。

项目成果

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). XIII. HCO + and Disk Ionization Structure

行星形成尺度上具有 ALMA 的分子 (MAPS)。

• DOI: http://dx.10.3847/1538-4365/ac143c
• 发表时间: 2021
• 期刊: The Astrophysical Journal Supplement Series
• 作者: Aikawa Y

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) XI: CN and HCN as Tracers of Photochemistry in Disks

行星形成尺度上的 ALMA 分子 (MAPS) XI：CN 和 HCN 作为磁盘中光化学的示踪剂

• DOI: http://dx.10.48550/arxiv.2109.06694
• 发表时间: 2021
• 作者: Bergner J

Dust polarized emission observations of NGC 6334 BISTRO reveals the details of the complex but organized magnetic field structure of the high-mass star-forming hub-filament network

NGC 6334 BISTRO 的尘埃偏振发射观测揭示了高质量恒星形成轮毂-细丝网络复杂但有组织的磁场结构的细节

• DOI: http://dx.10.1051/0004-6361/202038624
• 发表时间: 2021
• 期刊: Astronomy & Astrophysics
• 影响因子: 6.5
• 作者: Arzoumanian D