Probing the Composition of Planet-Building Material with ALMA

用 ALMA 探索行星建造材料的成分

• 批准号: ST/R000549/1
• 负责人: Catherine Walsh
• 金额: $ 29.54万
• 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: 2018
• 资助国家: 英国
• 起止时间: 2018 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=ST%2FR000549%2F1
• 关键词: Probing; Composition; Planet; Building; Material

Planetary systems, such as our own, are assembled from the material - dust, gas, and ice - contained in the protoplanetary disk around a newly-born star. Studying the dust and gas orbiting nearby young stars gives us unique insight into how our solar system might have looked prior to the inception of the planets. This enables us to answer some fundamental questions on our origins. Is our solar system unique? Do young planetary systems contain information on the physical and chemical conditions in the natal protoplanetary disk? Are planetary atmospheric compositions set by the molecular content of the planet-forming zone in the disk? We are in a unique era to begin to address these questions. Not only is the Kepler space observatory (now K2) revealing the extreme diversity of exoplanetary systems, we now have tools at hand to map the physical structure and chemistry across the planet-forming region of nearby protoplanetary disks. The primary tool we use for this is ALMA, the Atacama Large Millimeter/submillimeter Array. ALMA, an interferometer composed of up to 66 antennas, has the sensitivity and spatial resolution to zoom into the planet-forming zone (< 50 au) and reveal the molecular composition of the birth environment of nascent planets. Recent highlights from ALMA include the first detections of so-called complex organic molecules (COMs), molecules consisting of 6 or more atoms which are also thought to be the main feedstock of larger (prebiotic) molecules. COMs also trace the composition of the ice reservoir hosted on cold (<< 100 K) dust grains which are the building blocks of icy planetesimals such as comets. Also revealed via high spatial resolution observations (~0.1"-0.01") are dust gaps and traps, for which one explanation is sculpting by unseen forming planets. What remains to be determined, is the degree to which dust sculpting can influence the chemistry, thus altering composition of planet-building material (both gas and ice) in situ. This project will investigate the chemistry of organic molecules in nearby planet-forming disks. ALMA observations of gas-phase methanol (CH3OH) of our nearest solar-system analogue, TW Hya, will have the sensitivity and spatial resolution necessary to reveal its distribution and abundance. Of particular interest is whether the methanol emission is coincident with the CO snowline (at 19 au) and/or a planet-carved dust cavity (at 22 au). Analysis of the data using detailed chemical models will reveal its chemical origin and provide vital data for motivating future ALMA searches for even larger (and closer to prebiotic) molecules. In parallel, ALMA observations of known molecular disk tracers, CO, CN, HCN, and HCO+, of the protoplanetary disk encompassing HD 100546, will be used to investigate the effects of planet-carved gaps on the disk chemical structure. HD 100546 is a unique test case because it remains the only known source for which an embedded (proto)planet has been detected in the outer disk (~50 au) and for which existing ALMA data have revealed a dust trap external to the location of the forming planet. The new ALMA data, in combination with detailed chemical models, will reveal whether the forming planet has carved a deep gap in the gas structure at its location, and the molecular emission across the gap will reveal chemical changes induced therein and in the dust traps bordering the planet location. This pilot study, on potential molecular diagnostics of planet-carved gaps, will motivate future ALMA studies of nearby protoplanetary disks which may be host to as yet unseen forming planets.

行星系统（例如我们自己的行星系统）是由材料，灰尘，气体和冰组装而成的 - 围绕新出生的恒星围绕的原月球盘中。研究附近的年轻恒星的灰尘和气体轨道，使我们对行星成立之前的太阳系可能看起来的独特见解。这使我们能够回答有关我们起源的一些基本问题。我们的太阳系独一无二吗？年轻的行星系统是否包含有关出生原理磁盘中物理和化学条件的信息？行星大气组成是由磁盘中行星形成区的分子含量设定的吗？我们正处于一个独特的时代，开始解决这些问题。开普勒空间观测站（现在的K2）不仅揭示了超球星系的极端多样性，而且我们现在拥有手头的工具来绘制附近原理磁盘整个行星形成区域的物理结构和化学。我们为此使用的主要工具是Alma，Atacama大毫米/亚毫米阵列。阿尔玛（Alma）是由多达66个天线组成的干涉仪，具有敏感性和空间分辨率，可以放大到行星形成区域（<50 au），并揭示了新生行星出生环境的分子组成。 ALMA的最新亮点包括对所谓的复合有机分子（COM）的首次检测，由6个或更多原子组成的分子，这些分子也被认为是较大（益生元）分子的主要原料。 COMS还追踪在寒冷（<< 100 K）尘土上托管的冰库的组成，这些冰粒是跨彗星等冰冷的行星的组成部分。还通过高空间分辨率观测值（〜0.1“ -0.01”）是尘埃鸿沟和陷阱，为此，一个解释是通过看不见的形成行星来雕刻的。剩下的要确定的是，灰尘雕刻在多大程度上会影响化学，从而改变了地球建造材料（气体和冰）的原位组成。该项目将调查附近圆盘中有机分子的化学。对我们最近太阳系类似物TW HYA的气相甲醇（CH3OH）的Alma观察将具有揭示其分布和丰度所需的灵敏度和空间分辨率。特别有趣的是，甲醇的发射是否与CO雪线（在19 au）和/或行星雕刻的尘埃腔（22 au）一致。使用详细的化学模型对数据进行分析将揭示其化学起源，并提供重要的数据，以激发未来的ALMA搜索，以探索更大的（较接近益生元）分子。同时，对包含HD 100546的原星盘的已知分子盘示踪剂，CO，CN，HCN和HCO+的ALMA观察将用于研究行星雕刻间隙对盘化学结构的影响。 HD 100546是一个独特的测试用例，因为它仍然是唯一已知的来源，在外部磁盘（〜50 au）中检测到嵌入式（原始）行星，并且现有的ALMA数据揭示了形成行星位置外部的防尘陷阱。新的ALMA数据与详细的化学模型结合使用，将揭示形成行星在其位置的气体结构中是否有一个深层间隙，并且跨间隙的分子发射将揭示其诱导的化学变化以及与行星位置接壤的防尘陷阱。这项针对行星雕刻缝隙的潜在分子诊断的试点研究将激发未来对附近原行星磁盘的ALMA研究，这些磁盘可能寄托于尚未看到的行星。

项目成果

The First Detection of 13C17O in a Protoplanetary Disk: a Robust Tracer of Disk Gas Mass

首次在原行星盘中检测到 13C17O：盘气体质量的稳健示踪剂

• DOI: 10.48550/arxiv.1908.05045
• 发表时间: 2019
• 作者: Booth A

An inherited complex organic molecule reservoir in a warm planet-hosting disk

温暖行星盘中遗传的复杂有机分子库

• DOI: 10.1038/s41550-021-01352-w
• 发表时间: 2021
• 期刊: Nature Astronomy
• 影响因子: 14.1
• 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) XIII：HCO$^$ 和圆盘电离结构

• DOI: 10.48550/arxiv.2109.06419
• 发表时间: 2021
• 作者: Aikawa Y

13C17O suggests gravitational instability in the HL Tau disc

• DOI: 10.1093/mnrasl/slaa014
• 发表时间: 2020-01
• 期刊: Monthly Notices of the Royal Astronomical Society
• 影响因子: 4.8
• 作者: A. Booth;J. Ilee

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) VIII：AS 209 中的 CO 缺口——气体枯竭还是化学加工？

• DOI: 10.48550/arxiv.2109.06263
• 发表时间: 2021
• 作者: Alarcón F