A Coordinated Laboratory and Astronomical Study of the Seeds of Dust Formation in Giant and Supergiant Stars

巨星和超巨星尘埃形成种子的实验室和天文学协调研究

• 批准号: 1615847
• 负责人: Carl Gottlieb
• 金额: $ 39.99万
• 依托单位: Smithsonian Institution Astrophysical Observatory
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-07-01 至 2021-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1615847&HistoricalAwards=false
• 关键词: Coordinated; Laboratory; Astronomical; Study; Seeds

Astronomers identify molecules in space by matching observed radio signals with measurements made on Earth. By this method, nearly 200 simple molecules (such as water and ammonia) have been identified in our Milky Way galaxy. In this research, scientists will make careful laboratory measurements of new molecules that could be detected by radio telescopes. They will make very precise measurements of the molecules' signature, then go to telescopes to search for these signals in space. The scientists will search for these molecules by observing clouds of gas surrounding stars which blow carbon, oxygen and other elements off their outer layers. Molecules form as the gas from stars cool, and some of these molecules subsequently accumulate and form clumps called 'dust'. These scientists will learn what types of molecules are formed in space around these stars. They are particularly interested in molecules familiar on Earth but which are unknown in space, like silicon oxides (e.g. sand), aluminum oxide (the white film on unpainted aluminum) and titanium oxide (the white color in paint and active component in sunscreen). Some of these oxides of silicon, aluminum, and titanium are thought to be the building blocks of the dust that ultimately forms planets outside our own Solar System.This research begins with laboratory measurements of rotational spectra of new complex molecules containing either two or three silicon, aluminum, or titanium atoms. These molecules are more complex than those previously measured. Next radio astronomers will unravel the chemistry in the inner envelopes of late-type carbon- and oxygen-rich evolved stars, which are a major source of planet forming dust. Owing to many uncertainties in the chemical models of these sources, it is only through an empirical approach, which entails an integrated program of laboratory measurements and astronomical observations at high angular resolution and sensitivity, that astronomers may understand these complex regions. The molecules will be produced in widely used laboratory sources (either glow discharge, discharge nozzle, or laser ablation); their rotational spectra will be measured in the centimeter, millimeter, and sub-millimeter bands either with a Fabry-Perot cavity, broadband chirped pulse spectrometer, or non-resonant absorption cell; and the spectra will be analyzed with standard Hamiltonians and computer programs.The search for the new molecular species in the laboratory will be guided by high level quantum chemical calculations of the structures which will be done by our expert collaborators, and will draw on 30 years of work on reactive molecules of astrophysical interest by our group. In addition to the contribution of this work to astronomy, direct detection of elusive titanium oxides, aluminum oxides, and silicon-bearing molecules in the laboratory will provide detailed information about their structures, which in turn will help applied physicists address vexing questions about the elementary reactions that govern the growth and their wide range of photo-catalytic and photovoltaic applications.This research combines chemistry, electronics, physics and astronomy and is as an excellent topic for teaching, training, and learning. The outreach plan is two-pronged: (1) Provide mentorship and research opportunities to undergraduate and graduate students through programs at the Smithsonian Astrophysical Observatory (SAO) and Harvard; and (2) Create a spectral line molecular radio astronomy module for an innovative learning tool, called 'Spectral Explorer'. The Spectral Explorer is a browser-based spectra visualization and analysis tool. The Spectral Explorer will be used in both high school classroom and public outreach learning settings. The SAO Science Education Department (SED) is developing these events. As part of this effort, the SAO spectroscopy laboratory will be actively engaged in the planning and execution of specific tutorials, videos, spectral datasets, and case study resources which will be centered on the research described in this proposal. The Spectral Explorer lab will be disseminated via partnerships with the NSF, NASA and Smithsonian Affiliations networks to the ten thousand educators currently using SED resources and to the more than 50,000 public/citizen science users.

天文学家通过将观测到的无线电信号与地球上的测量结果相匹配来识别太空中的分子。 通过这种方法，在我们的银河系中已经确定了近200个简单分子（如水和氨）。 在这项研究中，科学家们将对射电望远镜可以探测到的新分子进行仔细的实验室测量。 他们将对分子的特征进行非常精确的测量，然后利用望远镜在太空中寻找这些信号。 科学家们将通过观察恒星周围的气体云来寻找这些分子，这些气体云将碳，氧和其他元素从外层吹走。 当来自恒星的气体冷却时，分子形成，其中一些分子随后积累并形成称为“尘埃”的团块。 这些科学家将了解在这些恒星周围的太空中形成了什么类型的分子。他们对地球上熟悉但在太空中未知的分子特别感兴趣，如氧化硅（例如沙子），氧化铝（未涂漆的铝上的白色薄膜）和氧化钛（油漆中的白色颜色和防晒霜中的活性成分）。 这些硅、铝和钛的氧化物中的一些被认为是最终形成太阳系外行星的尘埃的组成部分。这项研究从实验室测量含有两个或三个硅、铝或钛原子的新复杂分子的旋转光谱开始。 这些分子比以前测量的分子更复杂。 接下来，射电天文学家将揭开晚期富碳富氧演化恒星的内部包层中的化学物质，这些恒星是行星形成尘埃的主要来源。由于这些来源的化学模型中存在许多不确定性，只有通过经验方法，这需要一个高角分辨率和灵敏度的实验室测量和天文观测的综合方案，天文学家才能理解这些复杂的区域。这些分子将在广泛使用的实验室来源中生产（辉光放电、放电喷嘴或激光烧蚀）;它们的旋转光谱将在厘米、毫米和亚毫米波段用法布里-珀罗腔、宽带啁啾脉冲光谱仪或非共振吸收池测量;光谱将用标准的哈密顿量和计算机程序进行分析。在实验室中寻找新的分子物种将以高水平的量子化学计算为指导，这些结构将由我们的专家合作者完成，并将利用我们小组30年来对天体物理学感兴趣的反应分子的工作。除了这项工作对天文学的贡献之外，在实验室中直接检测难以捉摸的钛氧化物、铝氧化物和含硅分子将提供有关其结构的详细信息，这反过来又将帮助应用物理学家解决有关控制生长的基元反应及其广泛的光催化和光伏应用的棘手问题。这项研究结合了化学、电子学、物理学和天文学，并作为一个很好的主题，教学，培训和学习。外联计划双管齐下：（1）通过史密森天体物理观测站和哈佛的方案，为本科生和研究生提供指导和研究机会;（2）为一种称为“光谱探索者”的创新学习工具创建一个光谱线分子射电天文学模块。 Spectral Explorer是一个基于浏览器的光谱可视化和分析工具。 光谱探测器将用于高中课堂和公共推广学习环境。 SAO科学教育部（SED）正在开发这些活动。作为这项工作的一部分，SAO光谱实验室将积极参与规划和执行特定的教程，视频，光谱数据集和案例研究资源，这些资源将以本提案中描述的研究为中心。光谱探测器实验室将通过与NSF、NASA和史密森学会的合作伙伴关系传播给目前使用SED资源的1万名教育工作者和5万多名公众/公民科学用户。