The role of large molecules in space

大分子在太空中的作用

• 批准号: 341270-2011
• 负责人: Cami, Jan
• 金额: $ 2.04万
• 依托单位: University of Western Ontario
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2015
• 资助国家: 加拿大
• 起止时间: 2015-01-01 至 2016-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=572215
• 关键词: role; large; molecules; space

A key role in the physics and chemistry of circumstellar and interstellar environments is played by large carbonaceous molecules such as polycyclic aromatic hydrocarbons (PAHs) and fullerenes. PAHs leave their strong and clear spectral fingerprint in almost all galactic and extragalactic mid-infrared observations. Variations in their observational characteristics depend on the physical conditions of the environment in which they reside, and thus PAHs are potentially powerful tools to study the Universe. However, specifics about the astrophysical PAH population and the underlying causes for these variations remain unclear, limiting their diagnostic power. I developed a method that quantitatively relates physical input parameters (e.g. strength of the radiation field) to spectral features, based on properties of numerous species from the NASA Ames PAH infrared spectroscopic database. I propose to apply this method to the PAH spectra of objects whose environment is well characterized; to investigate the origin of the numerous weak PAH features; and to implement band profile asymmetries in the model in a consistent way. Recently, we detected the largest molecules known to exist in space -- the fullerene species C60 and C70. Just like PAHs, fullerenes turn out to be widespread, and to show subtle variations in their observational characteristics. I propose to carry out several observational projects to study the excitation mechanism of fullerenes, their formation mechanism, evolution, abundance and distribution, and their relation to other extinction features, and in particular the Diffuse Interstellar Bands (DIBs). The proposed program will lead to a better knowledge and understanding of the formation, evolution and distribution of large molecules in space and their specific role in the physics and chemistry of interstellar and circumstellar environments.

多环芳烃(PAHs)和富勒烯等大的碳质分子在星周和星际环境的物理和化学中发挥着关键作用。 在几乎所有的银河系和河外中红外观测中，多环芳烃都留下了强烈而清晰的光谱指纹。它们的观测特征的变化取决于它们所处环境的物理条件，因此多环芳烃可能是研究宇宙的强大工具。然而，关于天体物理多环芳烃种群的具体情况以及导致这些变化的潜在原因仍不清楚，限制了它们的诊断能力。我开发了一种方法，根据NASA Ames PAH红外光谱数据库中众多物种的特性，将物理输入参数(例如辐射场的强度)与光谱特征进行定量关联。我建议将这种方法应用于环境特征良好的对象的PAH谱；调查众多弱PAH特征的来源；并以一致的方式在模型中实现带轮廓不对称。 最近，我们探测到了已知存在于太空中的最大分子--富勒烯物种C60和C70。就像多环芳烃一样，富勒烯被证明是广泛存在的，并且在它们的观测特征上表现出微妙的变化。我计划开展几个观测项目来研究富勒烯的激发机制、它们的形成机制、演化、丰度和分布，以及它们与其他消光特征的关系，特别是弥散星际带(DIB)。 拟议的计划将使人们更好地了解和理解大分子在太空中的形成、演化和分布，以及它们在星际和星际周围环境的物理和化学中的具体作用。