The Physical and Chemical Properties of Circumstellar Matter

星周物质的物理和化学性质

• 批准号: 9020782
• 负责人: Patrick Huggins
• 金额: $ 6.4万
• 依托单位: New York University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1991
• 资助国家: 美国
• 起止时间: 1991-03-15 至 1994-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9020782&HistoricalAwards=false
• 关键词: Physical; Chemical; Properties; Circumstellar; Matter

An important area of current astronomical research concerns the study of mass loss of red giant stars as they evolve to white dwarfs through the "planetary nebula" stage. Although this research is significant to an understanding of stellar evolution in its own right, it is also important because planetary nebulae are bright and may be observed comparatively easily. Thus, planetary nebulae are particularly convenient objects to study to learn the properties of "circumstellar matter", material which has has been recently ejected from hot stars in densities intermediate between stellar and interstellar gas material. Matter in a similar state also occurs around stars for different reasons, in particular as "disks" around interacting binary stars, B-emission stars, and dense molecular interstellar clouds. However, in these environments it is often difficult to observe this gas and to diagnose its properties. The Principal Investigator (PI) proposes to continue previous NSF-supported research on the physical and chemical properties of matter as it leaves the star in a dense "wind" and eventually mingles with ambient interstellar gas. The PI will determine reaction rates among atoms, molecules, and radiation (starlight) in order to understand the distribution of forms of matter (ions, neutral atoms, and molecules). Because these atoms radiate away thermal energy that they absorb from gas motions, this knowledge will lead to an understanding of the temperature and density of matter at different distances from the star. Comparisons of these theoretical predictions can then be made with new observations from radio (millimeter wavelength) arrays. The correctness of the models will then be evaluated.

当前天文研究的一个重要领域涉及对红色巨星的质量损失，因为它们通过“行星星云”阶段发展为白色矮人。 尽管这项研究对于对恒星演变本身的理解至关重要，但这也很重要，因为行星星云是明亮的，并且可以相对容易地观察到。 因此，行星星云特别方便地研究学习“偶然物质”的特性，最近已经从恒星和星际气体材料之间的密度中弹出的材料。 出于不同的原因，恒星周围也发生了物质，特别是在相互作用的二进制恒星，B发射星和密集的分子星际云的“磁盘”中。 但是，在这些环境中，通常很难观察到这种气体并诊断其性质。 首席研究员（PI）提议继续对物质物理和化学性质的先前支持的研究，因为它使恒星处于密集的“风”状态，并最终与周围的星际气体交织在一起。 PI将确定原子，分子和辐射（星光）之间的反应速率，以了解物质形式的分布（离子，中性原子和分子）。 由于这些原子会从气体运动中吸收的热能辐射，因此这些知识将导致对与恒星不同距离处物质的温度和密度的理解。 然后，可以通过无线电（毫米波长）阵列的新观测来对这些理论预测进行比较。 然后将评估模型的正确性。