Observational Tests of Mixing in Low Mass Stars

低质量恒星混合的观测测试

• 批准号: 9624680
• 负责人: Michael Briley
• 金额: $ 12.66万
• 依托单位: University of Wisconsin-Oshkosh
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1996
• 资助国家: 美国
• 起止时间: 1996-05-01 至 2001-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9624680&HistoricalAwards=false
• 关键词: Observational; Tests; Mixing; Low; Mass

9624680 Briley A program of research in stellar spectroscopy and photometry will be carried out. The research efforts are specifically targeted at providing observational constraints on the chemical abundance modifying mechanisms believed to be operating in evolving low mass stars. The objects to be observed will include galactic globular cluster stars. These stars are known to vary in their light-element abundances. Stars which are in evolving members of old open clusters of stars will also be observed. These types of stars are the among the brightest stars and are most often observed to obtain data for use in chemical abundance determinations. An understanding of the processes which alter the distribution of important elements, such as oxygen and lithium, from their primordial values is required before conclusions can be drawn regarding the chemical history of our galaxy. In collaboration with researchers at other institutions, a series of observational programs will be pursued which will use some of the most recent techniques in astronomical instrumentation. The programs include: 1) A study of isotopic carbon and other light element abundances in cluster stars as probes of deep mixing in the stars and to obtain the sensitivity of the mixing mechanism to stellar mass and composition. 2) The determination of the location of the onset of mixing in moderately metal-poor globular cluster stars. 3) Measurement and analysis of ultaviolet wavelength Nitrogen Hydride (NH) band strengths among bright globular cluster stars to directly determine nitrogen abundances (a crucial input required to assess the role of deep mixing). 4) Placing constraints on the limits of primordial oxygen variations in the globular clusters through the widths of their color-magnitude diagrams. The development of collaborative programs with scientists at other institutions to obtain data, with local reduction and analysis of the data, benefits not only the resident faculty (by stimulating profess ional growth), but also benefits the undergraduate students through early exposure to fundamental research. As a complement to the research projects, a course in basic astrophysics (stellar atmospheres and interiors) is being developed for the Physics/Astronomy Department. A series of animations of complex astrophysical processes will be developed, using current stellar model atmospheres, as a supplement to the course. The resulting animations will be developed in the Mpeg format and made available to other teachers over the Internet. ***

9624680 Briley 将开展恒星光谱学和光度测定研究计划。 这些研究工作的具体目标是提供对化学丰度修改机制的观测限制，这些机制被认为是在演化的低质量恒星中运行的。 待观察的物体将包括银河球状星团恒星。 众所周知，这些恒星的轻元素丰度各不相同。 古老疏散星团中正在演化的恒星也将被观测到。 这些类型的恒星是最亮的恒星之一，最常被观察以获得用于化学丰度测定的数据。 在得出有关银河系化学历史的结论之前，需要了解改变重要元素（例如氧和锂）的原始值分布的过程。 将与其他机构的研究人员合作，开展一系列观测计划，其中将使用一些最新的天文仪器技术。 这些计划包括： 1）研究星团中碳同位素和其他轻元素丰度，作为恒星深度混合的探针，并获得混合机制对恒星质量和成分的敏感性。 2) 确定中度贫金属球状星团恒星中混合开始的位置。 3）测量和分析明亮球状星团恒星中的紫外波长氮氢化物（NH）带强度，以直接确定氮丰度（评估深度混合作用所需的关键输入）。 4）通过颜色-星等图的宽度对球状星团中原始氧变化的极限进行限制。 与其他机构的科学家合作开发项目以获取数据，并对数据进行本地缩减和分析，不仅有利于常驻教师（通过刺激专业发展），也有利于本科生通过早期接触基础研究。 作为研究项目的补充，正在为物理/天文学系开发一门基础天体物理学（恒星大气和内部）课程。 将使用当前的恒星模型大气开发一系列复杂天体物理过程的动画，作为课程的补充。 最终的动画将以 Mpeg 格式开发并通过互联网提供给其他教师。 ***