Exploring the Nucleosynthesis of Neutron-Capture Elements Through Nebular Spectroscopy

通过星云光谱探索中子捕获元素的核合成

• 批准号: 0901432
• 负责人: Nicholas Sterling
• 金额: $ 8.3万
• 依托单位: Sterling Nicholas C
• 依托单位国家: 美国
• 项目类别: Fellowship Award
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-10-01 至 2012-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0901432&HistoricalAwards=false
• 关键词: Exploring; Nucleosynthesis; Neutron; Capture; Elements

Dr. Nicholas Sterling is awarded an NSF Astronomy and Astrophysics Postdoctoral Fellowship to carry out a program of research and education at Michigan State University. Dr. Sterling will conduct a spectroscopic investigation of planetary nebulae (PNe) and Wolf-Rayet (WR) nebulae, in order to investigate the production of neutron(n)-capture elements (atomic number Z 30) by s-process nucleosynthesis in the progenitor stars of these objects. He will observe PNe with a wide range of progenitor masses in the optical spectral region, which provides access to several n-capture elements that are not detectable in stellar spectra. These data will be used to derive s-process enrichment factors, determine key physical conditions and constrain the element-by-element pattern of s-process enrichments in PN progenitor stars with different initial masses, and reveal the s-process neutron source in intermediate-mass AGB stars. In addition, Dr. Sterling will observe WR nebulae in the infrared in order to detect emission lines of Se and Kr, two of the most highly enriched elements by the weak s-process. This will potentially provide some of the first observational evidence of weak s-process enrichments in massive stars. These observations will be complemented by a laboratory astrophysics study to determine atomic data needed to accurately derive the abundances of the n-capture elements Br and Rb in ionized nebulae. The atomic data will be added to the atomic databases of state-of-the-art photoionization codes and made accessible to the broad astrophysical community. This research has implications for the origin and chemical evolution of trans-iron elements in the Universe, and nucleosynthesis and convective mixing during the late stages of stellar evolution. Moreover, this work will establish an observational and atomic physics foundation upon which future nebular studies can be built, enabling chemical evolution investigations of these elements in Galactic and extragalactic environs.Dr. Sterling will also manage an educational outreach program at Michigan State University comprised of designing and teaching seminars for students, co-teaching Physics and Astronomy Department courses, and advising an undergraduate student research project. The content of the seminars, which will be offered at a range of levels, will draw from the research activities of Dr. Sterling and make them accessible to university students.

Nicholas Sterling博士被授予NSF天文学和天体物理学博士后奖学金，在密歇根州立大学开展研究和教育计划。Sterling博士将对行星状星云（PNe）和Wolf-Rayet（WR）星云进行光谱研究，以研究这些天体的祖星通过s-过程核合成产生中子（n）捕获元素（原子序数Z 30）。他将观察PNe在光学光谱区域中具有广泛的祖质量，这提供了在恒星光谱中无法检测到的几种n-捕获元素。这些数据将被用来推导s-过程的富集因子，确定关键的物理条件和约束的元素，元素的s-过程的富集模式在PN祖星具有不同的初始质量，并揭示在中等质量AGB星的s-过程中子源。此外，Sterling博士还将在红外线上观测WR星云，以探测Se和Kr的发射线，这是弱s过程中最富集的两种元素。这将可能提供一些大质量恒星中弱s过程富集的第一个观测证据。这些观测将得到一项实验室天体物理学研究的补充，以确定准确推导电离星云中n-捕获元素Br和Rb丰度所需的原子数据。原子数据将被添加到最先进的光电离代码的原子数据库中，并提供给广大的天体物理界。这项研究对宇宙中反式铁元素的起源和化学演化，以及恒星演化后期的核合成和对流混合具有重要意义。此外，这项工作将建立一个观测和原子物理学基础，在此基础上可以建立未来的星云研究，使这些元素在银河系和河外环境中的化学演化研究成为可能。斯特林博士还将管理密歇根州立大学的教育推广计划，包括为学生设计和教授研讨会，共同教授物理和天文学系课程，并为一个本科生的研究项目提供建议研讨会的内容，这将是在一系列层次上提供，将借鉴斯特林博士的研究活动，使他们能够接触到大学生。