Isotopic and Elemental Abundances in Stars and Planets

恒星和行星中的同位素和元素丰度

• 批准号: 2108686
• 负责人: Ian Crossfield
• 金额: $ 33.43万
• 依托单位: University of Kansas Center for Research Inc
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-09-01 至 2024-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2108686&HistoricalAwards=false
• 关键词: Isotopic; Elemental; Abundances; Stars; Planets

Precise elemental and isotopic abundance measurements provide some of the strongest constraints on the formation and evolution of planets, stars, and galaxies. In the coming decades they will also inform the search for extrasolar biosignatures. This team will determine abundances of Sun-like stars, lower-mass red dwarf stars, substellar objects (brown dwarfs), and exoplanet atmospheres. The team will use this sample to provide insights on planetary evolution, stellar ages, brown dwarf interior modeling, planet and star formation, and models of galactic chemical evolution. They will further develop a craft-based outreach program to build representations of planets using origami, and they will contribute to regional science education by developing a traveling planetarium that will visit communities in rural Kansas. The team uses the iSHELL spectrograph on the 3.5m IRTF telescope to measure elemental abundances of up to 13 elements for each target, including C, O, Mg and Si. In addition, the team has pioneered the use of this instrument to measure abundances of 13CO and C18O (as well as 12C16O), thus providing isotopic abundances of C and O in stellar atmospheres for the first time. These isotopic measurements have been done for two M dwarfs; the objective of this project is to extend these measurements to a variety of other objects that have already been observed, and furthermore to make similar observations for more objects. As a galaxy ages, nucleosynthesis in massive stars and in energetic events will lead to subsequent generations of stars having more of the heavier isotopes of common elements such as C and O than their predecessors. With a galactic chemical evolution model better understood through these measurements, the team will be able to independently infer stellar ages from these isotopic abundances, as well as planetary ages from Mg, Si and other elements that are commonly found on rocky bodies.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

精确的元素和同位素丰度测量值对行星，恒星和星系的形成和演变提供了一些最强的约束。在接下来的几十年中，他们还将告知人们寻求对极性外生物签名。该团队将确定阳光般的恒星，低质量的红色矮人星星，替代物体（Brown Dwarfs）和系外行星氛围。该团队将使用此样本来提供有关行星演化，出色年龄，棕色矮人内部建模，行星和恒星形成以及银河化学演化模型的见解。他们将进一步制定一项基于手工艺的外展计划，以使用折纸来建立行星的代表，并通过开发将访问堪萨斯州农村社区的旅行天文馆来为区域科学教育做出贡献。该团队在350万IRTF望远镜上使用ISHELL光谱仪，用于测量每个目标（包括C，O，MG和SI）最多13个元素的元素丰度。此外，该团队还开创了该仪器的使用来测量13CO和C18O（以及12C16O）的丰富度，因此首次提供C和O的同位素丰度。这些同位素测量已针对两个M矮人进行。该项目的目的是将这些测量值扩展到已经观察到的其他各种对象，然后对更多对象进行类似的观察。作为银河系年龄，大型恒星和能量事件中的核合成将导致随后的恒星比其前任恒星具有更多的共同元素（例如C和O）更重的同位素。通过通过这些测量方法可以更好地理解银河化学演化模型，该团队将能够从这些同位素丰度中独立推断出恒星的年龄，以及来自MG，SI和其他元素的行星年龄，这些元素和其他元素通常在落基身体上发现。这一奖项在NSF的法定任务中反映出了通过评估的构成师的范围，并反映出了构成的构成师的范围，并具有范围的范围。