Chemical Abundances of Relic Red Giant Stars for Galactic Archeology

像我们银河系这样的星系是如何形成的？元素周期表中所有比氦重的化学元素的来源是什么？我和我的学生将开展银河考古学研究，从根本上探讨这两个重要问题。我们将创建非常古老的红巨星外层可见层(大气)的计算机模型，这些恒星是我们银河系形成的时代的遗迹。这将使我们能够对这些恒星发出的光的光谱进行计算建模，包括光谱的紫外线(UV)、可见光和红外(IR)波段。我们的模型比竞争对手的模型更真实地处理了气体粒子吸收光线并产生恒星发射光谱的方式，并且已经表明，这使我们能够以更高的精度模拟红巨星的光谱。将我们的模拟光谱与国际地面和天基天文台(加拿大是其中许多天文台的合作伙伴)的观测光谱进行比较，将使我们能够确定古老的红巨星的化学成分和其他性质，这些信息对于确定银河系是如何形成和演化至关重要的。我们的建议是及时的，因为许多正在进行或即将开始的大规模观测调查将在未来几年获得数十万颗恒星的光谱，只有用现实的计算模型来解释这些数据，才能实现数据的潜力。在加拿大，我们独一无二地能够提供最先进的模型来解释作为下一代加拿大-法国-夏威夷(NgCFHT)望远镜可行性研究一部分的调查的恒星部分的数据。我们将把一种相关的方法应用于更遥远的恒星群发出的集体光，比如围绕银河系运行的矮小星系，以及在附近更大的星系(如仙女座星系)内发现的大型星团，以确定这些天体的性质和组成。我的研究学生将获得与相关领域相关的关键经验，如地球大气和太阳物理，以及在现代数据中心环境中进行高性能技术计算方法和技能的培训。

How did galaxies such as our own Milky Way Galaxy form? What is the origin of all the chemical elements in the periodic table heavier than Helium? My students and I will carry out research in Galactic archeology to pursue these two important problems in fundamental origins. We will create computer models of the outer visible layers (the atmospheres) of very old red giant stars that are relics from the era in which our Milky Way Galaxy formed. This will allow us to computationally model the spectrum of the light emitted by these stars, including the ultraviolet (UV), visible, and the infrared (IR) bands of the spectrum. Our modelling treats the way that gas particles absorb light and give rise to star’s emitted spectrum more realistically than does rival modelling, and it has been shown that this allows us to simulate red giant stars’ spectra with significantly greater accuracy. Comparison of our simulated spectra to the observed spectra from international ground- and space-based observatories, in many of which Canada is a partner, will allow us to determine the chemical composition and other properties of old red giant stars, and this information is crucial to determining how the Galaxy formed and evolved. Our proposal is timely, because many on-going or soon-to-begin large scale observational surveys of unprecedented scope will obtain spectra of hundreds of thousands of stars over the next few years, and the potential of the data can only be realized if they are interpreted with realistic computational modelling. Within Canada, we are uniquely capable of providing state-of-the-art modelling to interpret data for the stellar component of the surveys being proposed as part of the feasibility study for the Next Generation Canada-France-Hawaii (ngCFHT) telescope. We will apply a related method to the collective light emitted by more remote groups of stars, such as the dwarf galaxies that orbit the Milky Way, and large star clusters that are found within other nearby larger galaxies such the Andromeda galaxy, to determine the properties and composition of those objects, too. My research students will acquire critical experience related to cognate areas such as terrestrial atmospheric and solar physics, and training in methods and skills of high performance technical computing in a modern data centre environment.