A legacy sample of Red Giant stars for Galactic Archaeology: joining asteroseismology, spectroscopy and Gaia data

用于银河考古学的红巨星遗留样本：结合星震学、光谱学和盖亚数据

• 批准号: 428473034
• 负责人: Dr. Marica Valentini
• 金额: --
• 依托单位: Leibniz-Institut für Astrophysik Potsdam (AIP)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2019
• 资助国家: 德国
• 起止时间: 2018-12-31 至 2022-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/428473034?language=en
• 关键词: legacy; sample; Red; Giant; stars

Galactic Archaeology, the discipline that investigates how the Milky Way has formed and evolved, strongly depends on the quality of fundamental stellar properties as distances, masses, ages, and chemical composition. Red giant stars are key targets for Galactic studies, thanks to their large number and intrinsic brightness, that allow to sample different components of our Galaxy, such as the Halo, the Thin and the Thick disc, and the Bulge. They cover a wide range in mass, age, and chemical composition and they are therefore the main targets of ongoing and future large Galactic spectroscopic surveys.Until very recently, however, the usefulness of red giants as tools for Galactic Archaeology was severely limited for two reasons: i) the difficulty in determining a precise stellar surface gravity, log(g), which affects the element abundances determination, since the two are strictly coupled; ii) the large uncertainty on the age, of about ~80%, when it is determined with the classical method of isochrone fitting. The modern, sophisticated models of the chemo-dynamical evolution of the Galaxy need much more stringent observational constraints. How do we reach the precision that is required to better understand the Milky Way and its formation and evolution?With the advent of asteroseismology, the situation has changed significantly: asteroseismology can be used to constrain stellar mass with a precision of 10%, leading to a precision of 30% in age, and it provides log(g) with a precision of 0.01 dex, ten times better than what can be achieved with the classic spectroscopic analysis. We have successfully developed both a method and the tools to combine asteroseismology and spectroscopy: i) a spectroscopic analysis pipeline that uses iteratively the seismic gravity, and ii) a Bayesian tool for mass and age determination that combines asteroseismic quantities with the precise atmospheric parameters from spectroscopy and Gaia data as input.We propose here a project that applies our approach for constructing a sample of red giant stars with precise distances, masses, ages, and element abundances: the red giant legacy sample. We have already secured all the data for the completion of the project: spectra coming from various surveys plus successful observing proposals (GES, APOGEE, RAVE and ESO facilities) and seismic data coming from different space missions (CoRoT, Kepler, K2, TESS). All these data will be analysed in a homogeneous way using our tools. This unprecedented sample will probe different regions of the Galaxy, in particular we will provide a unique insight into the Halo and the Bulge. As final step, the legacy sample will be used as calibration and learning sample for data-driven analysis by future, large spectroscopic survey such as 4MOST.

银河考古学是一门研究银河系如何形成和演化的学科，它在很大程度上依赖于恒星的基本特性，如距离、质量、年龄和化学成分。红巨星是银河系研究的关键目标，这要归功于它们的数量和固有亮度，它们可以对我们银河系的不同组成部分进行采样，比如光晕、薄盘和厚盘以及凸起。它们涵盖了质量、年龄和化学成分的广泛范围，因此它们是正在进行和未来大型银河系光谱调查的主要目标。然而，直到最近，红巨星作为银河考古学工具的用途受到了严重的限制，原因有两个：1)很难确定精确的恒星表面重力，log(g)，这影响了元素丰度的确定，因为两者是严格耦合的；(2)用经典等时拟合方法测定年龄的不确定性大，约为80%。现代的、复杂的银河系化学动力学演化模型需要更严格的观测约束。为了更好地了解银河系及其形成和演化，我们如何才能达到所需的精确度？随着星震学的出现，这种情况发生了显著的变化：星震学可以用10%的精度来约束恒星质量，从而使年龄的精度达到30%，并且它提供的log(g)精度为0.01指数，比经典光谱分析的精度提高了10倍。我们已经成功地开发了一种结合星震学和光谱学的方法和工具：i)一个迭代使用地震重力的光谱分析管道，ii)一个将星震量与光谱和Gaia数据作为输入的精确大气参数相结合的贝叶斯工具，用于质量和年龄测定。我们在这里提出了一个项目，应用我们的方法来构建具有精确距离、质量、年龄和元素丰度的红巨星样本：红巨星遗产样本。我们已经获得了完成项目所需的所有数据：来自各种调查的光谱以及成功的观测建议（GES， APOGEE， RAVE和ESO设施）和来自不同空间任务（CoRoT, Kepler, K2， TESS）的地震数据。所有这些数据将使用我们的工具以同质的方式进行分析。这个前所未有的样本将探测银河系的不同区域，特别是我们将提供对光环和凸起的独特见解。作为最后一步，遗留样本将被用作未来大型光谱调查（如4MOST）的数据驱动分析的校准和学习样本。