利用LAMOST和Gaia数据开展双/多星性质的大样本统计研究

The statistical properties of multiple stars include multiplicity frequency, distribution of mass ratio, distributions of orbital period and eccentricity etc. They are not only the critical quantities in the formation and evolution of multiplicity and in the evolution of star clusters, stellar populations and galaxies, but also play important roles in observational cosmology and blooming multi-messenger astronomy. We propose to identify a few hundred thousands binary/multiple stars with various types from both Gaia astrometric/photometric and LAMOST middle-resolution spectroscopic data using different techniques in this project. These samples will allow for deriving the statistical properties of multiplicities with solar-like primary stars located within 50-200 pc around the Sun. By associating with different environments, different ages and metallicities, we are able to investigate whether these properties are universal in different populations and constrain the forming and evolving processes of multiplicities. We will derive the companion mass functions for different populations and compare them with single stellar mass function so that we can answer a key question in astronomy that whether the initial stellar mass function is universal. The number of the identified binaries/multiple stars in solar neighborhood will be about three orders of magnitude larger than previous works; the complete volume will be also enlarged by a factor of a few. Automatic data processing technique specially for large data samples and Bayesian statistics will be applied to data processing and analysis. The combination of the unique large dataset and advanced statistical analysis methods ensures our leading position among similar studies worldwide. More importantly, we expect that this project can make breakthrough in this field in near future.

双/多星系统的统计特征主要包括双/多星出现频率、质量比分布、轨道周期和偏心率分布等。它们不仅对理解双/多星系统的形成演化至关重要，对星团、星族和星系演化、以致观测宇宙学和多信使天文学也有重大意义。本课题采用多种方法从Gaia天测/测光和LAMOST中分辨率光谱数据中证认数十万各类双/多星，获取太阳附近50-200pc完备体积内主星为类太阳主序星的双/多星系统的大样本统计特征；研究它们在不同环境、年龄和金属丰度中的差异，限制双/多星的形成演化；导出次星质量函数，考察其是否服从单星质量函数，检验质量函数的普适性。同前人工作相比，本课题将太阳近邻双/多星样本提高3个数量级、完备体积扩大数倍，并通过引入大数据处理方法和贝叶斯统计手段获得具有严格统计意义的双/多星性质。独一无二的海量数据和先进统计方法相结合确保本课题在国际同类研究中处于领先水平，力争在双/多星统计特征方向获得重要科学突破。

双/多星系统的统计特征主要包括双/多星出现频率、质量比分布、轨道周期和偏心率分布等。它们不仅对理解双/多星系统的形成演化至关重要，对星团、星族和星系演化、以致观测宇宙学和多信使天文学也有重大意义。本课题采用多种方法从Gaia天测/测光和LAMOST中分辨率光谱数据中证认数十万各类双/多星，获取太阳附近50-200pc完备体积内主星为类太阳主序星的双/多星系统的大样本统计特征；研究它们在不同环境、年龄和金属丰度中的差异，限制双/多星的形成演化；导出次星质量函数，考察其是否服从单星质量函数，检验质量函数的普适性。同前人工作相比，本课题得到太阳近邻双/多星样本提高3个数量级、完备体积扩大数倍，并通过引入大数据处理方法（SLAM）和贝叶斯统计手段获得具有严格统计意义的双/多星性质，并精确测量了恒星参数，完成了LAMOST中分辨率光谱的视向速度校正。并在小质量恒星初始质量函数（IMF）研究获得重大突破，发现天体物理学中一个非常重要的基础理论“恒星初始质量分布规律”会随着恒星金属元素含量和年龄发生显著变化，挑战了恒星初始质量分布规律不变的经典理论，刷新了人类对这一基本概念的认知。独一无二的海量数据和先进统计方法相结合使得本课题研究成果在国际同类研究中处于领先水平，这将对天体物理在双/多星统计特征方向等多个领域的研究产生深远影响。