Estimation of ages and masses via carbon and nitrogen abundances for 556 007 giants from LAMOST  

作　　者：Xu Zhang Sven Buder Ya-Qian Wu Gang Zhao 

机构地区：[1]CAS Key Laboratory of Optical Astronomy,National Astronomical Observatories,Chinese Academy of Sciences,Beijing 100101,China [2]School of Astronomy and Space Science,University of Chinese Academy of Sciences,Beijing 100049,China [3]Research School of Astronomy&Astrophysics,Mount Stromlo Observatory,Australian National University,ACT 2611,Australia [4]Center of Excellence for Astrophysics in Three Dimensions(ASTRO-3D),Australia

出　　处：《Research in Astronomy and Astrophysics》2021年第9期29-43,共15页天文和天体物理学研究（英文版）

基　　金：supported by the National Natural Science Foundation of China(Grant Nos.11988101,11890694);National Key R&D Program of China(No.2019YFA0405502);China Scholarship Council。

摘　　要：Estimating ages for a large number of giants is of great importance for studying Galactic evolution.In this work,we determine stellar ages and masses for 556007 giants from LAMOST Data Release 5(DR5)with empirical relations estimated from chemical[C/N]abundance ratios.Our sample reveals the two wellknown sequences in the age-[α/M]relation.The high-αsequence is composed of stars older than 8 Gyr and low-αsequence is composed of stars with age ranging from 0 Gyr to 13.8 Gyr.Our sample also shows a flat age-[M/H]relation up until 12 Gyr.We compare these distributions with Galactic Chemical Evolution models for reference.When looking at the spatial distribution of stars in 2 Gyr age bins,we find that young stars are concentrated towards the Galactic plane and older stars extend to higher height above and below the disk.We find a smooth transition of median Galactic height for different age bins,which suggests a strong age-dependence on Galactic scale height.

关 键 词：stars:fundamental parameters Galaxy:structure Galaxy:evolution Galaxy:abundances 

分 类 号：P152[天文地球—天文学]