基于LAMOST DR2的太阳附近G矮星的金属丰度分布函数

发布时间：2018-06-14 21:07

本文选题：郭守敬望远镜 + 金属丰度分布函数　；参考：《上海师范大学》2015年硕士论文

【摘要】：研究银河系矮星的金属丰度分布函数(MDF)对理解银河系化学演化和动力学演化有重要意义。像F、G、K型矮星这样的冷星的年龄,被认为大于或者相当于银盘的年龄。所以,曾经诞生于银河系中的这些恒星都还没有离开主序阶段。通过测量和研究这些冷星的金属丰度分布函数,可以为盘星的形成历史及其演化提供严格的约束。当然,比G矮星更冷的恒星,比如K矮星或者M矮星有比G矮星更长的寿命。然而,鉴于这些恒星光度较小,基于K矮星或M矮星的样本可能仅仅在一个小的区域内,同时,还会有更多的偏差,更难得到一个无偏的、完备的样本。大天区面积多目标光纤光谱望远镜(LAMOST,又称为郭守敬望远镜)可以在一次曝光中同时得到4000个目标天体的低分辨率光谱。郭守敬望远镜具有20平方度的视场,同时具有3.6-4.9m的有效通光半径。此巡天观测有两个观测计划:河外星系巡天(LEGAS)和旨在研究银河系结构的银河系巡天(LEGUE)两部分。我们的研究目标是基于郭守敬望远镜银河系巡天研究太阳附近G矮星的金属丰度分布函数。我们从LAMOST DR2中选出太阳附近的282,217颗G矮星,并研究其金属丰度分布函数。然后,将我们得到的基于LAMOST银河系巡天的G矮星的金属丰度分布函数与源自日内瓦-哥本哈根(GCS)太阳附近的研究(一个星等完备,运动学上无偏的近邻的16,682颗F和G矮星样本)得到的测光较好的irfm样本作比较。我们发现,与GCS样本相比,我们的样本有更高比例的贫金属星。最后,我们认为,当我们基于LAMOST光谱巡天研究太阳附近G矮星的金属丰度分布函数时,可能存在选择效应。
[Abstract]:The study of the metal abundance distribution function (MDF) of the Milky way Dwarfs is of great significance in understanding the chemical and kinetic evolution of the Milky way. Cold stars such as the FGG K dwarf are believed to be older than or equal to the silver disk. So the stars that were born in the Milky way haven't left the main sequence yet. By measuring and studying the metal abundance distribution function of these cold stars, it is possible to provide strict constraints for the formation history and evolution of these cold stars. Of course, stars colder than G dwarfs, such as K dwarfs or M dwarfs, have longer lifetimes than G dwarfs. However, given the small luminosity of these stars, samples based on K or M dwarfs may only be in a small region, and at the same time, there will be more deviations and it will be more difficult to obtain an unbiased, complete sample. LAMOST (also known as Guo Shoujing Telescope) can obtain the low resolution spectra of 4,000 target objects in a single exposure at the same time. The Kuo Shoujing telescope has a field of view of 20 square degrees and an effective radius of 3.6-4.9 m. There are two observational plans for this survey: the Extragalactic Survey (LEGASS) and the Galactic Profiler (LEGUE) to study the structure of the Milky way. Our aim is to study the metal abundance distribution function of G dwarf stars near the Sun based on the Galactic Survey of the Kuo Shoujing Telescope. We select 282217 G dwarfs from LAMOST DR2 and study their metal abundance distribution function. Then, the metal abundance distribution function of the G dwarf star based on the LAMOST Galaxy Survey and the study near the Sun from the Geneva-Copenhagen GCSs (a magnitude complete) are obtained. 16682 samples of F and G dwarfs with unbiased kinematics are compared with irfm samples with better photometry. We found that our sample has a higher proportion of poor metal stars than the GCS sample. Finally, we consider that there may be a selective effect when we study the metal abundance distribution function of G dwarf stars near the sun based on the LAMOST spectral survey.
【学位授予单位】：上海师范大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P148

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