M型矮星的分类和金属丰度
发布时间：2019-03-30 10:11
【摘要】：M型矮星（0.08M⊙M0.8M⊙）是小质量的低温恒星，其数量众多，占据着大部分银河系的质量。由于其质量低，所以寿命很长，且其形成遍布银河系的各个演化时期，可以反映初始形成时的各种信息，所以人们把M型矮星作为银河系演化过程的活化石。基于这一特点，研究M型矮星对于研究银河系的结构和运动学特性很有意义。 Woolf等人在2012年的文章中提出了‘M型矮星问题’，即简单的银河系化学演化模型估计的贫金属M型矮星数目要比其实际观测到的多。但他们选择的样本是金属丰度低的高银纬恒星。为了验证太阳系周边的恒星是否也存在这一问题，本文对LAMOST先导巡天样本恒星进行了分类，得到了太阳系附近的M型矮星样本，我们确定了样本星的金属丰度，并与银河系化学演化的简单模型预言的结果做了比较。 具体步骤如下： （1）本文利用HAMMER软件对LAMOST先导巡天的恒星光谱进行分类，挑选出M型矮星。 （2）尝试多种方法测量谱线位移，最终确定使用SDSS光谱作为模板匹配谱线，得到谱线位移并确定视向速度。 （3）用HAMMER程序测得76种原子或分子的谱指数，，然后利用经验公式和CaH2,CaH3,TiO5分子的谱指数，求出其金属丰度。再用根据测光数据，由另一经验公式得出绝对星等，推出其相对于地球的距离，以及在银河系的标高，并由此得知我们样本星的位置基本位于银河系化学演化模型所提到的距离银盘垂直距离约+600pc的范围内。 （4）比对得到的金属丰度和银河系简单模型，我们发现太阳系附近确实存在的M型矮星问题。 （5）此外，在LAMOST的大样本恒星中，我们还发现了几颗较为稀有的富Li恒星。
[Abstract]:M-type dwarf stars are low-mass low-temperature stars, which occupy the mass of most of the Milky way galaxy. Because of its low quality, long life, and its formation all over the Milky way galaxy at various stages of evolution, can reflect the initial formation of a variety of information, so people take the M-type dwarf star as a living fossil of the evolution process of the Milky way. Based on this feature, the study of M-type dwarf stars is of great significance for the study of the structure and kinematics of the Milky way. In his 2012 paper, Woolf et al proposed the'M-type dwarf problem', that is, the simple chemical evolution model of the Milky way estimates the number of metal-poor M-type dwarfs more than they actually observed. But the sample they chose was a high-silver-latitude star with low metal abundance. In order to verify whether the stars around the solar system also exist or not, this paper classifies the stars from the LAMOST pilot survey, and obtains the samples of M-type dwarfs near the solar system. We have determined the metal abundance of the sample stars. The results are compared with those predicted by a simple model of chemical evolution in the Milky way. The specific steps are as follows: (1) in this paper, the star spectrum of LAMOST pilot survey is classified by HAMMER software, and M-type dwarf stars are selected. (2) try many methods to measure the spectral line displacement, finally determine the use of SDSS spectrum as a template to match the spectral line, get the spectral line displacement and determine the apparent velocity. (3) the spectral indices of 76 kinds of atoms or molecules are measured by HAMMER program, and then the metal abundance of 76 kinds of atoms or molecules is obtained by using the empirical formula and the spectral index of CaH2,CaH3,TiO5 molecules. Based on the photometric data, the absolute magnitude is derived from another empirical formula, and its distance from the Earth, as well as its elevation in the Milky way, is derived. It is found that the position of our sample star is basically within the range of the vertical distance of about 600pc from the silver disk mentioned in the chemical evolution model of the Milky way galaxy. (4) comparing the metal abundance and the simple model of the Milky way, we find that the M-type dwarf star problem does exist in the vicinity of the solar system. (5) in addition, we also found several rare Li-rich stars in the large sample stars of LAMOST.
【学位授予单位】：河北师范大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：P144
本文编号：2450027
[Abstract]:M-type dwarf stars are low-mass low-temperature stars, which occupy the mass of most of the Milky way galaxy. Because of its low quality, long life, and its formation all over the Milky way galaxy at various stages of evolution, can reflect the initial formation of a variety of information, so people take the M-type dwarf star as a living fossil of the evolution process of the Milky way. Based on this feature, the study of M-type dwarf stars is of great significance for the study of the structure and kinematics of the Milky way. In his 2012 paper, Woolf et al proposed the'M-type dwarf problem', that is, the simple chemical evolution model of the Milky way estimates the number of metal-poor M-type dwarfs more than they actually observed. But the sample they chose was a high-silver-latitude star with low metal abundance. In order to verify whether the stars around the solar system also exist or not, this paper classifies the stars from the LAMOST pilot survey, and obtains the samples of M-type dwarfs near the solar system. We have determined the metal abundance of the sample stars. The results are compared with those predicted by a simple model of chemical evolution in the Milky way. The specific steps are as follows: (1) in this paper, the star spectrum of LAMOST pilot survey is classified by HAMMER software, and M-type dwarf stars are selected. (2) try many methods to measure the spectral line displacement, finally determine the use of SDSS spectrum as a template to match the spectral line, get the spectral line displacement and determine the apparent velocity. (3) the spectral indices of 76 kinds of atoms or molecules are measured by HAMMER program, and then the metal abundance of 76 kinds of atoms or molecules is obtained by using the empirical formula and the spectral index of CaH2,CaH3,TiO5 molecules. Based on the photometric data, the absolute magnitude is derived from another empirical formula, and its distance from the Earth, as well as its elevation in the Milky way, is derived. It is found that the position of our sample star is basically within the range of the vertical distance of about 600pc from the silver disk mentioned in the chemical evolution model of the Milky way galaxy. (4) comparing the metal abundance and the simple model of the Milky way, we find that the M-type dwarf star problem does exist in the vicinity of the solar system. (5) in addition, we also found several rare Li-rich stars in the large sample stars of LAMOST.
【学位授予单位】：河北师范大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：P144
【共引文献】
相关期刊论文 前6条
1 毛银盾,唐正宏,李金岭,王叔和;人卫观测中拖长星像的中心定位[J];中国科学院上海天文台年刊;2004年00期
2 李秋莎,张柏荣,陈敬英;天文视频图像采集系统的研究[J];云南天文台台刊;2000年03期
3 吴光节;;日全食观测中的仪器与信息使用[J];天文研究与技术;2009年01期
4 易卫敏;陈东;王传军;;2.4m望远镜曝光时间计算器的设计和实现[J];天文研究与技术;2010年03期
5 程寿国;;基于UBV星等系统的星模拟器控制系统设计[J];科技创新导报;2012年04期
6 邱光良;张雄;钱文枫;;BL Lac天体ON231的CCD测光积分时间与测光误差分析[J];天文研究与技术;2013年01期
相关博士学位论文 前4条
1 唐正宏;图象复原技术在天体测量学中的应用暨河外射电源的精确光学定位[D];中国科学院上海天文台;2001年
2 敦金平;太阳活动区磁场测量和非势特征研究论文[D];中国科学院研究生院（云南天文台）;2002年
3 胥成林;磁场对原子能级占有数的影响与云南一米太阳塔偏振分析仪设计[D];中国科学院研究生院（云南天文台）;2006年
4 毛银盾;CCD漂移扫描系统的建立及在同步卫星观测中的应用[D];中国科学院研究生院（上海天文台）;2007年
本文编号：2450027
本文链接：https://www.wllwen.com/kejilunwen/tianwen/2450027.html
