【摘要】：M型矮星（0.08M⊙M0.8M⊙）是小質(zhì)量的低溫恒星，其數(shù)量眾多，占據(jù)著大部分銀河系的質(zhì)量。由于其質(zhì)量低，所以壽命很長(zhǎng)，且其形成遍布銀河系的各個(gè)演化時(shí)期，可以反映初始形成時(shí)的各種信息，所以人們把M型矮星作為銀河系演化過程的活化石�；谶@一特點(diǎn)，研究M型矮星對(duì)于研究銀河系的結(jié)構(gòu)和運(yùn)動(dòng)學(xué)特性很有意義。 Woolf等人在2012年的文章中提出了‘M型矮星問題’，即簡(jiǎn)單的銀河系化學(xué)演化模型估計(jì)的貧金屬M(fèi)型矮星數(shù)目要比其實(shí)際觀測(cè)到的多。但他們選擇的樣本是金屬豐度低的高銀緯恒星。為了驗(yàn)證太陽系周邊的恒星是否也存在這一問題，本文對(duì)LAMOST先導(dǎo)巡天樣本恒星進(jìn)行了分類，得到了太陽系附近的M型矮星樣本，我們確定了樣本星的金屬豐度，并與銀河系化學(xué)演化的簡(jiǎn)單模型預(yù)言的結(jié)果做了比較。 具體步驟如下： （1）本文利用HAMMER軟件對(duì)LAMOST先導(dǎo)巡天的恒星光譜進(jìn)行分類，挑選出M型矮星。 （2）嘗試多種方法測(cè)量譜線位移，最終確定使用SDSS光譜作為模板匹配譜線，得到譜線位移并確定視向速度。 （3）用HAMMER程序測(cè)得76種原子或分子的譜指數(shù)，，然后利用經(jīng)驗(yàn)公式和CaH2,CaH3,TiO5分子的譜指數(shù)，求出其金屬豐度。再用根據(jù)測(cè)光數(shù)據(jù)，由另一經(jīng)驗(yàn)公式得出絕對(duì)星等，推出其相對(duì)于地球的距離，以及在銀河系的標(biāo)高，并由此得知我們樣本星的位置基本位于銀河系化學(xué)演化模型所提到的距離銀盤垂直距離約+600pc的范圍內(nèi)。 （4）比對(duì)得到的金屬豐度和銀河系簡(jiǎn)單模型，我們發(fā)現(xiàn)太陽系附近確實(shí)存在的M型矮星問題。 （5）此外，在LAMOST的大樣本恒星中，我們還發(fā)現(xiàn)了幾顆較為稀有的富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.
【學(xué)位授予單位】：河北師范大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2013
【分類號(hào)】：P144

【共引文獻(xiàn)】

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相關(guān)博士學(xué)位論文 前4條

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3 胥成林;磁場(chǎng)對(duì)原子能級(jí)占有數(shù)的影響與云南一米太陽塔偏振分析儀設(shè)計(jì)[D];中國(guó)科學(xué)院研究生院（云南天文臺(tái)）;2006年

4 毛銀盾;CCD漂移掃描系統(tǒng)的建立及在同步衛(wèi)星觀測(cè)中的應(yīng)用[D];中國(guó)科學(xué)院研究生院（上海天文臺(tái)）;2007年

本文編號(hào)：2450027