本文選題：銀河系 + 銀盤(pán)��； 參考：《河北師范大學(xué)》2010年碩士論文

【摘要】： 銀盤(pán)恒星的金屬豐度和運(yùn)動(dòng)學(xué)特征是區(qū)分薄盤(pán)和厚盤(pán)的重要依據(jù),可以為銀河系的結(jié)構(gòu)和化學(xué)演化模型提供直接的觀測(cè)約束。尤其是研究大樣本恒星的運(yùn)動(dòng)學(xué)和金屬豐度以及年齡的關(guān)系,對(duì)于準(zhǔn)確解釋銀盤(pán)形成和演化的一些問(wèn)題更具有重要意義。我們基于近年來(lái)兩個(gè)大樣本恒星的觀測(cè)工作,從其共有的恒星樣本中選取出恒星年齡比較一致(年齡差別在3 Gyr以內(nèi))的4004顆恒星樣本,包括年齡(age17Gyr)、金屬豐度(?1 [Fe/H] 0.5)、空間運(yùn)動(dòng)速度、徑向及法向軌道半徑等參數(shù)。用運(yùn)動(dòng)學(xué)標(biāo)準(zhǔn)區(qū)分恒星的星族成分,確定了3855顆薄盤(pán)星和146顆厚盤(pán)星,分別討論了薄盤(pán)和厚盤(pán)恒星的運(yùn)動(dòng)學(xué)參數(shù)與金屬豐度、年齡的關(guān)系;金屬豐度[Fe/H]與軌道偏心率e、徑向平均軌道半徑Rm以及最大銀盤(pán)法向距離Zmax的關(guān)系。結(jié)果發(fā)現(xiàn),薄盤(pán)恒星和厚盤(pán)恒星確實(shí)在運(yùn)動(dòng)學(xué)性質(zhì)上存在較大的差異。具體結(jié)果如下: (1)厚盤(pán)恒星和薄盤(pán)恒星在空間運(yùn)動(dòng)速度上可以區(qū)分開(kāi),并且厚盤(pán)恒星的空間運(yùn)動(dòng)速度彌散明顯大于薄盤(pán)恒星。厚盤(pán)星的空間運(yùn)動(dòng)速度彌散度(σU,σV,σW)=(58±3,34±2,39±2)km/s,薄盤(pán)星的(σU,σV,σW)=(31±2,18±1,15±1)km/s。 (2)銀盤(pán)恒星的速度彌散度都隨著恒星年齡的增加而逐漸變大,而當(dāng)年齡約大于10Gyr時(shí)速度彌散度突然成倍增加。在薄盤(pán)中,σU在恒星年齡約為8Gyr時(shí)達(dá)到飽和,σU≈41km/s;σV在恒星年齡約為8Gyr時(shí)達(dá)到飽和,σV≈22km/s;σW在恒星年齡約為6Gyr時(shí)達(dá)到飽和,σW≈21km/s。而厚盤(pán)恒星的空間速度彌散度與恒星年齡沒(méi)有關(guān)系,并且厚盤(pán)恒星和薄盤(pán)恒星在W方向速度彌散度上存在間隙,薄盤(pán)星σW≤21km/s,厚盤(pán)星σW30km/s。 (3)銀盤(pán)恒星的軌道偏心率隨金屬豐度的增加而逐漸變小,厚盤(pán)恒星的軌道偏心率(e0.25)明顯大于薄盤(pán)恒星(e0.20),但當(dāng)[Fe/H]?0.3以后銀盤(pán)恒星的軌道偏心率幾乎保持不變。 (4)沿銀盤(pán)徑向,薄盤(pán)總體上存在明顯的金屬豐度梯度,但這一豐度梯度分布由內(nèi)到外是不連續(xù)的,內(nèi)盤(pán)(Rm8kpc)豐度梯度接近于0,外盤(pán)(Rm≥8kpc)豐度梯度為?0.12dex/kpc。厚盤(pán)幾乎不存在徑向金屬豐度梯度。 (5)沿銀盤(pán)法向,厚盤(pán)和薄盤(pán)存在明顯的金屬豐度梯度,大小分別為?0.15 dex/kpc和?0.25dex/kpc,而且薄盤(pán)和厚盤(pán)的法向豐度梯度都表現(xiàn)出隨銀河系演化而逐漸變陡的趨勢(shì)。我們的結(jié)果支持關(guān)于銀盤(pán)形成和演化的坍縮機(jī)制。
[Abstract]:The metallic abundance and kinematic characteristics of silver disk stars are the important basis for distinguishing thin and thick disks, which can provide direct observation constraints for the structural and chemical evolution models of the Milky way galaxy. In particular, the study of the kinematics, the abundance of metals and the age relationship of large sample stars is of great significance for the accurate interpretation of some problems of silver disk formation and evolution. Based on the observations of two large stars in recent years, we have selected 4004 star samples of the same age (age difference within 3 Gyr) from their common star samples. These parameters include age (age17 Gyr), metal abundance (Fer 1 [Fe / H] 0.5), space velocity, radial and normal orbital radius and so on. 3855 thin disk stars and 146 thick disk stars are determined by using kinematics criterion to distinguish star family composition. The relationship between the kinematics parameters of thin disk star and thick disk star and the metal abundance and age are discussed respectively. The relationship between metal abundance [Fe / H] and orbit eccentricity (e), radial mean orbit radius (R _ m) and maximum silver disk normal distance Z _ (max). It is found that there is a great difference in kinematics between thin disk stars and thick disk stars. The results are as follows: (1) thick disk stars and thin disk stars can be distinguished in space motion velocity, and the space motion velocity of thick disk stars is obviously larger than that of thin disk stars. The velocity dispersion of thick disk stars (蟽 U, 蟽 V, 蟽 W) = (58 鹵3) 34 鹵2 39 鹵2 km / s, (蟽 U, 蟽 V, 蟽 W) of thin disk stars = (31 鹵2 18 鹵1 1 鹵15 鹵1) km / s 路s. (2) the velocity dispersion of silver disk stars increases gradually with the increase of star age. In thin disk, 蟽 U reaches saturation at star age about 8 Gyr, 蟽 U 鈮，

本文編號(hào)：2097187