本文選題：銀河系 + 銀盤��； 參考：《河北師范大學》2010年碩士論文

【摘要】： 銀盤恒星的金屬豐度和運動學特征是區(qū)分薄盤和厚盤的重要依據(jù),可以為銀河系的結(jié)構(gòu)和化學演化模型提供直接的觀測約束。尤其是研究大樣本恒星的運動學和金屬豐度以及年齡的關系,對于準確解釋銀盤形成和演化的一些問題更具有重要意義。我們基于近年來兩個大樣本恒星的觀測工作,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)、空間運動速度、徑向及法向軌道半徑等參數(shù)。用運動學標準區(qū)分恒星的星族成分,確定了3855顆薄盤星和146顆厚盤星,分別討論了薄盤和厚盤恒星的運動學參數(shù)與金屬豐度、年齡的關系;金屬豐度[Fe/H]與軌道偏心率e、徑向平均軌道半徑Rm以及最大銀盤法向距離Zmax的關系。結(jié)果發(fā)現(xiàn),薄盤恒星和厚盤恒星確實在運動學性質(zhì)上存在較大的差異。具體結(jié)果如下: (1)厚盤恒星和薄盤恒星在空間運動速度上可以區(qū)分開,并且厚盤恒星的空間運動速度彌散明顯大于薄盤恒星。厚盤星的空間運動速度彌散度(σU,σV,σW)=(58±3,34±2,39±2)km/s,薄盤星的(σU,σV,σW)=(31±2,18±1,15±1)km/s。 (2)銀盤恒星的速度彌散度都隨著恒星年齡的增加而逐漸變大,而當年齡約大于10Gyr時速度彌散度突然成倍增加。在薄盤中,σU在恒星年齡約為8Gyr時達到飽和,σU≈41km/s;σV在恒星年齡約為8Gyr時達到飽和,σV≈22km/s;σW在恒星年齡約為6Gyr時達到飽和,σW≈21km/s。而厚盤恒星的空間速度彌散度與恒星年齡沒有關系,并且厚盤恒星和薄盤恒星在W方向速度彌散度上存在間隙,薄盤星σW≤21km/s,厚盤星σW30km/s。 (3)銀盤恒星的軌道偏心率隨金屬豐度的增加而逐漸變小,厚盤恒星的軌道偏心率(e0.25)明顯大于薄盤恒星(e0.20),但當[Fe/H]?0.3以后銀盤恒星的軌道偏心率幾乎保持不變。 (4)沿銀盤徑向,薄盤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(Rm8kpc)豐度梯度接近于0,外盤(Rm≥8kpc)豐度梯度為?0.12dex/kpc。厚盤幾乎不存在徑向金屬豐度梯度。 (5)沿銀盤法向,厚盤和薄盤存在明顯的金屬豐度梯度,大小分別為?0.15 dex/kpc和?0.25dex/kpc,而且薄盤和厚盤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。我們的結(jié)果支持關于銀盤形成和演化的坍縮機制。
[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：2097187