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    Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/7299


    Title: 疏散星團受分子雲影響之數值模擬;Simulations Of Open Cluster Impacted by Molecular Clouds
    Authors: 呂永明;Yeong-Ming Leu
    Contributors: 物理研究所
    Keywords: 動力學;碰撞;分子雲;疏散星團;數值模擬;open cluster;molecular cloud;encounter;simulation
    Date: 2004-06-28
    Issue Date: 2009-09-22 10:54:39 (UTC+8)
    Publisher: 國立中央大學圖書館
    Abstract: 疏散星團的動力學研究可用來探討銀河結構、恆星的形成及演化等相關天文問題。觀測上常因無法準確得知星團的基本物理量(質量、速度、位置等),造成研究上的困擾;理論分析常透過數值模擬的方式模擬相關的天文問題,這樣的方式相較於觀測比較容易掌握基本物理量,方便資料的分析研究。本文擬採用NBODY2數值模擬程式(Aarseth 2001)模擬分子雲對於一接近疏散星團所造成的影響為何。希冀藉由大量的模擬實驗,找出特定規律或趨勢,並透過相關的物理理論,找出此規律背後的物理意義。 疏散星團的結構特質易經由碰撞的過程而破壞,所以透過數值模擬程式的模擬計算,可知分子雲與疏散星團經由重力作用後的情形,透過近千組的模擬實驗,發現分子雲將影響疏散星團的運行軌道與結構。我們發現疏散星團受分子雲作用的時間,一般趨勢是會隨著碰撞參數變大而變大。疏散星團質心運行軌道之散射角也會隨著碰撞參數而有一定的規律。疏散星團受破壞的程度也會隨著不同的分子雲模型而異。分子雲作用疏散星團的時間會隨著碰撞參數變大而變大。 經由近千組的模擬實驗,得知疏散星團質心的散射角會隨碰撞參數增大有先遞增再遞減的規律,且星團看起來已經變形的相當嚴重,但其質心軌跡跟星團是質點(理論值)的情況差別不大。由於疏散星團的結構被破壞了,也直接的影響到其存活時間,透過平均自由程的概念,可約略估計出疏散星團的存活時間。 The dynamics of the open cluster can be used to study galactic structure or the evolution of the star and so on. Generally Speaking, we can’t get the precise mass or velocity or position of the open cluster by astronomy observation. For this reason, researchers often use simulations to study the dynamics of open clusters. In this thesis we adopt the NBODY2 Code(Aarseth 2001)to simulate the encounter between open cluster and molecular cloud. We intend to find some experiential rules to describe the dynamics and define some physical insights behind them. The structure of open cluster can be disrupted by molecular cloud. After about one thousand experiments, we find that the interaction time of the open cluster will increase with impact parameter. We also find that the scattering angle of center mass of the open cluster closely resembles the scattering angle when we treat the open cluster as a point mass. We also use the idea of mean free path to estimate the survival time of the open cluster.
    Appears in Collections:[物理研究所] 博碩士論文

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