本文關(guān)鍵詞：引力不穩(wěn)引起角動量傳輸?shù)牟煌Ｐ蛯υ行潜P結(jié)構(gòu)的影響　出處：《吉林大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 原行星盤 塌縮 引力不穩(wěn)定性 粘滯 角動量傳輸 吸積盤

【摘要】：環(huán)繞恒星的盤子的形成是從分子云核塌縮開始的。塌縮持續(xù)過程中，由壓力支撐的恒星在向內(nèi)流動的中心處形成，同時擁有更高角動量的下落物質(zhì)在恒星周圍形成環(huán)繞恒星的盤狀結(jié)構(gòu)。原恒星就是由中央恒星和盤子系統(tǒng)所構(gòu)成的。 大質(zhì)量的盤子很容易產(chǎn)生引力不穩(wěn)定性，引力力矩引起盤子角動量由內(nèi)向外傳遞的效果與粘滯力傳遞角動量機(jī)制很相似，所以LinPringle (1987,1990)提出了“引力不穩(wěn)粘滯”的概念。引力不穩(wěn)粘滯模型在原行星盤的形成與演化模擬中非常適用。但它只是一種方便處理，本質(zhì)上并不是一種粘滯力。 引力不穩(wěn)粘滯在恒星形成中起重要作用，天體物理工作者對于它的研究也不斷深入。他們提出了多種引力不穩(wěn)粘滯模型，這些模型基于不同的原理而有不同的形式。我們的目的就是將不同粘滯形式放在一起進(jìn)行模擬，然后對模擬結(jié)果進(jìn)行比較和分析。這對天體研究有重要的意義。 本論文第一章對研究背景作簡單描述，第二章按時間順序給出不同引力不穩(wěn)粘滯模型的原理、粘滯表達(dá)式、應(yīng)用和產(chǎn)生的結(jié)果等詳細(xì)處理過程，第三章中我們選擇最典型的四種引力不穩(wěn)模型，，代入初始條件相同的同一個恒星形成與演化模型中，對得到的結(jié)果進(jìn)行詳細(xì)分析和比較，來討論不同引力不穩(wěn)模型對原行星盤結(jié)構(gòu)的影響。最后在第四章對我們的工作做總結(jié)和展望。 根據(jù)四種不同引力不穩(wěn)粘滯模型產(chǎn)生的數(shù)據(jù)結(jié)果，我們畫出了對應(yīng)的不穩(wěn)定性參量Q、粘滯系數(shù)和面密度在盤子中的徑向分布，并對它們進(jìn)行分析和對比。我們對比四種模型在盤子形成和演化不同時刻結(jié)構(gòu)的變化，也對比了同一時刻這三種不同參量的相互關(guān)聯(lián)，以及同一時刻同一參量不同模型之間的差別，并給出相應(yīng)的分析和解釋。我們發(fā)現(xiàn)三種不同函數(shù)形式的引力不穩(wěn)粘滯模型（Kratter模型，LinPringle模型和Zhu的指數(shù)模型）對原行星盤結(jié)構(gòu)的影響是一致的，盤子中面密度徑向分布曲線幾乎重合。而引力不穩(wěn)定時（Q1），對整個盤子取常數(shù)引力不穩(wěn)粘滯值為0.02的模型(JinLi模型)，與另外三種模型產(chǎn)生的結(jié)果會有不同。直到盤子演化中晚期，四種模型對應(yīng)盤子面密度分布曲線及粘滯分布曲線才逐漸趨于重合。 因此我們得到結(jié)論，對引力不穩(wěn)粘滯在盤子中進(jìn)行分段（局部）取函數(shù)值，會產(chǎn)生平滑、連續(xù)的面密度和粘滯分布曲線。這些引力不穩(wěn)粘滯模型在盤子形成和演化不同時間和半徑位置產(chǎn)生的面密度分布曲線基本重合，對原行星盤結(jié)構(gòu)的影響比較接近。而引力不穩(wěn)定時對整個盤子取常數(shù)粘滯值的模型，盤子中粘滯分布曲線斷層明顯，沒有一個緩和的連接。因而引起面密度分布曲線不夠平滑。這此結(jié)論在原行星盤形成和演化模擬研究中，對于引力不穩(wěn)定粘滯模型的選取和處理有很大的參考價值。
[Abstract]:The plate forming around the star begins with the collapse of the molecular cloud nucleus. During the process of collapse, the pressurized star forms at the center of the inward flow. At the same time falling matter with higher angular momentum forms a disk structure around the star. The protostar is made up of the central star and the plate system. It is easy to produce gravitational instability in a plate with large mass. The effect of gravitational moment on angular momentum transfer from inside to out is similar to that of viscous force transfer. So LinPringle 1987. In 1990, the concept of "gravitational instability viscosity" was put forward. The gravitational instability viscosity model is very suitable for the formation and evolution of the original planetary disk, but it is only a convenient way to deal with it. Essentially, it is not a viscous force. Gravitational instability viscosity plays an important role in star formation and has been studied deeply by astrophysicists. They have proposed a variety of gravitational instability viscosity models. These models have different forms based on different principles. Our aim is to simulate different viscous forms together. Then the simulation results are compared and analyzed, which is of great significance to the study of celestial bodies. The first chapter of this paper gives a brief description of the research background. The second chapter gives the principle of different gravitational instability viscosity model, viscous expression, application and the results of the detailed processing process according to the time order. In the third chapter, we choose the most typical four kinds of gravitational instability model, and substitute the same star formation and evolution model with the same initial conditions, and analyze and compare the obtained results in detail. The effects of different gravitational instability models on the structure of the original planetary disk are discussed. Finally, our work is summarized and prospected in Chapter 4th. Based on the data obtained from four different gravitational instability models, the radial distributions of the corresponding instability parameters Q, viscosity coefficient and surface density in the plate are drawn. We compare the structural changes of the four models at different times of plate formation and evolution, and also compare the correlation of these three different parameters at the same time. And the differences between different models of the same parameter at the same time, and the corresponding analysis and explanation are given. We find three different forms of gravitational instability viscosity model and Kratter model. The influence of LinPringle model and Zhu's exponential model on the structure of the original planetary disk is consistent. The radial distribution curve of the surface density of the plate almost coincides with that of the plate. The JinLi model with a constant gravitational instability of 0.02 for the whole plate will produce different results from the other three models until the middle and late stage of plate evolution. The four models correspond to the plate surface density distribution curve and the viscous distribution curve. Therefore, we conclude that the piecewise (local) function of the gravitational instability in the plate will produce smoothness. Continuous surface density and viscosity distribution curves. The surface density distribution curves generated by these gravitational instability viscosity models at different time and radius positions of plate formation and evolution are basically coincident with each other. The influence on the structure of the original planetary disk is close, but the viscous curve fault of the plate is obvious when the gravitational instability takes the constant viscosity value for the whole plate. There is no moderate connection, which results in the surface density distribution curve being not smooth enough. This conclusion has been studied in the study of the formation and evolution of the original planetary disk. It has great reference value for the selection and treatment of gravitational instability viscosity model.
【學(xué)位授予單位】：吉林大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：P144

【共引文獻(xiàn)】

相關(guān)博士學(xué)位論文 前1條

1 肖凜;分子云核性質(zhì)對氣態(tài)巨行星最終質(zhì)量的影響[D];吉林大學(xué);2015年

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