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Theoretical Investigation about a Protoplanetary Disk around a T Tauri Star

关于金牛座 T 星周围原行星盘的理论研究

基本信息

批准号：
04835015
负责人：
MIYAMA Shoken
金额：
$ 1.09万
依托单位：
National Astronomical Observatory
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1992
资助国家：
日本
起止时间：
1992 至 1993
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-04835015/
关键词：
Star Formation Planet Formation Protoplanetary disk Gravitational Instability Transfer of Angular Momentum Numerical Simulation Accretion Disk Brown Dwarf

项目摘要

Because of recent developments in observational instruments, around a T Tauri stars a rotating disk is found and it is considered as a protoplanetary disk. The structure and evolution of such a disk have not been, however, investigated well yet. Hence the purpose of this research project is to construct the model of the protoplanetary disk and to study the stability and evolution of the disk by a linear perturbation theory and numerical simulations.As a beginning in order to study the stability of a disk around the central star, the linear analysis of the perturbation equation has been done. As a result, I find that the stability of the disk is determined by the minimum value (Qmin) of the Toomre's Q in the disk. If the value of Qmin is less that unity, the disk is unstable and its growth rate of the perturbation is nearly equal to the rotational angular velocity. Because of such a high growth-rate, this instability is considered as one of a gravitational instability. On the other hand, if the value of Qmin is greater than unity, such a disk is also unstable. But in this case the instability is considered as one of shear instability from the shape of the eigenfunction.After investigation of the linear stability analysis, I have done numerical simulations to study the nonlinear growth of the perturbations. From numerical computations, the disk with Qmin < 1 fragments into many pieces and they are considered as brown dwarfs because of their mass. From my investigation, the criterion of the stability of the protoplanetary disk is firstly obtained.

由于观测仪器的最新发展，在一颗金牛座T星周围发现了一个旋转的圆盘，它被认为是一个原行星盘。然而，这样一个圆盘的结构和演化还没有得到很好的研究。因此，本研究项目的目的是建立原行星盘的模型，并通过线性摄动理论和数值模拟来研究原行星盘的稳定性和演化。为了研究围绕中心恒星的圆盘的稳定性，本文首先对扰动方程进行了线性分析。因此，我发现磁盘的稳定性是由磁盘中Toomre Q的最小值（Qmin）决定的。当Qmin小于1时，圆盘是不稳定的，其摄动的增长速度几乎等于旋转角速度。由于如此高的增长率，这种不稳定性被认为是引力不稳定性的一种。另一方面，如果Qmin的值大于1，这样的磁盘也是不稳定的。但在这种情况下，从本征函数的形状来看，不稳定性被认为是剪切不稳定性之一。在研究了线性稳定性分析之后，我对扰动的非线性增长进行了数值模拟研究。通过数值计算，Qmin < 1的星盘分裂成许多小块，由于它们的质量大，被认为是褐矮星。通过研究，首次得到了原行星盘稳定性判据。