A SEMI-ANALYTICAL DESCRIPTION FOR THE FORMATION AND GRAVITATIONAL EVOLUTION OF PROTOPLANETARY DISKS
A SEMI-ANALYTICAL DESCRIPTION FOR THE FORMATION AND GRAVITATIONAL EVOLUTION OF PROTOPLANETARY DISKS
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DOI：
10.1088/0004-637x/770/1/71
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发表时间：
2013-05
期刊：
影响因子：
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通讯作者：
Sanemichi Z. Takahashi;S. Inutsuka;M. Machida
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作者：
Sanemichi Z. Takahashi;S. Inutsuka;M. Machida
研究了非磁化分子云中自引力原行星盘的形成过程。在大质量盘形成的早期，由于引力矩的作用，角动量被重新分配。我们开发了一个简化的一维吸积盘模型，考虑到气体从信封上的磁盘和转移的角动量在磁盘上的有效粘度。首先，我们估计气体吸积率从云核到磁盘的气体压力和重力作用在云核上的近似估计的影响。我们制定的有效粘度作为一个函数的Toomre Q参数，衡量当地的引力稳定性的旋转薄盘。我们使用一个函数的粘度，当磁盘的引力不稳定的变化与Q敏感。我们发现在盘的演化过程中存在一种很强的自我调节机制。在原行星盘的形成阶段，表面密度的演化不依赖于有效粘性模型的其他细节，如粘性系数的前因子。接下来，为了验证我们的模型，我们比较了我们的配方与三维流体动力学模拟计算的磁盘的时间演化。一维吸积盘模型得到的吸积盘结构与三维模拟结果吻合得很好。我们的模型是一个有用的工具，为进一步模拟化学，辐射传输和行星形成的原行星盘。
We investigate the formation process of self-gravitating protoplanetary disks in unmagnetized molecular clouds. The angular momentum is redistributed by the action of gravitational torques in the massive disk during its early formation. We develop a simplified one-dimensional accretion disk model that takes into account the infall of gas from the envelope onto the disk and the transfer of angular momentum in the disk with an effective viscosity. First we evaluate the gas accretion rate from the cloud core onto the disk by approximately estimating the effects of gas pressure and gravity acting on the cloud core. We formulate the effective viscosity as a function of the Toomre Q parameter that measures the local gravitational stability of the rotating thin disk. We use a function for viscosity that changes sensitively with Q when the disk is gravitationally unstable. We find a strong self-regulation mechanism in the disk evolution. During the formation stage of protoplanetary disks, the evolution of the surface density does not depend on the other details of the modeling of effective viscosity, such as the prefactor of the viscosity coefficient. Next, to verify our model, we compare the time evolution of the disk calculated with our formulation with that of three-dimensional hydrodynamical simulations. The structures of the resultant disks from the one-dimensional accretion disk model agree well with those of the three-dimensional simulations. Our model is a useful tool for the further modeling of chemistry, radiative transfer, and planet formation in protoplanetary disks.