Evolution of protoplanetary disks: Constraints from DM Tauri and GM Aurigae
Evolution of protoplanetary disks: Constraints from DM Tauri and GM Aurigae
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DOI：
10.1051/0004-6361:20041905
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发表时间：
2005-06
影响因子：
6.5
通讯作者：
R. Hueso;T. Guillot
中科院分区：
文献类型：
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作者：
R. Hueso;T. Guillot
我们提出了一个一维模型的形成和粘性演化的原行星盘。早期磁盘的形成被模拟为等温分子云的引力坍缩的结果。圆盘的粘性演化根据湍流的两种参数化进行积分：经典的α表示和β参数化，代表由克卜勒剪切驱动的非线性湍流。我们将该模型应用于DM Tau和GM Aur，两个经典的T-Tauri星，具有相对较好的特征盘，检索其表面密度随时间的演化。我们进行了系统的蒙特-卡罗探索的参数空间（即α-β参数的值，以及在分子云的温度和旋转速率），以找到与所观察到的磁盘表面密度分布，星星和磁盘的质量，年龄和目前的吸积率相一致的值。我们发现DM Tau的观测值需要0.001 <α< 0. 1o r 2 × 10 −5 <β< 5 × 10 −4。对于GM Aur，我们发现湍流粘滞系数为4 × 10 −4 <α< 0.01或2 × 10 −6 <β< 8 × 10 −5。这些相对较大的数值表明，在大于10 × 10 Au的距离上存在有效的湍流扩散机制。这将与金牛座T星吸积率随年龄变化的研究进行比较，后者主要探测内部盘，但也产生α = 0.01的值。我们表明，在大的轨道距离负责湍流扩散的机制最有可能不能对流，因为它在低光学深度的抑制。
We present a one-dimensional model of the formation and viscous evolution of protoplanetary disks. The formation of the early disk is modeled as the result of the gravitational collapse of an isothermal molecular cloud. The disk’s viscous evolution is integrated according to two parameterizations of turbulence: the classical α representation and a β parameterization, representative of non-linear turbulence driven by the keplerian shear. We apply the model to DM Tau and GM Aur, two classical T-Tauri stars with relatively well-characterized disks, retrieving the evolution of their surface density with time. We perform a systematic Monte-Carlo exploration of the parameter space (i.e. values of the α-β parameters, and of the temperature and rotation rate in the molecular cloud) to find the values that are compatible with the observed disk surface density distribution, star and disk mass, age and present accretion rate. We find that the observations for DM Tau require 0.001 <α< 0. 1o r 2 × 10 −5 <β< 5 × 10 −4 . For GM Aur, we find that the turbulent viscosity is such that 4 × 10 −4 <α< 0.01 or 2 × 10 −6 <β< 8 × 10 −5 .T hese relatively large values show that an efficient turbulent diffusion mechanism is present at distances larger than ∼10 AU. This is to be compared to studies of the variations of accretion rates of T-Tauri stars versus age that mostly probe the inner disks, but also yield values of α ∼ 0.01. We show that the mechanism responsible for turbulent diffusion at large orbital distances most probably cannot be convection because of its suppression at low optical depths.