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arXiv 1609.02602astro-ph.SR
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Angular Momentum输运在建立吸积率-原恒星质量关联中的作用

The Role of Angular Momentum Transport in Establishing the Accretion Rate--Protostellar Mass Correlation

Alexander L. DeSouza, Shantanu Basu

备注：
23 pages (manuscript), 8 figures
发表信息：
New Astronomy, pp. 113-121 (2017)
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摘要：

我们模型的质量吸积率$\dot{M}$恒星质量$M_*$的相关性，已推断出从中间到上质量的金牛座T星的观测-这是$\dot{M} \propto M_*^{1.3 \pm 0.3}$。我们解释这种相关性的框架内的静态磁盘的演变，吸积主要是由引力作用在大部分的质量和体积的磁盘扭矩驱动。在我们的一维模型中，根据Toomre的$Q$准则，引力驱动力矩的作用引起圆盘内的应力。我们不模拟热的内部亚AU尺度区域的磁盘可能是稳定的，根据这一标准，并呼吁其他机制，以消除或重新分配角动量，并允许吸积到恒星上。我们的模型的优点是同意大规模的角度平均值从更复杂的非轴对称计算。该模型盘过渡从早期阶段（占主导地位的初始条件继承的突发模式的吸积）到后来的自相似模式，其特征在于一个陡峭的时间下降$\dot{M}$。该模型有效地再现了质量吸积率的传播，已观察到的原恒星对象的$0.2\,\mbox{M}_\odot \le M_* \le 3.0\,\mbox{M}_\odot$，如那些发现在$ρ$蛇夫座和金牛座恒星形成地区。然后，我们比较现实的采样人口的年轻恒星物体产生我们的模型，他们的观测同行。我们发现这些人口统计上是一致的，我们认为这是引力矩的作用的证据在静止的原恒星盘的后期演化。

英文摘要：

We model the mass accretion rate $\dot{M}$ to stellar mass $M_*$ correlation that has been inferred from observations of intermediate to upper mass T Tauri stars---that is $\dot{M} \propto M_*^{1.3 \pm 0.3}$. We explain this correlation within the framework of quiescent disk evolution, in which accretion is driven largely by gravitational torques acting in the bulk of the mass and volume of the disk. Stresses within the disk arise from the action of gravitationally driven torques parameterized in our 1D model in terms of Toomre's $Q$ criterion. We do not model the hot inner sub-AU scale region of the disk that is likely stable according to this criterion, and appeal to other mechanisms to remove or redistribute angular momentum and allow accretion onto the star. Our model has the advantage of agreeing with large-scale angle-averaged values from more complex nonaxisymmetric calculations. The model disk transitions from an early phase (dominated by initial conditions inherited from the burst mode of accretion) into a later self-similar mode characterized by a steeper temporal decline in $\dot{M}$. The models effectively reproduce the spread in mass accretion rates that have been observed for protostellar objects of $0.2\,\mbox{M}_\odot \le M_* \le 3.0\,\mbox{M}_\odot$, such as those found in the $ρ$ Ophiuchus and Taurus star forming regions. We then compare realistically sampled populations of young stellar objects produced by our model to their observational counterparts. We find these populations to be statistically coincident, which we argue is evidence for the role of gravitational torques in the late time evolution of quiescent protostellar disks.

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