Modelling circumbinary gas flows in close T Tauri binaries
Modelling circumbinary gas flows in close T Tauri binaries
复制标题
模拟金牛座 T 型双星周围的气体流动
DOI：
10.1111/j.1365-2966.2011.18339.x
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发表时间：
2011
影响因子：
4.8
通讯作者：
A. Pepli'nski
中科院分区：
文献类型：
--
作者：
Miguel de Val;G. Gahm;H. C. Stempels;A. Pepli'nski
年轻的封闭双星在周围的环双星吸积盘中打开了中心的间隙，但是恒星成分仍然可能从穿过间隙的气体中获得质量。目前还不清楚这个过程是如何运作的，以及恒星成分是如何受到这种流入的影响的。我们的主要目标是研究在紧密的金牛座双星系统中气体吸积是如何发生和演变的。特别是，我们模拟了两个接近的金牛座T双星V4046 Sgr和DQ Tau周围的吸积流，尽管它们的轨道特征非常不同，但它们都显示出发射线的周期性变化。为了推导出环二元材料的密度和速度图，我们采用了二维流体力学模拟和局部等温状态方程。在与系统旋转的框架中经过几个轨道后，流型变得准稳定。气体通过旋转的拉格朗日点流过星周间隙，局部星周盘在两部分周围形成。螺旋密度模式在环双星盘中发展，有效地传递角动量。质量优先流向主星，它的星周盘比次级星周围的盘质量更大。我们还比较了导出的密度分布与观测到的线廓变异性。追踪中央空腔内气体流动的谱线变异性与在Sgr V4046中观测到的相应谱线变异性有明显的相似性，但只有在排除局部星周盘辐射的情况下才如此。在靠近恒星的地方，正常的磁层吸积可能占主导地位，而在更远的地方，这里概述的动态吸积过程占主导地位。恒星吸积速率的周期性变化可以解释在DQ Tau等偏心星系中观测到的线发射爆发。
Young close binaries open central gaps in the surrounding circumbinary accretion disc, but the stellar components may still gain mass from gas crossing through the gap. It is not well understood how this process operates and how the stellar components are affected by such inflows. Our main goal is to investigate how gas accretion takes place and evolves in close T Tauri binary systems. In particular, we model the accretion flows around two close T Tauri binaries, V4046 Sgr and DQ Tau, both showing periodic changes in emission lines, although their orbital characteristics are very different. In order to derive the density and velocity maps of the circumbinary material, we employ two-dimensional hydrodynamic simulations with a locally isothermal equation of state. The flow patterns become quasi-stable after a few orbits in the frame corotating with the system. Gas flows across the circumbinary gap through the corotating Lagrangian points, and local circumstellar discs develop around both components. Spiral density patterns develop in the circumbinary disc that transport angular momentum efficiently. Mass is preferentially channelled towards the primary and its circumstellar disc is more massive than the disc around the secondary. We also compare the derived density distribution to observed line profile variability. The line profile variability tracing the gas flows in the central cavity shows clear similarities with the corresponding observed line profile variability in V4046 Sgr, but only when the local circumstellar disc emission was excluded. Closer to the stars normal magnetospheric accretion may dominate, while further out the dynamic accretion process outlined here dominates. Periodic changes in the accretion rates on to the stars can explain the outbursts of line emission observed in eccentric systems such as DQ Tau.
影响因子：
3.2
作者：
V. Mannings;A. Boss;S. Russell
通讯作者：
V. Mannings;A. Boss;S. Russell