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arXiv 1306.4333astro-ph.SR
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环双星盘II中的波状翘曲传播。应用于KH 15 D

Wave-like warp propagation in circumbinary discs II. Application to KH 15D

Giuseppe Lodato, Stefano Facchini

备注：
8 pages, 3 figures, accepted for publication in MNRAS
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摘要：

KH 15 D是一个具有特殊光变曲线的原恒星双星系统。为了模拟它，一个狭窄的环双星旋进盘已经被调用，但一个合适的动力学模型从来没有被开发出来。在本文中，我们分析解决的问题，这样的磁盘是否可以刚性进动KH 15 D，我们的进动周期的主要参数的系统。然后，我们模拟光盘的动力学，使用一个1D模型开发的配套文件，这样的翘曲传播到光盘作为弯曲波，这是预期的情况下，原恒星盘。这种方法的有效性已被证实，通过比较其结果与全三维SPH模拟扩展光盘。在目前的情况下，我们使用这个一维代码来模拟在一个狭窄的光盘翘曲的传播。如果圆盘的内部截断半径由二元潮汐力矩设定为{ \sim } 1 AU，我们发现圆盘应该延伸到6-10 AU（取决于模型），因此比以前建议的更宽。我们的模拟表明，这样的光盘达到几乎稳定的状态，然后作为一个刚体进动。盘显示非常小的翘曲，具有随着半径增加的倾斜倾斜，以保持盘相对于二进制扭矩处于平衡。然而，对于这种较宽的盘，粘性的存在导致倾斜在{ \approx } 3000（α/0.05）^（-1）年的时间尺度上的长期衰减，其中α是盘的粘性参数。第三个天体（如行星）的存在，大约在10天文单位的轨道上运行，可能同时解释了圆盘的外部截断和长时间的倾斜。

英文摘要：

KH 15D is a protostellar binary system that shows a peculiar light curve. In order to model it, a narrow circumbinary precessing disc has been invoked, but a proper dynamical model has never been developed. In this paper, we analytically address the issue of whether such a disc can rigidly precess around KH 15D, and we relate the precessional period to the main parameters of the system. Then, we simulate the disc's dynamics by using a 1D model developed in a companion paper, such that the warp propagates into the disc as a bending wave, which is expected to be the case for protostellar discs. The validity of such an approach has been confirmed by comparing its results with full 3D SPH simulations on extended discs. In the present case, we use this 1D code to model the propagation of the warp in a narrow disc. If the inner truncation radius of the disc is set by the binary tidal torques at {\sim} 1 AU, we find that the disc should extend out to 6-10 AU (depending on the models), and is therefore wider than previously suggested. Our simulations show that such a disc does reach an almost steady state, and then precesses as a rigid body. The disc displays a very small warp, with a tilt inclination that increases with radius in order to keep the disc in equilibrium against the binary torque. However, for such wider discs, the presence of viscosity leads to a secular decay of the tilt on a timescale of {\approx} 3000 (α/0.05)^(-1) years, where α is the disc viscosity parameter. The presence of a third body (such as a planet), orbiting at roughly 10 AU might simultaneously explain the outer truncation of the disc and the maintenance of the tilt for a prolonged time.

机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。

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