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arXiv 1307.4286astro-ph.EP
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双星辐射盘的三维模拟

Three-dimensional modeling of radiative disks in binaries

Giovanni Picogna, Francesco Marzari

摘要:

双星中的星周盘受到伴星引力的扰动,导致盘的形态发生显著的变化。螺旋波由于同伴潮汐力也发展在垂直方向上,并影响磁盘的温度分布。这些效应可能对行星形成的过程产生重大影响。我们进行三维数值模拟的磁盘在二进制与不同的初始动力学配置和物理参数。我们的目标是研究它们的进化和它们生长行星的倾向。我们使用改进版本的SPH代码VINE修改,以更好地考虑动量和能量守恒。能量方程包括一个通量限制的辐射转移算法和磁盘冷却是通过“边界粒子”。我们模拟了一个由恒星/星盘+恒星/星盘组成的系统,其中次级恒星(和相对的星盘)的质量小于主星。对不同的双星分离度和盘密度值进行的数值模拟表明,盘的形态受到伴随扰动的显著影响。当恒星接近它们的近心时,会产生螺旋激波。强烈的水跃发生在激波前沿,产生破碎波和两个圆盘之间的一致质量流,显著加热它们。高的气体温度可以通过向外移动“雪线”来防止冰冷凝。水力跃变可能减缓甚至停止粉尘凝聚过程。在远心处,这些扰动减小,盘冷却下来,偏心减小。水力跃变、盘加热和质量交换的强度取决于二元分离,并且对于较大的半长轴,潮汐螺旋图案大幅减小。

英文摘要:

Circumstellar disks in binaries are perturbed by the companion gravity causing significant alterations of the disk morphology. Spiral waves due to the companion tidal force also develop in the vertical direction and affect the disk temperature profile. These effects may significantly influence the process of planet formation. We perform 3D numerical simulations of disks in binaries with different initial dynamical configurations and physical parameters. Our goal is to investigate their evolution and their propensity to grow planets. We use an improved version of the SPH code VINE modified to better account for momentum and energy conservation. The energy equation includes a flux--limited radiative transfer algorithm and the disk cooling is obtained via "boundary particles". We model a system made of star/disk + star/disk where the secondary star (and relative disk) is less massive than the primary. The numerical simulations performed for different values of binary separation and disk density show that the disk morphology is substantially affected by the companion perturbations. Trailing spiral shock waves develop when the stars approach their pericenter. Strong hydraulic jumps occur at the shock front creating breaking waves and a consistent mass stream between the two disks, significantly heating them. The high gas temperature may prevent the ice condensation by moving outward the "snow line". The hydraulic jumps may slow down or even halt the dust coagulation process. At apocenter these perturbations are reduced and the disks are cooled down and less eccentric. The strength of the hydraulic jumps, disk heating, and mass exchange depends on the binary separation, and for larger semi-major axes, the tidal spiral pattern is substantially reduced.

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