Gas Accretion in Protobinary and Evolution of Binary

原恒星和年轻恒星的特征是它们活跃的气体吸积。由于大多数原恒星是双星和多星的成员，因此评估它们的伴星在气体吸积中的作用是很重要的。然而，由于技术上的困难，这些研究非常有限。利用嵌套网格技术，我们成功地模拟了双星系统中的气体吸积。它们同时覆盖了星周盘和星周盘，具有很高的空间分辨率。我们发现在环双星盘中有一对螺旋激波被激发。一对螺旋激波与双星旋转，而另一对则旋转得更慢。当旋转螺旋激波领先于其他激波时，气体密度在L2点附近上升，进入双星的气流增加。其他激波对之间的相互作用引起了环双星盘内的气体吸积。高空间分辨率的模拟结果也表明，湍流在L1点附近出现。作为相关工作，我们进行了双星形成的模拟。我们还开发了具有更高空间分辨率的AMR代码和强MHD激波的数值格式，以供将来的研究。

Protostears and young stellar objects are characterized by their active gas accretion. Since most protostars are members of binary and multiple stars, it is important to assess the role of their companions on the gas accretion. However, the studies are very limited in part by technical difficulties. By employing nested grid technique we have succeeded in simulations of gas accretion in a binary system. They cover both the circumbinary disk and circumstellar disks simultaneously with high spatial resolution. We have found that pairs of spiral shock waves are excited in the circumbinary disk. A pair of the spiral shocks corotates with the binary while the other pairs rotate more slowly. When the corotating spiral shock waves get ahead of the others, the gas density rises near L2 point and the inflow onto the binary increases. Interaction between the other pairs of shock waves induce gas accretion within the circumbinary disk. It is also shown in simulations of high spatial resolution that the turbulence arises near L1 point. As related works we have performed simulations of binary formation. We also developed AMR code capable for still higher spatial resolution and numerical scheme for strong MHD shock waves for future studies.