Gas Accretion in Protobinary and Evolution of Binary

原恒星和年轻恒星的特征是它们的活跃气体吸积。由于大多数原恒星都是双星和聚星的成员，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，这些研究在一定程度上受到技术困难的限制。采用嵌套网格技术，成功地模拟了双星系统中的气体吸积。它们以高空间分辨率同时覆盖了环双星盘和拱星盘。我们发现在环双星盘中激发出成对的螺旋激波。一对螺旋激波与双星同步旋转，而其他对旋转得更慢。当共转螺旋激波超前时，气体密度在L2点附近上升，流入双星的流量增加。其他激波对之间的相互作用引起环双星盘内的气体吸积。在高空间分辨率的模拟中还显示，湍流在L1点附近产生。作为相关的工作，我们进行了模拟的二元形成。我们还开发了具有更高空间分辨率的AMR程序和强磁流体激波的数值计算方案，为今后的研究提供了参考。

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.