Two-Dimensional Accretion Disk Models : Inner Accretion Disks of FU Orionis Objects
Two-Dimensional Accretion Disk Models : Inner Accretion Disks of FU Orionis Objects
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二维吸积盘模型：FU Orionis 天体的内部吸积盘
DOI：
10.1093/pasj/49.6.679
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发表时间：
1997
影响因子：
2.3
通讯作者：
S. Sakashita
中科院分区：
文献类型：
--
作者：
T. Okuda;M. Fujita;S. Sakashita
为了研究几何厚吸积盘的结构和动力学，我们进行了二维轴对称计算，通过求解一组完全非线性流体动力学方程耦合辐射输运。以FU Orionis天体的内吸积盘为研究对象，得到了几何厚度的准稳态吸积盘，它被光学厚度薄、稀薄、高温的大气层所包围。对于一个非旋转的中心星星，我们得到了一个相当广泛的边界层之间的中心星星和吸积盘。在几百个开普勒轨道周期内建立准稳定盘之后，进一步的连续吸积在恒星表面上方形成一个静态和致密的包层。结果，光度在长时间尺度上逐渐减小，因为引力势阱变浅。另一方面，对于破碎角速度为0.8的快速旋转星星，对流形成在恒星表面附近，而不是一个广泛的边界层和静态包络。当增加的对流质量通量达到一个临界值时，在稀薄极区形成高速喷流，光度急剧增加。爆发的亮度持续几个月，大约每八个月重复一次。
To examine the structure and dynamics of a geometrically thick accretion disk, we performed two-dimensional axisymmetric calculations by solving a set of fully non-linear hydrodynamic equations coupled with radiation transport. Focusing on the inner accretion disks of FU Orionis objects, we obtained geometrically thick and quasi-steady accretion disks which are surrounded by an optically thin, rarefied and high-temperature atmosphere. For a non-rotating central star, we obtained a rather broad boundary layer between the central star and the accretion disk. After the quasi-steady disk is established within a few hundred Keplerian orbital periods, further continuous accretion forms a static and dense envelope just above the stellar surface. As a result, the luminosity gradually decreases on a long time scale, because the gravitational potential well becomes shallow. On the other hand, for a rapidly rotating star with 0.8 breakup angular velocity, convective flow is formed near to the stellar surface instead of a broad boundary layer and a static envelope. As soon as the increasing convective mass flux attains a critical value, a high-velocity jet is formed in the rarefied polar region and the luminosity increases sharply. The bursting luminosity lasts for a few months and recurs approximately every eight months.