The formation and evolution of wind-capture discs in binary systems
The formation and evolution of wind-capture discs in binary systems
复制标题
双星系统中捕风盘的形成与演化
DOI：
10.1093/mnras/stt725
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发表时间：
2012
影响因子：
4.8
通讯作者：
E. Blackman
中科院分区：
文献类型：
--
作者：
M. Huarte;J. Carroll;J. Nordhaus;A. Frank;E. Blackman
我们研究通过双星系统中的风捕获形成的吸积盘的形成、演化和物理特性。使用 AMR 代码 AstroBEAR，我们进行了高分辨率 3D 模拟，模拟了共转系中的次级恒星质量，因为它绕着产生风的 AGB 初级恒星运行。我们首先基于邦迪-霍伊尔流的考虑得出一个解决标准，必须满足该标准才能正确解决次级行星周围吸积盘的形成问题。然后，我们比较具有三个不同轨道半径（Ro = 10、15、20AU）的双星的模拟。在所有三种情况下都会形成圆盘，但是圆盘的大小以及最重要的是它的吸积率随着轨道半径的减小而减小。此外，随着二元分离的增加，盘内材料的轨道运动的形状变得越来越椭圆。流动稍微不稳定，观察到弓形激波周围有“颤动”。经过几次双星轨道之后，圆盘通常与轨道平面很好地对齐。我们没有观察到任何大规模、剧烈的不稳定性的存在（例如触发器模式）。此外，首次观察到向次级风聚集的风分量具有涡管状结构，而不是之前认为的柱状结构。在AGB双星系统（可能是前行星状星云和行星状星云的前身）的背景下，我们发现，如果伴星是主序星，则所选轨道间隔处的风吸积率通常太小，无法产生在这些系统中观察到的最强大的流出量，但如果伴星是白矮星，则几乎没有能力。许多更强大的 PPN 和 PN 可能涉及比此处考虑的更接近的二进制文件。结果还证明了与所有捕风双系统广泛相关的原理。
We study the formation, evolution and physical properties of accretion disks formed via wind capture in binary systems. Using the AMR code AstroBEAR, we have carried out high resolution 3D simulations that follow a stellar mass secondary in the corotating frame as it orbits a wind producing AGB primary. We first derive a resolution criteria, based on considerations of Bondi-Hoyle flows, that must be met in order to properly resolve the formation of accretion disks around the secondary. We then compare simulations of binaries with three different orbital radii (Ro =10, 15, 20AU). Disks are formed in all three cases, however the size of the disk and, most importantly, its accretion rate decreases with orbital radii. In addition, the shape of the orbital motions of material within the disk becomes increasingly elliptical with increasing binary separation. The flow is mildly unsteady with “fluttering” around the bow shock observed. The disks are generally well aligned with the orbital plane after a few binary orbits. We do not observe the presence of any large scale, violent instabilities (such as the flip-flop mode). For the first time, moreover, it is observed that the wind component that is accreted towards the secondary has a vortex tube-like structure, rather than a column-like one as it was previously thought. In the context of AGB binary systems that might be precursors to Pre-Planetary and Planetary Nebula, we find that the wind accretion rates at the chosen orbital separations are generally too small to produce the most powerful outflows observed in these systems if the companions are main sequence stars but marginally capable if the companions are white dwarfs. It is likely that many of the more powerful PPN and PN involve closer binaries than the ones considered here. The results also demonstrate principles of broad relevance to all wind-capture binary systems.