Accretion Disks in Pre-Planetary Nebulae
Accretion Disks in Pre-Planetary Nebulae
复制标题
前行星状星云中的吸积盘
DOI：
10.1086/307827
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发表时间：
1999
期刊：
影响因子：
--
通讯作者：
J. A. Lopez
中科院分区：
文献类型：
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作者：
M. Reyes;J. A. Lopez
许多行星状星云(PN)显示出平行的高速流出或喷流。这些流体动力学结构不能很容易地适应于后渐近巨星分支恒星演化的经典模型，理解它们已经成为PN研究中的一个热门问题。解释PNS中喷流存在的一种方法是援引吸积盘的存在，这可能会为外流的准直和驱动设定条件。这项工作详细研究了可能导致罗氏瓣溢出(RLOF)的双星系统类型以及作为共同包络演化结果的吸积盘的形成，并探索了这种盘的预期基本物理结构。分析结果显示，二元系统的组成受到很大的限制，这些系统在吸积到主星上时可以形成盘。结果表明，对于包络质量为2-3M☉、包络质量为0.6M☉的初级渐近巨型分支(AGB)核，具有M2≳0.08M☉和初始分离ai≳200R☉的次级核不会导致RLOF。对于确实导致RLOF的系统，这是在轨道分离<；2 R☉时实现的。我们还发现，M2≳为0.08M☉的次级粒子的动态稳定传质不会导致盘的形成，因为圆化半径位于AGB核的表面以下。在动态不稳定的传质过程之后，只有较低的质量同伴才可能导致盘的形成。在合理的简化假设下，我们估计了由此产生的吸积盘的性质和演化，并讨论了它们在驱动准直流出中的潜在作用。
A number of planetary nebulae (PNs) exhibit collimated, high-velocity outflows or jets. These hydrodynamical structures cannot be easily accommodated within the classical models of the evolution of post-asymptotic giant branch stars, and understanding them has become a topical problem in PN research. One way to explain the existence of jets in PNs has been to invoke the presence of accretion disks, which would presumably set the conditions for the collimation and driving of the outflows. This work investigates in detail the type of binary systems that are likely to lead to Roche-lobe overflow (RLOF) and the formation of accretion disks as a consequence of common-envelope evolution, and explores the expected basic physical structure of such disks. The results of the analysis show substantial restrictions on the composition of binary systems that can form a disk upon accretion onto the primary. Typically, it is found that for a primary asymptotic giant branch (AGB) core of 0.6 M☉ and envelope mass of 2-3 M☉, secondaries with M2 ≳ 0.08 M☉ and initial separation ai ≳ 200 R☉ will not lead to RLOF. For systems that do lead to RLOF, this is achieved at orbital separations <2 R☉. We also find that dynamically stable mass transfer from secondaries with M2 ≳ 0.08 M☉ does not lead to disk formation, since the circularization radius lies below the surface of the AGB core. Only lower mass companions, after a dynamically unstable mass transfer process, may lead to disk formation. Under reasonable simplifying assumptions, we estimate the resulting accretion disk properties and evolution and discuss their potential role in driving collimated outflows.