Wind morphology around cool evolved stars in binaries
Wind morphology around cool evolved stars in binaries
复制标题
双星中冷演化恒星周围的风形态
DOI：
10.1051/0004-6361/202037492
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发表时间：
2020
影响因子：
6.5
通讯作者：
R. Keppens
中科院分区：
文献类型：
--
作者：
I. Mellah;J. Bolte;L. Decin;W. Homan;R. Keppens
上下文低质量和中等质量恒星的晚期演化阶段受到其质量损失率的强烈限制，这比主序期间高出几个数量级。这些冷膨胀恒星周围的风经常表现出非球形对称性，这被认为是由于一个看不见的伴星围绕着施主星星旋转。流出物中留下的印记携带着关于伴星的信息，以及这些尘埃驱动风的发射机制。
目标。我们研究了环双星的信封的形态，并确定周围的同伴风捕获磁盘的形成条件。长期的轨道变化引起的质量损失和质量转移到次要的也进行了研究。我们特别注意富氧，即缓慢加速，外流，以寻找系统之间的差异，周围的风动力学的碳和氧丰富的渐近巨星分支（AGB）的明星。
方法.我们提出了一个模型的基础上的参数化的风加速度和一个减少的无量纲参数的数量连接风形态的基本二元系统的属性。由于高性能的代码MPI-AMRVAC，我们运行了一个广泛的72个三维流体动力学模拟的逐步加速风传播的罗氏潜力的质量损失的演变星星在轨道上的主序星伴侣。我们使用的高度自适应的网格细化使我们能够解析次级附近的流动结构，其中形成弓形激波、外流和风捕获盘，以及多达40个轨道分离，其中螺旋臂、弧和赤道密度增强发展。
结果当伴星被风深深吞没时，富氧AGB星周围较低的终端风速和更渐进的风加速度使它们比富碳AGB星更容易显示出更多的扰动外流，伴星周围的盘状结构，以及集中在轨道平面上的风。在这些配置中，大部分的风被伴星捕获，如果施主星星的质量至少是伴星的几倍，这将导致伴星的轨道在质量损失时间尺度上显著收缩。在其他情况下，轨道间隔的增加是可以预期的，尽管速度低于施主星星的质量损失率。如果伴星的质量至少是施主星星质量的十分之一，它就可以将轨道平面上的风压缩到很远的距离。
结论.我们计算的模型网格涵盖了广泛的配置：我们改变终端风速相对于轨道速度，周围的尘埃凝聚区的延伸相对于轨道分离的冷演化星星，和质量比，我们认为一个富碳和富氧的施主星星。它提供了一个方便的参考框架，以解释周围的冷演化恒星外流的高分辨率地图。
Context. The late evolutionary phase of low- and intermediate-mass stars is strongly constrained by their mass-loss rate, which is orders of magnitude higher than during the main sequence. The wind surrounding these cool expanded stars frequently shows nonspherical symmetry, which is thought to be due to an unseen companion orbiting the donor star. The imprints left in the outflow carry information about the companion and also the launching mechanism of these dust-driven winds.
Aims. We study the morphology of the circumbinary envelope and identify the conditions of formation of a wind-captured disk around the companion. Long-term orbital changes induced by mass loss and mass transfer to the secondary are also investigated. We pay particular attention to oxygen-rich, that is slowly accelerating, outflows in order to look for systematic differences between the dynamics of the wind around carbon and oxygen-rich asymptotic giant branch (AGB) stars.
Methods. We present a model based on a parametrized wind acceleration and a reduced number of dimensionless parameters to connect the wind morphology to the properties of the underlying binary system. Thanks to the high performance code MPI-AMRVAC, we ran an extensive set of 72 three-dimensional hydrodynamics simulations of a progressively accelerating wind propagating in the Roche potential of a mass-losing evolved star in orbit with a main sequence companion. The highly adaptive mesh refinement that we used, enabled us to resolve the flow structure both in the immediate vicinity of the secondary, where bow shocks, outflows, and wind-captured disks form, and up to 40 orbital separations, where spiral arms, arcs, and equatorial density enhancements develop.
Results. When the companion is deeply engulfed in the wind, the lower terminal wind speeds and more progressive wind acceleration around oxygen-rich AGB stars make them more prone than carbon-rich AGB stars to display more disturbed outflows, a disk-like structure around the companion, and a wind concentrated in the orbital plane. In these configurations, a large fraction of the wind is captured by the companion, which leads to a significant shrinking of the orbit over the mass-loss timescale, if the donor star is at least a few times more massive than its companion. In the other cases, an increase of the orbital separation is to be expected, though at a rate lower than the mass-loss rate of the donor star. Provided the companion has a mass of at least a tenth of the mass of the donor star, it can compress the wind in the orbital plane up to large distances.
Conclusions. The grid of models that we computed covers a wide scope of configurations: We vary the terminal wind speed relative to the orbital speed, the extension of the dust condensation region around the cool evolved star relative to the orbital separation, and the mass ratio, and we consider a carbon-rich and an oxygen-rich donor star. It provides a convenient frame of reference to interpret high-resolution maps of the outflows surrounding cool evolved stars.
红巨星 R Sculptoris 的热脉冲周期中意外的大量质量损失
影响因子：
64.8
作者：
Maercker;Mohamed;Vlemmings;Ramstedt;Groenewegen;Humphreys;Kerschbaum;Lindqvist;Olofsson;Paladini;Wittkowski;de Gregorio-Monsalvo
通讯作者：
de Gregorio-Monsalvo
影响因子：
6.3
作者：
O. De Marco;R. Izzard
通讯作者：
O. De Marco;R. Izzard
Magritte，一个用于 3D 辐射传输的现代软件库：I. 非 LTE 原子和分子线建模
影响因子：
4.8
作者：
De Ceuster F
通讯作者：
De Ceuster F