3D simulations of Betelgeuse’s bow shock
3D simulations of Betelgeuse’s bow shock
复制标题
参宿四弓形激波的 3D 模拟
DOI：
10.1051/0004-6361/201118002
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发表时间：
2011
影响因子：
6.5
通讯作者：
N. Langer
中科院分区：
文献类型：
--
作者：
S. Mohamed;J. Mackey;N. Langer
参宿四，猎户座中明亮、凉爽的红色超巨星，相对于当地的星际介质以超音速运动。星星发出强大的恒星风，与这种介质碰撞，形成彗星状结构，弓形激波，指向运动方向。我们提出了第一个三维流体动力学模拟的形成和演变的参宿四的弓激波。这些模型包括真实的低温冷却，并涵盖了一系列合理的星际介质密度为0.3-1.9 cm−3，恒星速度为28-73 km s−1。我们发现，由于瑞利-泰勒或开尔文-亥姆霍兹不稳定性的增长，弓形激波的流动动力学和形态有很大的不同。前者主导的模型与缓慢的恒星速度导致cluerical弓激波子结构，而后者产生更平滑，更分层的子结构中的快速模型。如果弓形激波壳层的质量很低，就像AKARI光度（103 × 10−3 M）所暗示的那样，那么参宿四的弓形激波是非常年轻的，不太可能达到稳定状态。弓形激波壳的圆形特性与这一结论是一致的。因此，我们的结果表明参宿四最近才进入红超巨星阶段。
Betelgeuse, the bright, cool red supergiant in Orion, is moving supersonically relative to the local interstellar medium. The star emits a powerful stellar wind that collides with this medium, forming a cometary structure, a bow shock, pointing in the direction of motion. We present the first 3D hydrodynamic simulations of the formation and evolution of Betelgeuse’s bow shock. The models include realistic low-temperature cooling and cover a range of plausible interstellar medium densities of 0.3–1.9 cm−3 and stellar velocities of 28–73 km s−1. We show that the flow dynamics and morphology of the bow shock differ substantially because of the growth of Rayleigh-Taylor or Kelvin-Helmholtz instabilities. The former dominate the models with slow stellar velocities resulting in a clumpy bow shock substructure, whereas the latter produce a smoother, more layered substructure in the fast models. If the mass in the bow shock shell is low, as seems to be implied by the AKARI luminosities (∼3 × 10−3 M ), then Betelgeuse’s bow shock is very young and is unlikely to have reached a steady state. The circular nature of the bow shock shell is consistent with this conclusion. Thus, our results suggest that Betelgeuse only entered the red supergiant phase recently.