关于大质量恒星的星周介质及其在GRB观测中的表现
On the circumstellar medium of massive stars and how it may appear in GRB observations
摘要：
大质量恒星在其演化过程中失去了其原始质量的很大一部分。这些恒星风根据恒星特征的结果参数塑造周围的介质，随着恒星的演化而变化，导致永久和临时的特征，可以用来限制祖星的演化。由于长伽马射线暴（GRB）被认为起源于大质量恒星，因此星周介质（CSM）的特征应该在GRB信号中被观测到。这可以直接发生，因为GRB喷流的特性会被它碰撞的介质改变，也可以间接发生，因为GRB只能通过围绕每个大质量恒星的扩展的星周气泡来观察。我们使用计算机模拟来描述可以在大质量恒星附近发现的拱星特征，并讨论它们是否以及如何出现在伽玛射线暴观测中。具体来说，我们做了一个快速旋转，化学近均匀的恒星，这是代表一个伽玛射线暴祖先候选模型的星周环境的流体动力学模型。模拟显示，恒星产生了一个大规模的冲击风物质气泡，在一个膨胀的外壳中席卷了星际介质。在这个气泡中，由于恒星风的变化，临时的星周壳，团块和空洞被创造出来。当恒星走到生命的尽头时，这些暂时的特征大部分都消失了，留下了一个高度动荡的星周气泡。将同一颗恒星放置在高密度环境中可以简化CSM的演化，因为更封闭的气泡阻止了一些临时结构的形成。
英文摘要：
Massive stars lose a large fraction of their original mass over the course of their evolution. These stellar winds shape the surrounding medium according to parameters that are the result of the characteristics of the stars, varying over time as the stars evolve, leading to both permanent and temporary features that can be used to constrain the evolution of the progenitor star. Because long Gamma-Ray Bursts (GRBs) are thought to originate from massive stars, the characteristics of the circumstellar medium (CSM) should be observable in the signal of GRBs. This can occur directly, as the characteristics of the GRB-jet are changed by the medium it collides with, and indirectly because the GRB can only be observed through the extended circumstellar bubble that surrounds each massive star. We use computer simulations to describe the circumstellar features that can be found in the vicinity of massive stars and discuss if, and how, they may appear in GRB observations. Specifically, we make hydrodynamical models of the circumstellar environment of a rapidly rotating, chemically near-homogeneous star, which is represents a GRB progenitor candidate model. The simulations show that the star creates a large scale bubble of shocked wind material, which sweeps up the interstellar medium in an expanding shell. Within this bubble, temporary circumstellar shells, clumps and voids are created as a result of changes in the stellar wind. Most of these temporary features have disappeared by the time the star reaches the end of its life, leaving a highly turbulent circumstellar bubble behind. Placing the same star in a high density environment simplifies the evolution of the CSM as the more confined bubble prohibits the formation of some of the temporary structures.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
