大质量恒星包层的三维特性

IF 3.2 Q2 ASTRONOMY & ASTROPHYSICS
Galaxies Pub Date : 2023-10-11 DOI:10.3390/galaxies11050105
Yan-Fei Jiang
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引用次数: 0

摘要

在本文中,我们回顾了目前基于三维(3D)辐射流体动力学模拟对大质量恒星外包膜结构的理解。本文简要总结了当恒星光度接近Eddington值时,建立流体静力一维(1D)恒星演化模型的基本问题。在质量范围从13M⊙到80M⊙的三维辐射流体动力学模拟中,当对流为亚音速时,总能发现一个动态包络结构,其时间平均径向轮廓与调整后的混合长度参数的一维模型相匹配。在三维模型中,由于不透明峰和对流效率低下,当恒星亮度局部超爱丁顿时,通常会发现超音速湍流和偶发质量损失。湍流压力在支持外包膜方面起着重要作用,这使得光球层比一维模型预测的范围更大。我们发现大质量恒星的光曲线在铁不透明峰位置的特征时间尺度上总是变化的,与热时间尺度一致。变异性的幅度和功率谱可以解释在HR图中,TESS观测到的大质量恒星在大范围参数范围内常见的随机低频变异性。三维模拟还可以解释大质量恒星的光谱拟合所需要的无处不在的宏观湍流。三维模拟对改进一维恒星演化模型的意义也进行了讨论。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
Three Dimensional Natures of Massive Star Envelopes
In this paper, we review our current understanding of the outer envelope structures of massive stars based on three-dimensional (3D) radiation hydrodynamic simulations. We briefly summarize the fundamental issues in constructing hydrostatic one-dimensional (1D) stellar evolution models when stellar luminosity approaches the Eddington value. Radiation hydrodynamic simulations in 3D covering the mass range from 13M⊙ to 80M⊙ always find a dynamic envelope structure with the time-averaged radial profiles matching 1D models with an adjusted mixing-length parameter when convection is subsonic. Supersonic turbulence and episodic mass loss are generally found in 3D models when stellar luminosity is super-Eddington locally due to the opacity peaks and convection being inefficient. Turbulent pressure plays an important role in supporting the outer envelope, which makes the photosphere more extended than predictions from 1D models. Massive star lightcurves are always found to vary with a characteristic timescale consistent with the thermal time scale at the location of the iron opacity peak. The amplitude of the variability as well as the power spectrum can explain the commonly observed stochastic low-frequency variability of mass stars observed by TESS over a wide range of parameters in an HR diagram. The 3D simulations can also explain the ubiquitous macro-turbulence that is needed for spectroscopic fitting in massive stars. Implications of 3D simulations for improving 1D stellar evolution models are also discussed.
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来源期刊
Galaxies
Galaxies Physics and Astronomy-Astronomy and Astrophysics
CiteScore
4.90
自引率
12.00%
发文量
100
审稿时长
11 weeks
期刊介绍: Es una revista internacional de acceso abierto revisada por pares que proporciona un foro avanzado para estudios relacionados con astronomía, astrofísica y cosmología. Areas temáticas Astronomía Astrofísica Cosmología Astronomía observacional: radio, infrarrojo, óptico, rayos X, neutrino, etc. Ciencia planetaria Equipos y tecnologías de astronomía. Ingeniería Aeroespacial Análisis de datos astronómicos. Astroquímica y Astrobiología. Arqueoastronomía Historia de la astronomía y cosmología. Problemas filosóficos en cosmología.
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