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arXiv 0909.4383astro-ph.SR
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大质量O+O星双星中辐射驱动碰撞风的三维模型- III。热X射线发射

3D models of radiatively driven colliding winds in massive O+O star binaries - III. Thermal X-ray emission

J. M. Pittard, E. R. Parkin

摘要:

研究了短周期大质量O+ O星双星中风-风碰撞产生的X射线辐射。排放量计算从三维流体动力学模型,其中包括重力,驱动的风,恒星的轨道运动,和辐射冷却的冲击等离子体。恒星掩星和星周衰减量的变化在圆轨道系统中引入了与相位相关的X射线变化,而在偏心轨道系统中也会发生本征发射的强烈变化。在偏心系统中的X射线发射可以显示出强烈的滞后现象,在近星点之后的发射比在近星点之前的相应轨道相位处的发射更柔和,反映了在这些时间处的冲击等离子体的物理状态。此外,亮度上升到最大值并不一定遵循1/D定律。我们的模型进一步表明,有效的拱柱可以高度依赖于能量。我们模拟钱德拉和朱雀观测,并适合这些使用标准XSPEC模型。我们发现,恢复温度从两个或三个温度mekal适合那些从适合到真正的系统具有类似的恒星和轨道参数/性质的排放。我们还发现,当全球丰度在光谱拟合中解冻时,尽管计算使用太阳值作为输入(删节),但只返回太阳下值。

英文摘要:

The X-ray emission from the wind-wind collision in short-period massive O+O-star binaries is investigated. The emission is calculated from three-dimensional hydrodynamical models which incorporate gravity, the driving of the winds, orbital motion of the stars, and radiative cooling of the shocked plasma. Changes in the amount of stellar occultation and circumstellar attenuation introduce phase-dependent X-ray variability in systems with circular orbits, while strong variations in the intrinsic emission also occur in systems with eccentric orbits. The X-ray emission in eccentric systems can display strong hysteresis, with the emission softer after periastron than at corresponding orbital phases prior to periastron, reflecting the physical state of the shocked plasma at these times. Furthermore, the rise of the luminosity to maximum does not necessarily follow a 1/D law. Our models further demonstrate that the effective circumstellar column can be highly energy dependent. We simulate Chandra and Suzaku observations, and fit these using standard XSPEC models. We find that the recovered temperatures from two or three-temperature mekal fits are comparable to those from fits to the emission from real systems with similar stellar and orbital parameters/nature. We also find that when the global abundance is thawed in the spectral fits, sub-solar values are exclusively returned, despite the calculations using solar values as input (abridged).

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