3D hydrodynamical simulations of corotating interaction regions in rotating line-driven stellar winds
3D hydrodynamical simulations of corotating interaction regions in rotating line-driven stellar winds
复制标题
旋转线驱动恒星风中同转相互作用区域的 3D 流体动力学模拟
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发表时间：
2004
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影响因子：
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通讯作者：
L. Dessart
中科院分区：
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作者：
L. Dessart
我提出了辐射流体动力学模拟旋转线驱动的O-星风的表面变化采取的局部明亮的高斯斑点的形状。在Cranmer和Owocki的工作基础上，研究了1）将模拟域从2D（赤道面）扩展到3D（球面的八分点）和2）明确考虑辐射加速度的横向分量对共转相互作用区域（CIR）的影响，这些辐射加速度是使用可见恒星盘在所有风位置的多射线求积计算的。我确定的风旋转下来的Gayley和Owocki，目前在未受干扰的旋转热星星风的效果。在2D模拟中，辐射加速度的扰动方位分量不改变CIR的总体性质。然而，由此产生的扰动方位角速度极值增强了50倍相比，未扰动的模型，使其幅度是现在的几倍大于所采用的等温声速。与Cranmer & Owocki相比，风材料在点的垂直方向上的这种横向加宽导致CIR压缩的整体减弱。在3D中，与等效的2D模拟相比，额外的维度进一步削弱了CIR压缩和相关的速度扭结。3D模拟证实了Cranmer和Owocki的假设，即表面斑点影响的角度范围在方位角和纬度方向上是相似的。非赤道点的3D模拟揭示了CIR沿沿着固定纬度平流输出的存在，即以点纬度为中心并包含在圆锥壳内，圆锥壳的纬度厚度为高斯点的半峰全宽的数量级。因此，CIR性质基本上与基底扰动的纬度无关。这些结果表明，线驱动风的关键属性受到基础亮度的变化，很好地描述了只考虑径向辐射加速度的扰动，与高斯斑点，角调制只依赖于距离斑点的位置，无论纬度或方位角方向。根据Cranmer和Owocki的技术，我已经进行了光谱线合成计算的基础上获得的2D流体动力学输入使用多射线计算的多分量扰动辐射加速度或其扰动径向分量。对于P-Cygni和发射线轮廓，流体动力学输入的差异对轮廓形状的影响并不明显。因此，在克兰默和Owocki开发的方法是足够的大幅度长期线轮廓的变化，在许多O-星光谱的广泛调查。
I present radiation hydrodynamics simulations of rotating line-driven O-star winds subject to surface variations tak- ing the shape of localized bright Gaussian spots. Following the original work of Cranmer & Owocki, I investigate the influence on resulting corotating interaction regions (CIRs) of 1) extending the simulation domain from 2D (equatorial plane) to 3D (oc- tant of a sphere) and 2) explicitly account for the lateral components of the radiative acceleration, computed using a multiple-ray quadrature of the visible stellar disk at all wind locations. I identify the wind spin down effect of Gayley & Owocki, present in unperturbed rotating hot star winds. In 2D simulations, the perturbed azimuthal component of the radiative acceleration does not change the gross properties of CIRs. However, the resulting perturbed azimuthal velocity extrema are enhanced by a factor of 50 compared to unperturbed models, so that its magnitude is now a few times greater than the adopted isothermal sound speed. This lateral broadening of wind material at the vertical of a spot leads to an overall weakening of the CIR compression compared to Cranmer & Owocki. In 3D, the extra dimension weakens further the CIR compression and associated velocity kink compared to equivalent 2D simulations. 3D simulations confirm the assumption of Cranmer & Owocki that the angular extent of a surface spot influence is similar in the azimuthal and latitudinal directions. 3D simulations for off-equatorial spots reveal the presence of CIRs advecting out along a fixed latitude, i.e. centred on the spot latitude and contained within a conic shell whose latitudinal thickness is of the order of the full-width-half-maximum of the Gaussian spot. Thus, the CIR properties are essentially independent of the latitude of base perturbations. These results suggest that the key properties of a line-driven wind subject to base brightness variations are well described by considering only the perturbation on the radial radiative ac- celeration, with, for a Gaussian spot, an angular modulation solely dependent on the distance to the spot location, irrespective of the latitudinal or azimuthal direction. Following the technique of Cranmer & Owocki, I have performed spectroscopic line synthesis computations based on 2D hydrodynamical inputs obtained using the multi-ray computation of the multi-component perturbed radiative acceleration or its perturbed radial component. For both P-Cygni and emission line profiles, the differences in hydrodynamical inputs have unnoticeable effects on profile shapes. The method developed in Cranmer & Owocki is therefore adequate for extensive investigations of the large-amplitude long-term line profile variability identified in many O-star spectra.