标题： WR 6 星风中共转相互作用区域的偏振光变曲线建模 显示英文标题

标题： Polarization Light Curve Modeling of Corotating Interaction Regions in the Wind of the Wolf-Rayet Star WR 6

摘要： WR6这颗有趣的WN4b星几十年来一直显示出与观测时期相关的光谱、测光和偏振变化。 在本文中，我们旨在验证一个简化的解析模型，该模型假设绕转相互作用区域（CIRs）穿过原本球形的风，是否能够用一组合理的参数再现文献中的许多宽波段连续光曲线。 我们修改了Ignace、St-Louis & Proulx-Giraldeau（2015）开发的光学薄模型，以近似考虑多次散射，并用它来拟合这颗恒星的13个独立数据集。 通过在风中包含两个CIRs，我们获得了所有数据集的合理拟合，旋转轴的倾角（$i_0=166^{\circ}$）及其在天球平面内的方向具有连贯的值，尽管在后一种情况下，我们从偏振测量中得到了两个同样可接受的值（$\psi=63^{\circ}$和$\psi=152^{\circ}$）。 使用Sobolev近似进行线轮廓变化模拟，使我们能够排除$\psi=152^{\circ}$解。 采用所选配置（$i_0=166^{\circ}$和$\psi=63^{\circ}$），我们能够用两个位于恒星赤道附近且始终相隔$\sim 90^{\circ}$经度的CIRs相对较好地再现所有数据集。 历元依赖性来自于这些CIRs沿着恒星表面迁移的事实。 密度对比小于两倍且CIR（$\beta \geq 35^{\circ}$）具有较大的开口角被发现最能再现文献中报告的光谱变化类型。 显示英文摘要

摘要： The intriguing WN4b star WR6 has been known to display epoch-dependent spectroscopic, photometric and polarimetric variability for several decades. In this paper, we set out to verify if a simplified analytical model in which Corotating Interaction Regions (CIRs) threading an otherwise spherical wind is able to reproduce the many broadband continuum light curves from the literature with a reasonable set of parameters. We modified the optically thin model we developed in Ignace, St-Louis & Proulx-Giraldeau (2015) to approximately account for multiple scattering and used it to fit 13 separate datasets of this star. By including two CIRs in the wind, we obtained reasonable fits for all datasets with coherent values for the inclination of the rotation axis ($i_0=166^{\circ}$) and for its orientation in the plane of the sky, although in the latter case we obtained two equally acceptable values ($\psi=63^{\circ}$ and $\psi=152^{\circ}$) from the polarimetry. Additional line profile variation simulations using the Sobolev approximation for the line transfer allowed us to eliminate the $\psi=152^{\circ}$ solution. With the adopted configuration ($i_0=166^{\circ}$ and $\psi=63^{\circ}$), we were able to reproduce all datasets relatively well with two CIRs located near the stellar equator and always separated by $\sim 90^{\circ}$ in longitude. The epoch-dependency comes from the fact that these CIRs migrate along the surface of the star. Density contrasts smaller than a factor of two and large opening angles for the CIR ($\beta \geq 35^{\circ}$) were found to best reproduce the type of spectroscopic variability reported in the literature.