A Multiwavelength Search for Intrinsic Linear Polarization in Wolf–Rayet Winds
A Multiwavelength Search for Intrinsic Linear Polarization in Wolf–Rayet Winds
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DOI：
10.3847/1538-3881/ab8293
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发表时间：
2019-12
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影响因子：
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通讯作者：
A. Fullard;N. St-Louis;A. Moffat;V. Piirola;N. Manset;J. Hoffman
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作者：
A. Fullard;N. St-Louis;A. Moffat;V. Piirola;N. Manset;J. Hoffman
沃尔夫-拉叶星有强烈的热风，其质量损失率至少是O型星的10倍，尽管它们的终端风速相似。在本文中，我们使用的技术多波段线性偏振提取信息的全球不对称的风在一个样本的47个明亮的银河系WR星。我们的观测还包括对样本中17颗恒星的随时间变化的观测。实现我们目标的途径包括去除波长相关星际偏振（ISP）的主要成分，它通常遵循众所周知的Serkowski定律。我们包括一个波长依赖的ISP位置角参数在我们的ISP法，并发现15颗星显示此参数的显着结果。我们检测到一个重要的组成部分，波长无关的偏振由于电子散射在风中的10种情况下，与大多数WR星显示没有在我们的数据的精度为0.05%的水平。内在极化的恒星可以用双星相互作用、大尺度风结构和聚集现象来解释。我们还发现，在使用Strömgren B滤波器（探测复杂的λ4600-4700发射线区域）观察到的19颗恒星中，有5颗恒星具有来自ISP定律的显著残差，并提出这是由于风的不对称性。我们提供了一个有用的目录ISP的47个明亮的银河系WR星和上限的可能水平的内在偏振。
Wolf–Rayet stars have strong, hot winds, with mass-loss rates at least a factor of 10 greater than their O-star progenitors, although their terminal wind speeds are similar. In this paper, we use the technique of multiband linear polarimetry to extract information on the global asymmetry of the wind in a sample of 47 bright Galactic WR stars. Our observations also include time-dependent observations of 17 stars in the sample. The path to our goal includes removing the dominating component of wavelength-dependent interstellar polarization (ISP), which normally follows the well-known Serkowski law. We include a wavelength-dependent ISP position angle parameter in our ISP law and find that 15 stars show significant results for this parameter. We detect a significant component of wavelength-independent polarization due to electron scattering in the wind for 10 cases, with most WR stars showing none at the ∼0.05% level precision of our data. The intrinsically polarized stars can be explained with binary interaction, large-scale wind structure, and clumping. We also found that 5 stars out of 19 observed with the Strömgren b filter (probing the complex λ4600–4700 emission-line region) have significant residuals from the ISP law and propose that this is due to wind asymmetries. We provide a useful catalog of ISP for 47 bright Galactic WR stars and upper limits on the possible level of intrinsic polarization.