We report the detection of phase-locked polarization in the bright ($m_V$=2.98-3.24) semidetached eclipsing binary $\mu^1$ Sco (HD 151890). The phenomenon was observed in multiple photometric bands using two different HIPPI-class (HIgh Precision Polarimetric Instrument)polarimeters with telescopes ranging in size from 35-cm to 3.9-m. The peak-to-trough amplitude of the polarization is wavelength dependent and large, $\sim$700 parts-per-million in green light, and is easily seen with even the smallest telescope. We fit the polarization phase curve with a SYNSPEC/VLIDORT polarized radiative transfer model and a Wilson-Devinney geometric formalism, which we describe in detail. Light from each star reflected by the photosphere of the other, together with a much smaller contribution from tidal distortion and eclipse effects, wholly accounts for the polarization amplitude. In the past polarization in semidetached binaries has been attributed mostly to scattering from extra-stellar gas. Our new interpretation facilitates determining masses of such stars in non-eclipsing systems.

中文翻译：

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半分离食双星μ1 Sco中光球反射的锁相偏振

我们报告了在明亮的 ($m_V$=2.98-3.24) 半分离食双星 $\mu^1$ Sco (HD 151890) 中检测到锁相偏振。使用两种不同的 HIPPI 级（高精度旋光仪）旋光仪和望远镜尺寸从 35 厘米到 3.9 米不等，在多个光度带中观察到了这种现象。偏振的峰谷幅度与波长有关且很大，在绿光中为百万分之 700 美元，即使是最小的望远镜也很容易看到。我们使用 SYNSPEC/VLIDORT 极化辐射传输模型和 Wilson-Devinney 几何形式来拟合极化相位曲线，我们对此进行了详细描述。每颗恒星发出的光被另一颗恒星的光球反射，加上潮汐畸变和日食效应的贡献小得多，完全说明极化幅度。过去，半分离双星的极化主要归因于星外气体的散射。我们的新解释有助于确定非食宿系统中此类恒星的质量。