Understanding the evolution of massive binary stars requires accurate estimates of their masses. This understanding is critically important because massive star evolution can potentially lead to gravitational wave sources such as binary black holes or neutron stars. For Wolf-Rayet stars with optically thick stellar winds, their masses can only be determined with accurate inclination angle estimates from binary systems which have spectroscopic $M \sin i$ measurements. Orbitally-phased polarization signals can encode the inclination angle of binary systems, where the Wolf-Rayet winds act as scattering regions.
We investigated four Wolf-Rayet + O star binary systems, WR 42, WR 79, WR 127, and WR 153, with publicly available phased polarization data to estimate their masses. To avoid the biases present in analytic models of polarization while retaining computational expediency, we used a Monte Carlo radiative transfer model accurately emulated by a neural network. We used the emulated model to investigate the posterior distribution of parameters of our four systems. Our mass estimates calculated from the estimated inclination angles put strong constraints on existing mass estimates for three of the systems, and disagrees with the existing mass estimates for WR 153. We recommend a concerted effort to obtain polarization observations that can be used to estimate the masses of Wolf-Rayet binary systems and increase our understanding of their evolutionary paths.
The inner dust shell of Betelgeuse detected by polarimetric aperture-masking interferometry
围绕着充满尘埃的恒星风起源于演化的恒星的理论仍然陷入争议之中。在表面上方大约第一个恒星半径范围内描述形成轨迹和尘埃分布对于理解质量损失现象背后的物理学至关重要。利用干涉偏振测量，我们得到的基本参数，支配尘埃结构的风基地的红超巨星。我们提出了近红外孔径掩蔽观测参宿四偏振模式获得的NACO/SAMPol仪器。我们使用参数模型和辐射转移模拟来预测偏振差分能见度数据，并将其与SPHERE/ZIMPOL测量结果进行比较。使用薄的尘埃壳模型，我们报告的尘埃晕，位于只有0.5 R $_{\star}$以上的光球（即1.5 R $_{\star}$的尘埃晕的内半径）的发现。在米氏散射假设下，通过拟合数据，我们估计了各种尘埃的粒度和密度。通过使用辐射转移模拟外推到可见光波长，我们将我们的模型与SPHERE/ZIMPOL数据进行比较，发现基于以镁橄榄石为主的尘埃混合物的模型最受欢迎。如此紧密的尘埃大气层对红超巨星周围的尘埃形成机制有着深远的影响。
An empirical view of the extended atmosphere and inner envelope of the asymptotic giant branch star R Doradus. II. Constraining the dust properties with radiative transfer modelling
Chalmers University of Technology（查尔姆斯理工大学）；Gothenburg University（哥德堡大学）
A survey of the linear polarization of directly imaged exoplanets and brown dwarf companions with SPHERE-IRDIS. First polarimetric detections revealing disks around DH Tau B and GSC 6214-210 B
年轻的巨行星和褐矮星同伴发出近红外辐射，可以线性偏振高达百分之几。这种偏振现象可以揭示出星下吸积盘的存在，旋转引起的大气扁率，或者大气尘埃云的不均匀分布。我们测量了近红外线偏振的20个已知的直接成像的系外行星和褐矮星同伴与高对比度成像仪SPHERE-IRDIS在VLT。我们使用IRDAP管道减少了数据，以校正仪器偏振和串扰，偏振度的绝对偏振精度<0.1%。我们报告了第一次探测到来自亚恒星同伴的偏振，DH Tau B和GSC 6214-210 B在H波段的偏振为百分之零点几。通过将测量到的偏振与邻近恒星的偏振进行比较，我们发现这种偏振不太可能是由星际尘埃引起的。因为同伴们先前已经测量过氢的发射谱线和红色，所以偏振极有可能来自环亚恒星盘。通过辐射转移模型，我们约束的磁盘的位置角度，并发现磁盘必须有很大的倾角。这些盘的存在以及DH Tau B的盘与其主星周围的盘的错位表明伴星是在原地形成的。对于其他18个同伴，我们没有检测到显着的极化和地方subpercent上限的极化程度。这些未被探测到的现象可能表明没有环亚恒星盘，年轻伴星的旋转速度很慢，上层大气主要含有亚微米大小的尘埃颗粒，和/或有限的云不均匀性。最后，我们给出了DH Tau，GQ Lup，PDS 70，Beta Pic和HD 106906的拱星盘的图像。
