Lifting the veil on Wolf-Rayet rotation using wind structure: Multi-wavelength and Spectropolarimetric Approaches

当Wolf-Rayet(WR)恒星变成超新星时，它的核心会坍塌，形成黑洞或中子星。结果取决于WR恒星的自转速度，但对于WR恒星来说，这很难测量，因为它们被自己的风所笼罩。然而，风中的扭曲可以形成共旋相互作用区(CIR)，它充当时钟，使旋转周期得以确定。伊格内斯和他的团队将监测WR恒星以寻找CIR。他们将确定旋转周期，并使用他们的理论模型进一步解释这些观测结果，以帮助我们理解风特征是如何形成的。本科生将被招募参加暑期研究项目。伊格内斯和他的团队将为普通公众和当地高中开发一个天文馆表演。关于“太空天气”的节目将包括一个关于太阳风中的CIR如何增强地磁风暴的片段。该团队将增强现有的蒙特卡罗辐射传输程序，以表征旋转效应如何调制风并形成CIRS。将这些模型与加拿大法夏威夷望远镜上用于观测恒星的Echelle光谱偏振装置的观测结果进行比较，将得出WR风中复杂结构的强劲图像。该团队将首次能够将厚风中的电子散射极化与轴对称WR风的模型联系起来，作为相对于临界分裂的恒星旋转的函数。对极化的变化和不变的贡献进行建模对于测量周期和限制质量损失率都很重要。为了完成这幅图，该团队将模拟CIRS对可变的IR/无线电连续谱通量的影响。偏振探测内风中的结构；长波长连续统探测渐近流。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

When a Wolf-Rayet (WR) star goes supernova, its core collapses to form either a black hole or a neutron star. The outcome depends on how fast the WR star was spinning, but this is difficult to measure for WR stars, which are shrouded by their own wind. However, distortions in the wind can form corotating interaction regions (CIRs), which act as clocks and enable the spin period to be determined. Ignace and his team will monitor WR stars to look for CIRs. They will determine the spin period and further interpret these observations using their theoretical models to help us understand how wind features are formed. Undergraduate students will be recruited for a summer research program. Ignace and his team will develop a planetarium show for the general public and local high schools. The show on “space weather” will include a segment on how CIR’s in the Solar wind can enhance geomagnetic storms. The team will enhance an existing Monte Carlo radiative transfer code to characterize how rotational effects can modulate the wind and form CIRs. The comparison of the models to observations with the Echelle SpectroPolarimetric Device for the Observation of Stars on the Canada France Hawaii Telescope will result in a robust picture of the complex structures in WR winds. For the first time, the team will be able to relate electron scattering polarization in thick winds with a model for axisymmetric WR winds, as a function of stellar rotation relative to critical break-up. Modeling both varying and non-varying contributions to polarization is important for measuring periods and constraining mass-loss rates. To complete the picture, the team will model the influence of CIRs on variable IR/radio continuum flux. Polarization probes structures in the inner wind; the long-wavelength continuum probes the asymptotic flow.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.