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arXiv · 1903.06745

Variability in X-ray line ratios in helium-like ions of massive stars: the wind-driven case

R. Ignace·Z. Damrau·K. T. Hole
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Abstract

High spectral resolution and long exposure times are providing unprecedented levels of data quality of massive stars at X-ray wavelengths. A key diagnostic of the X-ray emitting plasma are the fir lines for He-like triplets. In particular, owing to radiative pumping effects, the forbidden-to-intercombination line luminosity ratio, R=f/i, can be used to determine the proximity of the hot plasma to the UV-bright photospheres of massive stars. Moreover, the era of large observing programs additionally allows for investigation of line variability. This contribution is the second to explore how variability in the line ratio can provide new diagnostic information about distributed X-rays in a massive star wind. While there are many ways to drive variability in the line ratio, we use variable mass loss as an illustrative example. The f/i ratio can be significantly modulated owing to evolving wind properties. We evaluate how variable mass loss might bias measures of f/i.

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R. Ignace, Z. Damrau, K. T. Hole. 2019-03-15. Variability in X-ray line ratios in helium-like ions of massive stars: the wind-driven case. https://doi.org/10.1051/0004-6361%2F201834752e

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