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arXiv · 1702.08535

New Insights into the Puzzling P-Cygni Profiles of Magnetic Massive Stars

Christiana Erba·Alexandre David-Uraz·Veronique Petit·Stanley P. Owocki
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Abstract

Magnetic massive stars comprise approximately 10% of the total OB star population. Modern spectropolarimetry shows these stars host strong, stable, large-scale, often nearly dipolar surface magnetic fields of 1 kG or more. These global magnetic fields trap and deflect outflowing stellar wind material, forming an anisotropic magnetosphere that can be probed with wind-sensitive UV resonance lines. Recent HST UV spectra of NGC 1624-2, the most magnetic O star observed to date, show atypically unsaturated P-Cygni profiles in the Civ resonant doublet, as well as a distinct variation with rotational phase. We examine the effect of non-radial, magnetically-channeled wind outflow on P-Cygni line formation, using a Sobolev Exact Integration (SEI) approach for direct comparison with HST UV spectra of NGC 1624-2. We demonstrate that the addition of a magnetic field desaturates the absorption trough of the P-Cygni profiles, but further efforts are needed to fully account for the observed line profile variation. Our study thus provides a first step toward a broader understanding of how strong magnetic fields affect mass loss diagnostics from UV lines.

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Christiana Erba, Alexandre David-Uraz, Veronique Petit, Stanley P. Owocki. 2017-02-27. New Insights into the Puzzling P-Cygni Profiles of Magnetic Massive Stars. https://doi.org/10.1017/s174392131700309x

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