An Observational Evaluation of Magnetic Confinement in the Winds of BA Supergiants
Magnetic wind confinement has been proposed as one explanation for the complex wind structures of supergiant stars of spectral types B and A. Observational investigation of this hypothesis was undertaken using high-resolution (λ/Δλ {\sim} 65,000) circular polarization (Stokes V ) spectra of six late...
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ftdatacite:10.48550/arxiv.1311.5116 2023-05-15T18:50:48+02:00 An Observational Evaluation of Magnetic Confinement in the Winds of BA Supergiants Shultz, M. Wade, G. A. Petit, V. Grunhut, J. Neiner, C. Hanes, D. Collaboration, the MiMeS 2013 https://dx.doi.org/10.48550/arxiv.1311.5116 https://arxiv.org/abs/1311.5116 unknown arXiv https://dx.doi.org/10.1093/mnras/stt2260 arXiv.org perpetual, non-exclusive license http://arxiv.org/licenses/nonexclusive-distrib/1.0/ Solar and Stellar Astrophysics astro-ph.SR FOS Physical sciences article-journal Article ScholarlyArticle Text 2013 ftdatacite https://doi.org/10.48550/arxiv.1311.5116 https://doi.org/10.1093/mnras/stt2260 2022-04-01T13:12:47Z Magnetic wind confinement has been proposed as one explanation for the complex wind structures of supergiant stars of spectral types B and A. Observational investigation of this hypothesis was undertaken using high-resolution (λ/Δλ {\sim} 65,000) circular polarization (Stokes V ) spectra of six late B and early A type supergiants (β Ori, B8Iae; 4 Lac, B9Iab; η Leo, A0Ib; HR1040, A0Ib; α Cyg, A2Iae; ν Cep, A2Iab), obtained with the instruments ESPaDOnS and Narval at the Canada-France-Hawaii Telescope and the Bernard Lyot Telescope. Least Squares Deconvolution (LSD) analysis of the Stokes V spectra of all stars yields no evidence of a magnetic field, with best longitudinal field 1σ error bars ranging from {\sim}0.5 to {\sim}4.5 G for most stars. Spectrum synthesis analysis of the LSD profiles using Bayesian inference yields an upper limit with 95.4% credibility on the polar strength of the (undetected) surface dipole fields of individual stars ranging from 3 to 30 G. These results strongly suggest that magnetic wind confinement due to organized dipolar magnetic fields is not the origin of the wind variability of BA supergiant stars. Upper limits for magnetic spots may also be inconsistent with magnetic wind confinement in the limit of large spot size and filling factor, depending on the adopted wind parameters. Therefore, if magnetic spots are responsible for the wind variability of BA supergiant stars, they likely occupy a small fraction of the photosphere. : 14 pages, 7 figures Text narval narval DataCite Metadata Store (German National Library of Science and Technology) Canada |
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Solar and Stellar Astrophysics astro-ph.SR FOS Physical sciences |
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Solar and Stellar Astrophysics astro-ph.SR FOS Physical sciences Shultz, M. Wade, G. A. Petit, V. Grunhut, J. Neiner, C. Hanes, D. Collaboration, the MiMeS An Observational Evaluation of Magnetic Confinement in the Winds of BA Supergiants |
topic_facet |
Solar and Stellar Astrophysics astro-ph.SR FOS Physical sciences |
description |
Magnetic wind confinement has been proposed as one explanation for the complex wind structures of supergiant stars of spectral types B and A. Observational investigation of this hypothesis was undertaken using high-resolution (λ/Δλ {\sim} 65,000) circular polarization (Stokes V ) spectra of six late B and early A type supergiants (β Ori, B8Iae; 4 Lac, B9Iab; η Leo, A0Ib; HR1040, A0Ib; α Cyg, A2Iae; ν Cep, A2Iab), obtained with the instruments ESPaDOnS and Narval at the Canada-France-Hawaii Telescope and the Bernard Lyot Telescope. Least Squares Deconvolution (LSD) analysis of the Stokes V spectra of all stars yields no evidence of a magnetic field, with best longitudinal field 1σ error bars ranging from {\sim}0.5 to {\sim}4.5 G for most stars. Spectrum synthesis analysis of the LSD profiles using Bayesian inference yields an upper limit with 95.4% credibility on the polar strength of the (undetected) surface dipole fields of individual stars ranging from 3 to 30 G. These results strongly suggest that magnetic wind confinement due to organized dipolar magnetic fields is not the origin of the wind variability of BA supergiant stars. Upper limits for magnetic spots may also be inconsistent with magnetic wind confinement in the limit of large spot size and filling factor, depending on the adopted wind parameters. Therefore, if magnetic spots are responsible for the wind variability of BA supergiant stars, they likely occupy a small fraction of the photosphere. : 14 pages, 7 figures |
format |
Text |
author |
Shultz, M. Wade, G. A. Petit, V. Grunhut, J. Neiner, C. Hanes, D. Collaboration, the MiMeS |
author_facet |
Shultz, M. Wade, G. A. Petit, V. Grunhut, J. Neiner, C. Hanes, D. Collaboration, the MiMeS |
author_sort |
Shultz, M. |
title |
An Observational Evaluation of Magnetic Confinement in the Winds of BA Supergiants |
title_short |
An Observational Evaluation of Magnetic Confinement in the Winds of BA Supergiants |
title_full |
An Observational Evaluation of Magnetic Confinement in the Winds of BA Supergiants |
title_fullStr |
An Observational Evaluation of Magnetic Confinement in the Winds of BA Supergiants |
title_full_unstemmed |
An Observational Evaluation of Magnetic Confinement in the Winds of BA Supergiants |
title_sort |
observational evaluation of magnetic confinement in the winds of ba supergiants |
publisher |
arXiv |
publishDate |
2013 |
url |
https://dx.doi.org/10.48550/arxiv.1311.5116 https://arxiv.org/abs/1311.5116 |
geographic |
Canada |
geographic_facet |
Canada |
genre |
narval narval |
genre_facet |
narval narval |
op_relation |
https://dx.doi.org/10.1093/mnras/stt2260 |
op_rights |
arXiv.org perpetual, non-exclusive license http://arxiv.org/licenses/nonexclusive-distrib/1.0/ |
op_doi |
https://doi.org/10.48550/arxiv.1311.5116 https://doi.org/10.1093/mnras/stt2260 |
_version_ |
1766244551773650944 |