The weak magnetic field of the O9.7 supergiant ζ Orionis
We report here the detection of a weak magnetic field of 50–100 G on the O9.7 supergiant ζ Ori A, using spectropolarimetric observations obtained with NARVAL at the 2m Télescope Bernard Lyot atop Pic du Midi (France). ζ Ori A is the third O star known to host a magnetic field (along with θ 1 Ori C a...
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ftciteseerx:oai:CiteSeerX.psu:10.1.1.311.5964 2023-05-15T18:50:47+02:00 The weak magnetic field of the O9.7 supergiant ζ Orionis J. -c. Bouret J. -f. Donati F. Martins C. Escolano W. Marcolino T. Lanz I. D. Howarth The Pennsylvania State University CiteSeerX Archives 2008 application/pdf http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.311.5964 http://arxiv.org/pdf/0806.2162v1.pdf en eng http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.311.5964 http://arxiv.org/pdf/0806.2162v1.pdf Metadata may be used without restrictions as long as the oai identifier remains attached to it. http://arxiv.org/pdf/0806.2162v1.pdf text 2008 ftciteseerx 2016-01-07T22:33:21Z We report here the detection of a weak magnetic field of 50–100 G on the O9.7 supergiant ζ Ori A, using spectropolarimetric observations obtained with NARVAL at the 2m Télescope Bernard Lyot atop Pic du Midi (France). ζ Ori A is the third O star known to host a magnetic field (along with θ 1 Ori C and HD 191612), and the first detection on a ’normal ’ rapidly-rotating O star. The magnetic field of ζ Ori A is the weakest magnetic field ever detected on a massive star. The measured field is lower than the thermal equipartition limit (about 100 G). By fitting NLTE model atmospheres to our spectra, we determined that ζ Ori A is a 40 M ⊙ star with a radius of 25 R⊙and an age of about 5–6 Myr, showing no surface nitrogen enhancement and losing mass at a rate of about 2×10 −6 M ⊙ yr −1. The magnetic topology of ζ Ori A is apparently more complex than a dipole and involves two main magnetic polarities located on both sides of the same hemisphere; our data also suggest that ζ Ori A rotates in about 7.0 d and is about 40 ◦ away from pole-on to an Earth-based observer. Despite its weakness, the detected magnetic field Text narval narval Unknown |
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We report here the detection of a weak magnetic field of 50–100 G on the O9.7 supergiant ζ Ori A, using spectropolarimetric observations obtained with NARVAL at the 2m Télescope Bernard Lyot atop Pic du Midi (France). ζ Ori A is the third O star known to host a magnetic field (along with θ 1 Ori C and HD 191612), and the first detection on a ’normal ’ rapidly-rotating O star. The magnetic field of ζ Ori A is the weakest magnetic field ever detected on a massive star. The measured field is lower than the thermal equipartition limit (about 100 G). By fitting NLTE model atmospheres to our spectra, we determined that ζ Ori A is a 40 M ⊙ star with a radius of 25 R⊙and an age of about 5–6 Myr, showing no surface nitrogen enhancement and losing mass at a rate of about 2×10 −6 M ⊙ yr −1. The magnetic topology of ζ Ori A is apparently more complex than a dipole and involves two main magnetic polarities located on both sides of the same hemisphere; our data also suggest that ζ Ori A rotates in about 7.0 d and is about 40 ◦ away from pole-on to an Earth-based observer. Despite its weakness, the detected magnetic field |
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The Pennsylvania State University CiteSeerX Archives |
format |
Text |
author |
J. -c. Bouret J. -f. Donati F. Martins C. Escolano W. Marcolino T. Lanz I. D. Howarth |
spellingShingle |
J. -c. Bouret J. -f. Donati F. Martins C. Escolano W. Marcolino T. Lanz I. D. Howarth The weak magnetic field of the O9.7 supergiant ζ Orionis |
author_facet |
J. -c. Bouret J. -f. Donati F. Martins C. Escolano W. Marcolino T. Lanz I. D. Howarth |
author_sort |
J. -c. Bouret |
title |
The weak magnetic field of the O9.7 supergiant ζ Orionis |
title_short |
The weak magnetic field of the O9.7 supergiant ζ Orionis |
title_full |
The weak magnetic field of the O9.7 supergiant ζ Orionis |
title_fullStr |
The weak magnetic field of the O9.7 supergiant ζ Orionis |
title_full_unstemmed |
The weak magnetic field of the O9.7 supergiant ζ Orionis |
title_sort |
weak magnetic field of the o9.7 supergiant ζ orionis |
publishDate |
2008 |
url |
http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.311.5964 http://arxiv.org/pdf/0806.2162v1.pdf |
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narval narval |
genre_facet |
narval narval |
op_source |
http://arxiv.org/pdf/0806.2162v1.pdf |
op_relation |
http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.311.5964 http://arxiv.org/pdf/0806.2162v1.pdf |
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Metadata may be used without restrictions as long as the oai identifier remains attached to it. |
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