Magnetic fields and the variable wind of the early-type supergiant β Ori
Thesis (Master, Physics, Engineering Physics and Astronomy) -- Queen's University, 2012-04-29 02:10:41.308 Supergiant stars of spectral types B and A are characterized by variable and structured winds, as revealed by variability of optical and ultraviolet spectral lines. Non- radial pulsations...
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ftqueensuniv:oai:https://qspace.library.queensu.ca:1974/7165 2024-06-02T08:16:03+00:00 Magnetic fields and the variable wind of the early-type supergiant β Ori Shultz, Matthew Eric Physics, Engineering Physics and Astronomy Wade, Gregg Hanes, David 2012-04-27 10:05:23.646 application/pdf http://hdl.handle.net/1974/7165 eng eng Canadian theses http://hdl.handle.net/1974/7165 This publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner. stellar winds Stars (magnetic) stars (early type) stars (supergiant) spectropolarimetry thesis 2012 ftqueensuniv 2024-05-06T10:47:32Z Thesis (Master, Physics, Engineering Physics and Astronomy) -- Queen's University, 2012-04-29 02:10:41.308 Supergiant stars of spectral types B and A are characterized by variable and structured winds, as revealed by variability of optical and ultraviolet spectral lines. Non- radial pulsations and magnetically supported loops have been proposed as explanations for these phenomena. The latter hypothesis is tested using a time series of 65 high-resolution (λ/∆λ ∼ 65, 000) circular polarization (Stokes I and V ) spectra of the late B type supergiant Rigel (β Ori, B8 Iae), obtained with the instruments ESPaDOnS and Narval at the Canada-France-Hawaii Telescope and the Bernard Lyot Telescope, respectively. Examination of the unpolarized (Stokes I) spectra using standard spectral analysis tools confirms complex line profile variability during the 5 month period of observations; the high spectral resolution allows the identification of a weak, transient Hα feature similar in behaviour to a High Velocity Absorption event. Analysis of the Stokes V spectra using the cross-correlation technique Least Squares Deconvolution (LSD) yields no evidence of a magnetic field in either LSD Stokes V profiles or longitudinal field measurements, with longitudinal field 1σ error bars of ∼ 12 G for individual observations, and a mean field in the best observed period of 3 ± 2 G. Synthetic LSD profiles fit to the observations using a Monte Carlo approach yield an upper limit on the surface dipolar field strength of Bdip ≤ 50 G for most orientations of the rotational and magnetic axes, lowered to Bdip ≤ 35 G if the mean LSD profile from the most densely time-sampled epoch (with an LSD SNR of ∼80,000) is used. A simple two-spot geometry representing the footpoints of a magnetic loop emerging from the photosphere yields upper limits on the spot magnetic fields of 60–600 G, depending on the filling factor of the spots. Given existing measurements of the mass loss rate and the wind terminal velocity, these results cannot rule out a ... Thesis narval narval Queen's University, Ontario: QSpace Canada Rigel ENVELOPE(-66.843,-66.843,-70.393,-70.393) |
institution |
Open Polar |
collection |
Queen's University, Ontario: QSpace |
op_collection_id |
ftqueensuniv |
language |
English |
topic |
stellar winds Stars (magnetic) stars (early type) stars (supergiant) spectropolarimetry |
spellingShingle |
stellar winds Stars (magnetic) stars (early type) stars (supergiant) spectropolarimetry Shultz, Matthew Eric Magnetic fields and the variable wind of the early-type supergiant β Ori |
topic_facet |
stellar winds Stars (magnetic) stars (early type) stars (supergiant) spectropolarimetry |
description |
Thesis (Master, Physics, Engineering Physics and Astronomy) -- Queen's University, 2012-04-29 02:10:41.308 Supergiant stars of spectral types B and A are characterized by variable and structured winds, as revealed by variability of optical and ultraviolet spectral lines. Non- radial pulsations and magnetically supported loops have been proposed as explanations for these phenomena. The latter hypothesis is tested using a time series of 65 high-resolution (λ/∆λ ∼ 65, 000) circular polarization (Stokes I and V ) spectra of the late B type supergiant Rigel (β Ori, B8 Iae), obtained with the instruments ESPaDOnS and Narval at the Canada-France-Hawaii Telescope and the Bernard Lyot Telescope, respectively. Examination of the unpolarized (Stokes I) spectra using standard spectral analysis tools confirms complex line profile variability during the 5 month period of observations; the high spectral resolution allows the identification of a weak, transient Hα feature similar in behaviour to a High Velocity Absorption event. Analysis of the Stokes V spectra using the cross-correlation technique Least Squares Deconvolution (LSD) yields no evidence of a magnetic field in either LSD Stokes V profiles or longitudinal field measurements, with longitudinal field 1σ error bars of ∼ 12 G for individual observations, and a mean field in the best observed period of 3 ± 2 G. Synthetic LSD profiles fit to the observations using a Monte Carlo approach yield an upper limit on the surface dipolar field strength of Bdip ≤ 50 G for most orientations of the rotational and magnetic axes, lowered to Bdip ≤ 35 G if the mean LSD profile from the most densely time-sampled epoch (with an LSD SNR of ∼80,000) is used. A simple two-spot geometry representing the footpoints of a magnetic loop emerging from the photosphere yields upper limits on the spot magnetic fields of 60–600 G, depending on the filling factor of the spots. Given existing measurements of the mass loss rate and the wind terminal velocity, these results cannot rule out a ... |
author2 |
Physics, Engineering Physics and Astronomy Wade, Gregg Hanes, David |
format |
Thesis |
author |
Shultz, Matthew Eric |
author_facet |
Shultz, Matthew Eric |
author_sort |
Shultz, Matthew Eric |
title |
Magnetic fields and the variable wind of the early-type supergiant β Ori |
title_short |
Magnetic fields and the variable wind of the early-type supergiant β Ori |
title_full |
Magnetic fields and the variable wind of the early-type supergiant β Ori |
title_fullStr |
Magnetic fields and the variable wind of the early-type supergiant β Ori |
title_full_unstemmed |
Magnetic fields and the variable wind of the early-type supergiant β Ori |
title_sort |
magnetic fields and the variable wind of the early-type supergiant β ori |
publishDate |
2012 |
url |
http://hdl.handle.net/1974/7165 |
long_lat |
ENVELOPE(-66.843,-66.843,-70.393,-70.393) |
geographic |
Canada Rigel |
geographic_facet |
Canada Rigel |
genre |
narval narval |
genre_facet |
narval narval |
op_relation |
Canadian theses http://hdl.handle.net/1974/7165 |
op_rights |
This publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner. |
_version_ |
1800740390437912576 |