Rapid polarization variations in the O4 supergiant ζ Puppis
Article
Bailey, Jeremy, Howarth, Ian D, Cotton, Daniel V, Kedziora-Chudczer, Lucyna, De Horta, Ain, Martell, Sarah L, Eldridge, Colin and Luckas, Paul. 2024. "Rapid polarization variations in the O4 supergiant ζ Puppis." Monthly Notices of the Royal Astronomical Society. 529 (1), pp. 374-392. https://doi.org/10.1093/mnras/stae548
Article Title | Rapid polarization variations in the O4 supergiant ζ Puppis |
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ERA Journal ID | 1074 |
Article Category | Article |
Authors | Bailey, Jeremy, Howarth, Ian D, Cotton, Daniel V, Kedziora-Chudczer, Lucyna, De Horta, Ain, Martell, Sarah L, Eldridge, Colin and Luckas, Paul |
Journal Title | Monthly Notices of the Royal Astronomical Society |
Journal Citation | 529 (1), pp. 374-392 |
Number of Pages | 19 |
Year | 2024 |
Publisher | Oxford University Press |
Place of Publication | United Kingdom |
ISSN | 0035-8711 |
1365-2966 | |
Digital Object Identifier (DOI) | https://doi.org/10.1093/mnras/stae548 |
Web Address (URL) | https://academic.oup.com/mnras/article/529/1/374/7613579 |
Abstract | We present time-series linear-polarization observations of the bright O4 supergiant ζ Puppis. The star is found to show polarization variation on time-scales of around an hour and longer. Many of the observations were obtained contemporaneously with Transiting Exoplanet Survey Satellite (TESS) photometry. We find that the polarization varies on similar time-scales to those seen in the TESS light curve. The previously reported 1.78-d photometric periodicity is seen in both the TESS and polarization data. The amplitude ratio of photometry to polarization is ∼9 for the periodic component and the polarization variation is oriented along position angle ∼70◦–160◦. Higher frequency stochastic variability is also seen in both data sets with an amplitude ratio of ∼19 and no preferred direction. We model the polarization expected for a rotating star with bright photospheric spots and find that models that fit the photometric variation produce too little polarization variation to explain the observations. We suggest that the variable polarization is more likely the result of scattering from the wind, with corotating interaction regions producing the periodic variation and a clumpy outflow producing the stochastic component. The Hα emission line strength was seen to increase by 10 per cent in 2021 with subsequent observations showing a return to the pre-2018 level. © 2024 The Author(s). |
Keywords | polarization |
Contains Sensitive Content | Does not contain sensitive content |
ANZSRC Field of Research 2020 | 5101. Astronomical sciences |
Byline Affiliations | University of New South Wales |
University College London, United Kingdom | |
Monterey Institute for Research in Astronomy, United States | |
Western Sydney University | |
Centre for Astrophysics | |
ARC Centre of Excellence for All Sky Astrophysics in 3 Dimensions, Australia | |
No affiliation | |
University of Western Australia |
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