Investigating the origin of cyclical wind variability in hot, massive stars - I. On the dipolar magnetic field hypothesis

the MiMeS Collaboration

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16 Scopus citations

Abstract

OB stars exhibit various types of spectral variability associated with wind structures, including the apparently ubiquitous discrete absorption components (DACs). These are proposed to be caused by either magnetic fields or non-radial pulsations. In this paper, we evaluate the possible relation between large-scale, dipolar magnetic fields and the DAC phenomenon by investigating the magnetic properties of a sample of 13 OB stars exhibiting well-documented DACbehaviour. Using high-precision spectropolarimetric data acquired in part in the context of theMagnetism inMassive Stars project, we find no evidence for surface dipolar magnetic fields in any of these stars. Using Bayesian inference, we compute upper limits on the strengths of the fields and use these limits to assess two potential mechanisms by which the field may influence wind outflow: magnetic wind confinement and local photospheric brightness enhancements. Within the limits we derive, both mechanisms fail to provide a systematic process capable of producing DACs in all of the stars of our sample. Therefore, this implies that dipolar fields are highly unlikely to be responsible for these structures in all massive stars, meaning that some other mechanism must come into play.

Original languageEnglish (US)
Pages (from-to)429-442
Number of pages14
JournalMonthly Notices of the Royal Astronomical Society
Volume444
Issue number1
DOIs
StatePublished - Jul 26 2014

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

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