Astron. Astrophys. 363, 585-592 (2000)

Modeling line profile variations of  Ori E and  Ori C

A. Reiners ¹, O. Stahl ¹, B. Wolf ¹, A. Kaufer ² and T. Rivinius <sup>*  2

1</sup> Landessternwarte Heidelberg, Königstuhl, 69117 Heidelberg, Germany (A.Reiners@lsw.uni-heidelberg.de)
² European Southern Observatory, Karl-Schwarzschild-Strasse 2, 85748 Garching bei München, Germany

Received 20 March 2000 / Accepted 8 September 2000

Abstract

We analyse phase-dependent variations of the photospheric lines of the magnetic B star  Ori E and the suspected magnetic O star  Ori C. In the framework of the oblique magnetic rotator model, the observations are interpreted as the result of inhomogeneous chemical abundances - spots - at the stellar surface. This model can at least qualitatively explain the line profile variations with two spots at the magnetic poles of both stars. In the case of  Ori E, we find the spots to be overabundant in He and depleted in metals. For  Ori C the presumed spots would be depleted both in He and in metals. For  Ori C we also discuss an alternative model with spots of enhanced abundances at the magnetic equator. This model better fits the observations. Chemical fractionation is not expected for  Ori C and the absorption lines show indications of circumstellar absorption. Therefore, the most likely interpretation of the variations observed in the absorption lines of this star is the presence of excess absorption in a circumstellar cloud and not that of a difference in chemical abundance.

Key words: stars: chemically peculiar stars: early-type stars: individual: oe Ori E stars: individual: 1  Ori C stars: magnetic fields stars: statistics

* Based on observations collected at the European Southern Observatory, La Silla, Chile

Send offprint requests to: A. Reiners

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Contents

• 1. Introduction
• 2. Observations and data reduction
• 3. Synthetic spectra and line profile variations
• 4.  Ori E
• 5.  Ori C
  • 5.1. A polar spot model for  Ori C
  • 5.2. An equatorial spot model for  Ori C
• 6. Discussion
• Acknowledgements
• References

© European Southern Observatory (ESO) 2000

Online publication: December 11, 2000
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