Astron. Astrophys. 355, 1080-1086 (2000)

Magnetic field geometries of two slowly rotating Ap/Bp stars: HD 12288 and HD 14437

G.A. Wade ¹, D. Kudryavtsev ², I.I. Romanyuk ², J.D. Landstreet ³ and G. Mathys <sup>4

1</sup> Astronomy Department, The University of Toronto at Mississauga, Mississauga, Ontario, Canada L5L 1C6
² Special Astrophysical Observatory, Russian Academy of Sciences, 357 147 Niznij Arkhyz, Russia
³ Physics & Astronomy Department, University of Western Ontario, London, Ontario, Canada N6A 3K7
⁴ European Southern Observatory, Casilla 19001, Santiago 19, Chile

Received 20 December 1999 / Accepted 20 January 2000

Abstract

In this paper we report magnetic field models and basic physical parameters for the slowly rotating Ap/Bp stars HD 12288 and HD 14437.

Using new and previously published mean longitudinal magnetic field, mean magnetic field modulus, and HIPPARCOS photometric measurements, we have inferred the rotational periods of both stars (HD 12288: ; HD 14437: ). From the magnetic measurements we have determined the best-fit decentred magnetic dipole configurations. For HD 12288, we find that the field geometry is consistent with a centred dipole, while for HD 14437 a large decentring parameter is inferred. Both stars show one angle in the ambiguous couplet which is smaller than about . This is consistent with the observation of Landstreet & Mathys (2000), who point out that almost all magnetic Ap stars with periods longer than about 30 days exhibit magnetic fields aligned with their rotational axis.

Key words: polarization stars: chemically peculiar stars: evolution stars: individual: HD 12288 stars: individual: HD 14437 stars: magnetic fields

Send offprint requests to: G.A. Wade

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Contents

• 1. Introduction
• 2. Observations
  • 2.1. Longitudinal magnetic field measurements
    • 2.1.1. SAO measurements
    • 2.1.2. UWO measurements
  • 2.2. Mean magnetic field modulus measurements
  • 2.3. HIPPARCOS photometry
• 3. Rotational periods
  • 3.1. HD 12288
  • 3.2. HD 14437
• 4. Magnetic field geometries
• 5. Basic physical parameters
• 6. Discussion and conclusions
• Acknowledgements
• References

© European Southern Observatory (ESO) 2000

Online publication: March 21, 2000
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