Large-scale magnetic field of the G8 dwarf ξ Bootis A

  1. P. Petit1,*,
  2. J.-F. Donati2,*,
  3. M. Aurière2,*,
  4. J. D. Landstreet3,*,
  5. F. Lignières2,*,
  6. S. Marsden4,*,
  7. D. Mouillet2,*,
  8. F. Paletou2,*,
  9. N. Toqué2,*,
  10. G. A. Wade5,*

Article first published online: 30 JUN 2005

DOI: 10.1111/j.1365-2966.2005.09207.x

Issue

Monthly Notices of the Royal Astronomical Society

Monthly Notices of the Royal Astronomical Society

Volume 361, Issue 3, pages 837–849, August 2005

Additional Information

How to Cite

Petit, P., Donati, J.-F., Aurière, M., Landstreet, J. D., Lignières, F., Marsden, S., Mouillet, D., Paletou, F., Toqué, N. and Wade, G. A. (2005), Large-scale magnetic field of the G8 dwarf ξ Bootis A. Monthly Notices of the Royal Astronomical Society, 361: 837–849. doi: 10.1111/j.1365-2966.2005.09207.x

Author Information

  1. 1

    Max-Planck Institut für Sonnensystemforschung, Max-Planck-Strasse 2, 37191 Katlenburg-Lindau, Germany

  2. 2

    Laboratoire d'Astrophysique de Toulouse-Tarbes, Observatoire Midi-Pyrénées, 14 Avenue E. Belin, F–31400 Toulouse, France

  3. 3

    Department of Physics and Astronomy, The University of Western Ontario, London, Ontario, Canada N6G 3K7

  4. 4

    Institute of Astronomy, ETH Zentrum, CH-8092 Zürich, Switzerland

  5. 5

    Royal Military College of Canada, Department of Physics, PO Box 17000, Station ‘Forces’, Kingston, Ontario, Canada, K7K 4B4

*★ E-mail: petit@linmpi.mpg.de (PP); donati@ast.obs-mip.fr (J-FD); auriere@ast.obs-mip.fr (MA); jlandstr@astro.uwo.ca (JDL); francois.lignieres@obs-mip.fr (FL); marsden@usq.edu.au (SM); mouillet@bagn.obs-mip.fr (DM); fpaletou@ast.obs-mip.fr (FP); toque@ast.obs-mip.fr (NT); Gregg.Wade@rmc.ca (GAW)

Publication History

  1. Issue published online: 8 JUL 2005
  2. Article first published online: 30 JUN 2005
  3. Accepted 2005 May 18. Received 2005 May 3; in original form 2005 March 7

SEARCH

SEARCH BY CITATION

ARTICLE TOOLS

View Full Article (HTML) Get PDF (453K)

Keywords:

  • magnetic fields;
  • stars: activity;
  • star: individual: HD 131156;
  • stars: rotation

ABSTRACT

We investigate the magnetic geometry of the active G8 dwarf ξ Bootis A (ξ Boo A), from spectropolarimetric observations obtained in 2003 with the MuSiCoS échelle spectropolarimeter at the Télescope Bernard Lyot (Observatoire du Pic du Midi, France). We repeatedly detect a photospheric magnetic field, with periodic variations consistent with rotational modulation. Circularly polarized (Stokes V) line profiles present a systematic asymmetry, showing up as an excess in amplitude and area of the blue lobe of the profiles. Direct modelling of Stokes V profiles suggests that the global magnetic field is composed of two main components, with an inclined dipole and a large-scale toroidal field. We derive a dipole intensity of about 40 G, with an inclination of 35° of the dipole with respect to the rotation axis. The toroidal field strength is of the order of 120 G. A noticeable evolution of the field geometry is observed over the 40 nights of our observation window and results in an increase in field strength and dipole inclination.

This study is the first step of a long-term monitoring of ξ Boo A and other active solar-type stars, with the aim of investigating secular fluctuations of stellar magnetic geometries induced by activity cycles.

View Full Article (HTML) Get PDF (453K)