• DOI:10.1051/0004-6361/201014848
• Corpus ID: 118643022

No detection of large-scale magnetic fields at the surfaces of Am and HgMn stars

@article{Aurire2010NoDO,
  title={No detection of large-scale magnetic fields at the surfaces of Am and HgMn stars},
  author={Michel Auri{\`e}re and Gregg A. Wade and François Lignières and Alain Hui-Bon-Hoa and John D. Landstreet and Ilian T. Iliev and Jean-François Donati and Pascal Petit and T. Roudier and Sylvie Th{\'e}ado},
  journal={Astronomy and Astrophysics},
  year={2010},
  volume={523}
}

• M. Aurière, G. Wade, +7 authors S. Théado
• Published 18 August 2010
• Physics
• Astronomy and Astrophysics

Aims. We investigate the magnetic dichotomy between Ap/Bp and other A-type stars by carrying out a deep spectropolarimetric study of Am and HgMn stars. Methods. Using the NARVAL spectropolarimeter at the Telescope Bernard Lyot (Observatoire du Pic du Midi, France), we obtained high-resolution circular polarisation spectroscopy of 12 Am stars and 3 HgMn stars. Results. Using least squares deconvolution (LSD), no magnetic field is detected in any of the 15 observed stars. Uncertaintiies as low as 0.3 G (respectively 1 G) have been reached for surface-averaged longitudinal magnetic field measurements for Am (respectively HgMn) stars. Conclusions. Associated with the results obtained previously for Ap/Bp stars, our study confirms the existence of a magnetic dichotomy among A-type stars. Our data demonstrate that there is at least one order of magnitude difference in field strength between Zeeman detected stars (Ap/Bp stars) and non Zeeman detected stars (Am and HgMn stars). This result confirms that the spectroscopically-defined Ap/Bp stars are the only A-type stars harbouring detectable large-scale surface magnetic fields.