EAS Publications Series

Magnetism and Activity of the Sun and Stars
J. Arnaud and N. Meunier (eds)
EAS Publications Series, Vol. 9, 2003
DOI: 10.1051/eas:2003120

Magnetic fields in early B-type stars

H. Henrichs¹, C. Neiner^{1, 2}, V. Geers¹ and J. de Jong³

¹ Sterrenkundig Instituut Anton Pannekoek, Universiteit van Amsterdam, Kruislaan 403, 1098 SJ, The Netherlands
² Observatoire de Meudon, France
³ Sterrewacht Leiden, The Netherlands

Abstract
We summarize results of magnetic measurements of the bright early B-type stars $\beta$ Cep, $\zeta$ Cas, and V2052 Oph, which we found to be oblique rotators with a weak magnetic dipole field with polar strength of a few hundred Gauss. From stellar wind studies we derived their rotational periods very accurately, and matched the magnetic and stellar wind phases. From model atmosphere fits we derived the angles of the rotation and magnetic axis. All three stars show some chemical abundance anomaly, likely associated with the magnetic properties. The stars are also pulsating variables. This is of high asteroseismological interest, since these are the only early-type stars known with observationally determined rotation, pulsation and magnetic properties.

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