Do A-type Supergiants have Magnetic Fields?

摘要

The accepted driving mechanism for the mass loss in A-supergiants is radiation pressure. Several clues, however, point to a model of co-rotating clouds of gas and the existence of a weak magnetic field on the surface. We report on spectropolarimetric observations between 1999 and 2003 of 12 A-type supergiants taken with the MuSiCoS spectropolarimeter at the 2m Bernard Lyot telescope at the Pic-du-Midi. We present the values of the derived longitudinal component of the magnetic field. The significance of the results is discussed.