Abstract
To date, only a small number of O and early B-type stars have been investigated for magnetic fields, and as a result, only about a dozen magnetic early B-type stars and only few magnetic O stars are known. The lack of information on the existence, origin and role of magnetic fields in massive stars is especially disturbing because magnetic fields may have paramount influence on the stellar evolution of high-mass stars. Our study focuses on the magnetic fields in early B-type stars with a stronger emphasis on β Cep and SPB stars. Weak longitudinal magnetic fields (up to ∼ 300 G) have been recently detected using FORS 1 in a few β Cep and SPB stars, proving that these types of massive B-type stars can no longer be considered as non-magnetic.