Proceedings of the 4th HELAS International Conference: Seismological Challenges for Stellar Structure
4th HELAS International Conference: Seismological Challenges for Stellar Structure
1-5 février 2010
Instituto de Astrofísica de Canarias
[en] Astrophysics - Solar and Stellar Astrophysics
[en] Slowly Pulsating B and ß Cephei are ĸ mechanism driven pulsating B stars. That ĸ mechanism works since a peak in the opacity due to a high number of atomic transitions from iron-group elements occurs in the area of log T ~ 5.3. Theoretical results predict very few SPBs and no ß Cep to be encountered in low metallicity environments such as the Small Magellanic Cloud. However recent variability surveys of B stars in the SMC reported the detection of a significant number of SPB and ß Cep candidates. Though the iron content plays a major role in the excitation of ß Cep and SPB pulsations, the chemical mixture representative of the SMC B stars such as recently derived does not leave room for a significant increase of the iron abundance in these stars. Whilst abundance of iron-group elements seems reliable, is the opacity in the iron-group elements bump underestimated? We determine how the opacity profile in B-type stars should change to excite SPB and ß Cep pulsations in early-type stars of the SMC.