# Can an underestimation of opacity explain B-type pulsators in the SMC - Astrophysics > Solar and Stellar Astrophysics

Abstract: Slowly Pulsating B and $\beta$ Cephei are $\kappa$ mechanism driven pulsatingB stars. That $\kappa$ mechanism works since a peak in the opacity due to ahigh number of atomic transitions from iron-group elements occurs in the areaof $\log T \approx 5.3$. Theoretical results predict very few SPBs and no$\beta$ Cep to be encountered in low metallicity environments such as the SmallMagellanic Cloud. However recent variability surveys of B stars in the SMCreported the detection of a significant number of SPB and $\beta$ Cepcandidates. Though the iron content plays a major role in the excitation of$\beta$ Cep and SPB pulsations, the chemical mixture representative of the SMCB stars such as recently derived does not leave room for a significant increaseof the iron abundance in these stars. Whilst abundance of iron-group elementsseems reliable, is the opacity in the iron-group elements bump underestimated?We determine how the opacity profile in B-type stars should change to exciteSPB and $\beta$ Cep pulsations in early-type stars of the SMC.

Author: S. Salmon, J. Montalbán, A. Miglio, M-A. Dupret, T. Morel, A. Noels

Source: https://arxiv.org/