HD 42927 and HD 126341: two pulsating B stars surrounded by circumstellar dust

We have performed an infrared study of pulsating B stars. The main conclusi on is that none of the 163 (non-)radial pulsators shows an LR excess flux d ue to free-free emission, despite the fact that the sample contains several rapid rotators. Two beta Cep stars and two slowly pulsating B stars do exh ibit an unexpected infrared colour excess at 12 mu m. The small IR excess of the B2IV beta Cep star HD 126341 (tau(1) Lup) is not accompanied by H alpha emission nor by a near-IR excess. It follows an ene rgy distribution described by a power-law that points to dust emission. An optically thin dust model is fitted to the IR data and leads to the presenc e of circumstellar dust which is situated very far from the star. The infrared data of the star HD 42927 also point towards the presence of(h otter) dust which is situated close to the star We have gathered follow-up photometry and high-resolution spectroscopy that confirm the Hipparcos clas sification of the star as a new slowly pulsating B star. We briefly discuss the connection between these two pulsating stars and the occurrence of circumstellar dust around main-sequence stars.