Estrellas B con líneas en emisión: Enigmas y dilemas

Throughout this review I will describe the current state and open issues of some B emission line star groups, particularly the Be and B[e] stars. What are the properties of these stars? Do they rotate at the critical speed? What characteristics do their circumstellar gaseous and dusty discs show? Do we know how these discs are formed and evolve? To deal with the complex phenomena that characterize these stars, our research group addressed them using multiple observation techniques with high spatial, spectral and temporal resolution. Furthermore, to interpret the formation and dissipation of circumstellar discs, we used non-rotating and rotating stellar wind models, where the radiation pressure and rotation play an important role in the mass-loss process.