A Flower on a WIRE: Asteroseismology of a Massive Star

Recently it became clear from a line profile study that the β Cephei star β Crucis (Mimosa) is multiperiodic with at least three modes excited. Observations of this star by the star tracker of the WIRE satellite have now confirmed the multiperiodicity in the light variations. A total of 5 million observations covering 17 days was analysed and the three main periods are in perfect agreement with the line profile results. The amplitudes are small (3, 2.7 and 0.6 millimag for the dominant modes), but this is not surprising in view of the mode identifications derived from the line profiles. More periods could still be present, including the one earlier suggested by the radial velocity data.