Rotational modulation in B stars observed by the Kepler K2 mission

A recent analysis indicates that the number of rotational variables among B stars in the Kepler field is as high as among the A stars (about 40 per cent). We continue this investigation by studying the incidence of rotational modulation among B stars using the K2 data. These data include many early B stars which are lacking in the original Kepler field. The results indicate that rotational modulation is as common among B stars as it is among A stars. The K2 data show that 30-50 per cent of B stars (both early and late type) appear to be rotational variables, depending on which criteria are used. It appears that a large fraction of B stars have spots or other co-rotational feature, implying the possible presence of a magnetic field. Rotational modulation needs to be taken into account in any future interpretation of light and spectroscopic variations in B stars.