Rotational modulation in TESS B stars 1 Rotational modulation in TESS B stars

Light curves and periodograms of 160 B stars observed by the TESS space mission and 29 mainsequence B stars from Kepler and K2 were used to classify the variability type. There are 114 mainsequence B stars in the TESS sample, of which 45 are classified as possible rotational variables. This confirms previous findings that a large fraction (about 40 percent) of A and B stars may exhibit rotational modulation. Gaia DR2 parallaxes were used to estimate luminosities, from which the radii and equatorial rotational velocities can be deduced. It is shown that observed values of the projected rotational velocities are lower than the estimated equatorial velocities for nearly all the stars, as they should be if rotation is the cause of the light variation. We conclude that a large fraction of mainsequence B stars appear to contain surface features which cannot likely be attributed to abundance patches.