SIMBAD references

The light variability of six helium-weak stars is studied in the uvby system. Here we present more refined values of the period for the stars HD 49333 (2.179232±0.000009d), HD 125823 (8.817744±0.00011d), and HD 142990 (0.979070±0.000011d). The periods of HD 144334 (1.494971d) and HD 175362 (3.67375d) are confirmed. The light variability of HD 74196 is not confirmed, indeed this star is found to be constant within 0.01mag. For those stars with enough available data, we find a well defined antiphase relation between light and HeIλ4026 line equivalent width variations: however, on the basis of atmosphere model calculations, we can exclude that light variations could be mainly due to the different helium abundance concentrations on the stellar surface. The possibility of a lower temperature at the magnetic poles is considered and the evidence for a small mass loss rate from the magnetic pole regions is discussed.