Spectrum variability of some selected bright CP stars on the main sequence

Abstract

The initial findings of a survey for spectrum variations in selected CP stars is reported. It is found that almost all observed mercury-manganese stars are spectrum variables. The implications of chemical anomalies in these stars are briefly discussed. In particular, arguments are advanced against the general assumption that CP3 stars are nonmagnetic. The observed low rotational velocities of the CP3 stars are interpreted as rotational braking by magnetic fields mostly in the pre-main-sequence stage of evolution of these objects. The hypothesis is advanced that high resolution spectroscopic observations of such stars would exhibit Zeeman-broadening in lines that vary in strength and are also sensitive to the magnetic field.