Abstract

This paper reports a null magnetic field measurement for the O4ef star Zeta Pup, with sigma approximately equal to 100 gauss. The observations do not eliminate a corotating magnetic wind model for the star because a surface field of over 2 kilogauss could escape detection. However, theoretical arguments do not support the suggestion that Type III P Cygni profiles may result from corotation of the stellar wind. If an expanding envelope is forced into solid body rotation by a global magnetic field, the resultant line profiles are expected to be of Type VI (Be-like) and not Type III.