A search for magnetic fields in normal upper-main-sequence stars

Abstract

In connection with stellar fundamental structure considerations, it is of interest to investigate whether some normal upper-main-sequence stars possess fields of smaller magnitude than those found in Ap and Bp stars. Magnetic observations reported so far suggest that fields in nonpeculiar upper-main-sequence stars are not commonly much greater than approximately 500 gauss, and in a few cases are probably less than 50 gauss. In order to obtain more data, a systematic magnetic survey of a sample of upper-main-sequence stars in the range O9.5 to F6 was carried out. The magnetic observations were obtained with photoelectric Zeeman analyzers. Attention is given to the measuring techniques and reduction procedures used in the investigation, the obtained observations, and the instrumental and astrophysical conclusions which follow from the results of the survey.