Colors and Variability of Magnetic Stars.

Abstract

An average of 5.4 U, B, V observations has been obtained at random times during a 2-year interval for 70 Ap magnetic stars. The mean colors agree with those of normal dwarfs and giants but for those that are about 0 2 spectral classes earlier (among the B8p-A2p stars). Mter observational inaccuracies are allowed for, it is found that all magnetic stars are slightly variable in visual light and in B - V and U - B colors. The mean dispersions from the mean are 0.039, 0.017, and 0023 mag. in V, B - V, and U - B, respectively. There is no correlation between the amounts of variability in magnitude and in color, although there is a correlation between the dispersions in the two colors. There are no correlations between the photometric dispersions and the (1) magnetic-field strengths, (2) predominant sign or regularity of the magnetic-field variations, (3) spectral peculiarities, (4) mean colors, or (S) line widths.