Abstract
ABSTRACT Intensity and wavelength variations have been determined for the lines H 8 and H7, the Mg ii line at 4481 A, and the K line of Ca ii. The equivalent widths of all of these features vary with a period of 0d728 in synchronism with the variation of He I found previously. However, the wavelength measurements do not exhibit variations similar to those found for He i; at least in the case of the Mg n line this result is difficult to reconcile with the rigid rotator model for this star. Rapid fluctuations previously found in He i on a particular night are found to be accompanied by synchronous fluctuations in Mg ii and H7, but no significant variations in H 8, and antiphase variations in the K line. An attempt to fit a thermal model to these fluctuations was only partially successful. The variations in the Si ii and Mg ii lines are interpreted as abundance variations of 10 to 100 times the solar value in silicon, and 0.03 to 10 times the solar value in magnesium. A change in ultraviolet silicon opacity due to the change in silicon abundance with position on the stellar surface is found to be inadequate to explain the variations in H7. Key words: Ap stars - spectral variations
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