Spectrum Variations in the Ap-Type Stars. I. A Survey of Stars Between 7^{h} and 19^{h} Right Ascension
Abstract
Repeated spectrographic observations at dispersions of 11 A and 17 A mm-1 were made of 29 Ap stars located between right ascensions 7h and 19h, and north of declination - 40 . Manganese-type Ap stars were excluded from the survey. The Ap classification of seven of the stars was not confirmed, but of the remaining 22, exactly half proved to be spectrum variables, on the basis of visual inspection of the spectrograms. Equivalent-width measurements were made for the spectrum variables in order to provide quantitative indicators of variability. Examination of the Ap stars in Babcock's list of magnetic stars shows that of those sufficiently well observed to determine variability, 47% are spectrum variables, in agreement with the results of the present observations. The data available are insufficient to determine correlations between the type and degree of spectrum variability and the other properties of the Ap stars. Key words: peculiar A stars - spectrum variables
- Publication:
-
Publications of the Astronomical Society of the Pacific
- Pub Date:
- August 1974
- DOI:
- 10.1086/129624
- Bibcode:
- 1974PASP...86..408B