K-line photometry of southern A stars.
Abstract
Extension of the photoelectric measurements of the strength of the calcium K4ine to 223 stars of predominantly southern or equatorial declinations and well distributed in right ascension has expanded the existent list to 369 field stars for which a k-index is available, including many more Am stars. All available k-index data for field stars are presented here. Previous conclusions regarding attribution of variations in K4ine strengths at a specific temperature to differences in calcium abundance, and assessment of that abundance variation as being about a factor of 2, are supported. Interstellar reddening probably contributes little to the scatter. A systematic overabundance of calcium that was tentatively suggested earlier may be spurious. Am stars are shown to be even more heterogeneous in their K4ine strengths than was shown previously, and the data suggest that the calcium anomaly in Am stars may be slightly moderated by evolution off the zero-age main sequence. A number of stars that probably exhibit spectral peculiarities are identified by means of K-line and intermediate-band photometry.
- Publication:
-
The Astrophysical Journal Supplement Series
- Pub Date:
- December 1971
- DOI:
- 10.1086/190245
- Bibcode:
- 1971ApJS...23..421H