Abundances of calcium for a sample of 57 classical AM stars.
Abstract
Abundances of calcium, log N(Ca), are derived for a fairly complete sample of 57 single-lined classical Am stars. Published photoelectric measures of the CaII K-line at 3933 A and K-line spectral types are used to determine the equivalent widths of the K-line for a differential curve-of-growth comparison of the Am stars with the standard stars 15 Vul and 28 And. On a scale with log N(H) = 12.0, the values of log N(Ca) for the Am stars range from 5.5 to 6.5, the solar value being 6.36. The Am stars with low abundances of calcium have a small range of the modified age parameter, and absolute magnitudes within about 1.3 mag of the zero-age main sequence, whereas the other Am stars and normal stars have a larger spread in age. These results are probably consistent with the suggestion that the Am phenomenon is due to subphotospheric separation of elements by diffusion in slowly rotating A-type stars.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- May 1987
- DOI:
- 10.1093/mnras/226.2.361
- Bibcode:
- 1987MNRAS.226..361G
- Keywords:
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- A Stars;
- Abundance;
- Calcium;
- Metallic Stars;
- Stellar Composition;
- Stellar Spectra;
- Electrophotometry;
- K Lines;
- Spectral Line Width;
- Astrophysics