Abundances of calcium for a sample of 57 classical Am stars

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 Ca II 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 age parameter given by uvby β photometry is modified to take account of metallicity and rotation, and the modified age parameter is determined for the Am stars and for normal stars with similar effective temperatures. (author)