Spectral Classification of A-Type Spectroscopic Binaries

MR spectral types have been determined or are quoted for ninety-eight of 101 known spectroscopic binaries with primaries in the range A2-F3. Half of these stars are metallic-line (Am) stars; most of the remainder are outside the domain (approximately A4-F1 IV, V) of the Am stars. The remaining nine normal stars in the domain have periods of either less than 2.5 or more than about 100 days. It is con- cluded that all stars in the range A4-F1, IV, V that are primaries of binaries with periods of approximate- ly 2.3-100 days have metallic-line spectra