Term: | Am stars |
Definition: |
A chemically peculiar A- or early F-type star showing an overabundance of heavy elements and an underabundance of calcium and scandium. An Am star cannot receive a unique spectral type, as different methods (using the metallic lines, the hydrogen Balmer lines, and the calcium Ca II K-lines) yield three different spectral types. Contrarily to Ap stars, Am stars do not have significant external magnetic fields. Their rotational velocities are about 100-120 km s-1 smaller than those of Ap stars. |