A main-sequence star of type B, A, or early F with abnormally strong or weak spectral lines of certain elements. Chemically peculiar (CP) stars usually have strong magnetic fields and exhibit brightness variations as they rotate as a result of patches on their surfaces of different chemical composition. The lower-case letter p is added to their spectral type (Ap, Bp), followed by chemical symbols for the most prominent elements they contain such as silicon (Si), chromium (Cr), strontium (Sr), and europium (Eu). CP stars have slow rotation rates, which is thought to contribute to the lack of chemical mixing in their outer layers. See also Am star; Ap star; Bp star; magnetic star; mercury-manganese star; peculiar star.