A peculiar star (hence the suffix ‘p’) of spectral type A that has much stronger absorption lines than normal of elements such as silicon, chromium, strontium, and europium; also known as a peculiar A star. Such stars have unusually strong magnetic fields, often thousands of times stronger than the Sun’s typical surface field. This leads to certain elements being localized in spots, similar to sunspots. As the star rotates the spectral features therefore vary. Hotter and cooler versions of Ap stars are, respectively, Bp and Fp stars. Stars with enhanced mercury, manganese, and gallium are sometimes included in the Ap class and are also known as mercury–manganese stars, but usually do not have strong magnetic fields.