SX Arietis star

An SX Arietis star is a type of rotating variable of spectral type B0p to B9p with an uneven surface distribution of helium and a strong magnetic field. As SX Arietis stars rotate, the amount of helium seen in the spectrum and the intensity of the magnetic field appears to vary, while the brightness changes by about 0.1 magnitude. These stars, also called helium variables, are high-temperature versions of the Alpha2 Canum Venaticorum stars.