Chemically peculiar stars
Helium-poor stars
Helium weak stars
He-weak stars
CP4
Helium poor stars
Helium-weak stars
Chemically peculiar stars with very weak helium lines. Examples include 3 Sco, HD 176582, HD 217833, HR 2949, and HD 21699. The He-weak stars do not form a homogeneous group. Some of them display intense Si, or Ti and Sr lines, and are considered a hot extension of the magnetic Ap/Bp stars. Others show overabundances of P and Ga, typically noted for HgMn stars. The star HD 139160 belongs to the non-magnetic subgroup of He-weak stars.
BW stars