An unusual star of spectral type B, but with weak helium lines (hence the suffix ‘w’) that make classification difficult; also known as a helium-weak or helium-poor star. Bw stars are found in the spectral range B2–7, and may also show enhanced lines of silicon or of mercury and manganese. Many are variable. They appear to be related to Ap and Bp stars.
Subjects: Astronomy and Astrophysics.