helium star

helium star

1. One of a rare class of stars (excluding white dwarfs) whose outer layers contain more helium than hydrogen. These are evolved stars that have lost their hydrogen-rich envelope, possibly by the effect of a companion in a close binary system. Some helium stars are likely progenitors of type Ib/Ic supernovae. See also Wolf–Rayet stars.
2. Obsolete name for B star.