The core of a formerly massive star (originally more than 12 solar masses) which has evolved and lost its hydrogen-rich envelope. Hydrogen loss can happen either through a strong stellar wind, as in Wolf–Rayet stars, or by mass transfer on to a companion, as in a close binary. A helium star is expected to evolve exactly as the core of a massive star would: by producing an iron core which collapses to cause a Type Ib or Ic supernova explosion, depending on the mass of the star. ‘Helium star’ is also an obsolete term for a normal B-type star.
Subjects: Astronomy and Astrophysics.