A star whose mass is larger than approximately 10 → solar masses.
The → spectral types of massive stars range from about B3
(→ B star) to O2 (→ O star)
and include → Wolf-Rayet stars as well as
→ Luminous Blue Variables. Massive stars are very rare;
for each star of 20 solar masses there are some 100,000 stars of 1 solar mass. Despite this
rarity, they play a key role in astrophysics. They are major sites of
→ nucleosynthesis beyond oxygen and,
therefore, are mainly responsible for the → chemical evolution
of galaxies. Due to their high ultraviolet flux and powerful
→ stellar winds,
they bring about interesting phenomena in the → interstellar medium,
like → H II regions, → turbulence,
→ shocks, → bubbles,
and so on. Massive stars are progenitors of → supernovae
(→ type Ia, → type Ic and
→ type II), → neutron stars,
and → black holes.
The formation processes of massive stars is still an unresolved problem.
For massive stars the → accretion time scale
is larger than the → Kelvin-Helmholtz time scale.
This means that massive stars reach the → main sequence while
→ accretion is still going on.
See also: → massive; → star.
