pre-main-sequence star
(PMS, pre-MS, PMS object)
(star not yet with a nuclear reaction)
A pre-main-sequence star (PMS or pre-MS or PMS object)
is a star in an early stage after being a protostar and
before becoming a main sequence star, in other words,
before its hydrogen burning.
At this early point, the star's energy is from gravitational
contraction.
Some types:
- T-Tauri star (TTS).
- FU Orionis star (FUor).
- Herbig Ae/Be star (HAeBe) or more specifically: Herbig Ae star (HAe) or Herbig Be star (HBe).
- UX Orionis variable (UXOR), a Herbig Ae/Be star that shows variability seeming to be temporarily obscured by dust.
Two distinctions used to classify pre-main-sequence
stars and protostars are:
- whether it is still accreting material.
- whether it is still surrounded by a nebula.
Active pre-main-sequence stars often emit
X-rays and ultraviolet rays.
(star type,stellar evolution,protostars)
Further reading:
http://en.wikipedia.org/wiki/Pre-main-sequence_star
Referenced by pages:
chondrite
evolutionary track
FU Orionis star (FUor)
G-type star (G)
gravitational collapse
Hayashi track
Henyey track
infrared excess (IRX)
K-type star (K)
main sequence star (MS)
protostar
spectral class
stellar evolution
T-Tauri star (TTS)
X-ray source
young stellar object (YSO)
Index