(PMS, PMS object)
(star not yet with a nuclear reaction)
A pre-main-sequence star (PMS 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
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)
FU Orionis star (FUor)
main sequence star (V)
T-Tauri star (TTS)
X-ray source (RS)
young stellar object (YSO)