steps to starbirth

the starbirth process:
5 steps from interstellar cloud to a main-sequence star

phase object name time scale size # known

A) free-fall collapse of a spherical cloud
triggered by molecular cooling or shock wave squeezing
cores
of GMCs
globules
10⁴ yr 10⁵ au ~
1 c-yr
1 (B335)

B) a flattened disk forms, with bipolar jets/winds
Herbig-Haro
objects 10⁵ yr 1000 au ~ 100

C) jets/winds disappear,
leaving only a disk
T Tauri stars 10⁶ yr many hundreds

D) the disk slowly disappears, as planet building commences
Orion proplyds 10⁷ yr 100 au 5 (e.g. beta Pic)

E) a main sequence star is formed, perhaps surrounded by a planetary system
10⁸ - 10⁹ yr 10 au (~200 sun-like stars with planets)

phase	object name	time scale	size	# known

A) free-fall collapse of a spherical cloud triggered by molecular cooling or shock wave squeezing	cores of GMCs globules	10⁴ yr	10⁵ au ~ 1 c-yr	1 (B335)

B) a flattened disk forms, with bipolar jets/winds	Herbig-Haro objects	10⁵ yr	1000 au	~ 100

C) jets/winds disappear, leaving only a disk	T Tauri stars	10⁶ yr		many hundreds

D) the disk slowly disappears, as planet building commences	Orion proplyds	10⁷ yr	100 au	5 (e.g. beta Pic)

E) a main sequence star is formed, perhaps surrounded by a planetary system		10⁸ - 10⁹ yr	10 au	(~200 sun-like stars with planets)