|
Introduction to
Astrophysics and Cosmology
|
|
STAR FORMATION
Star formation in the current universe begins inside what are known as molecular clouds. Molecular clouds are a type of interstellar cloud whose density and size becomes such that formation of molecular hydrogen, H2, is allowed. Spanning over 100 light years across, propagation of star formation is caused by the pressure of the hot, ionized gas surrounding nearby stars compressing the material near the edge of the molecular cloud, initiating a gravitational collapse which will lead to the formation of more stars.
|
|
The diagram here illustrates the steps following the collapse of the molecular cloud.
(a) Dense cores form within a molecular cloud.
(b) A protostar with a surrounding disk of material forms at the center of a dense core, accumulating additional material from the molecular cloud through gravitational attraction.
(c) A stellar wind breaks out, but it is confined by the disk to flow out along the two poles of the star.
(d) Eventually this wind sweeps away the cloud material and halts the accumulation of additional material, and a newly formed start, surrounded by a disk, becomes observable.
|
|
|
|