Fragmentation (Interstellar Clouds)

Synonyms

Star formation

Definition

The dense cores that form stars through gravitational collapse are embedded in much larger and more rarefied expanses of gas. How the parent molecular cloud produces its substructure of dense cores is the problem of fragmentation. The traditional view is that the parent cloud breaks apart as it collapses in on itself. In numerical simulations, objects resembling dense cores are created in turbulent, collapsing clouds. However, there is little evidence that large clouds are indeed collapsing. If they are not, but are at least temporarily stable, then dense cores must be produced in another fashion, perhaps by the slow accretion of background gas.

Overview

The interstellar clouds that contain young stars are relatively small structures embedded within more diffuse background gas. These dense cores have sizes of about 0.1 parsec, and masses comparable to that of the Sun. The diffuse parent bodies, known as dark clouds or clumps, have sizes larger by two...