 |
|
| EPoS Contribution |
|
Sequential onset of collapse at different scales in hierarchically collapsing molecular clouds. Implications for fragmentation studies.
Enrique Vazquez-Semadeni IRyA/UNAM, Morelia, MX | |
| Under the Global Hierarchical Collapse Scenario (GHC) for molecular clouds (MCs), the clouds are undergoing global gravitational contraction, causing their mean density to increase. As a consequence, the mean Jeans mass in the clouds decreases, causing smaller mass scales to initiate their collapse at later times. We discuss a first-order approximation to determine the times of the onset of collapse as a function of mass scale, and how this mechanism allows an interpretation of the fragmentation studies in dense cores. These studies indicate that the number of fragments scales proportionally to the number of Jeans masses in the cores, but with a relatively small efficiency. The delay introduced by the sequential onset of collapse suggests that the low efficiency factor may be due at least in part to the fact that the relevant Jeans mass for the present number of fragments is the Jeans mass of the core at an earlier time. | |
 | |
| Caption: Time for destabilization (i.e. onset of collapse) of a fragment of mass M for various values of the turbulent Mach number, Ms. The time and mass are, respectively, normalized to the free-fall time and the Jeans mass at the mean initial density. | |
| Collaborators: A. Palau, IRyA/UNAM, MX |
Key publication
Suggested Session: Cores |