star formation
This page contains recent work on the formation of high-density regions within molecular clouds. The processes to form clumps and dense cores are examined by means of numerical magnetohydrodynamical simulations.


A fast magnetosonic wave can produce high-contrast density structures. Non-linear steepening of the fast mode excites slow-mode components hereby generating large density perturbations. The process, however, does not stop here. Every time the fast shock interacts with a dense region (or ridge), it again excites slow-mode waves. Dense substrucures then arise within the ridge. Similar structures are seen in molecular clouds.


In the simulation below substructures with densities higher than 100 arise in a background plasma of density 1. However, for illustrative reasons I have set the maximum value of the density to 10.



The next movie is a simulation of a fast-mode wave scattering of a pre-existing dense core [mpeg].


In cold environments such as molecular clouds, dust grains are very common. Because dust grains are very important charge and current carriers, they affect the dynamics of shocks. The next movies show how a C-type shock forms within a cold, dense cloud. Such types of shocks are associated with outflows from young stars. The first one shows the neutral density and the second the logarithm of the neutral temperature.