Effect of the magnetic field on the early collapse phase of a dense protostellar cloud -

Abstract

The purpose of this study is to investigate the role of magnetic field on the first collapse of rotating molecular clouds. The process of ambipolar diffusion has been considered and analyzed. Order of magnitude estimates are presented to justify the use of the ideal MHD approach to study the initial collapse phase in our work. As a first step, an isothermal magnetized and rotating sphere of uniform density was considered. More realistic initial conditions were used consisting of a centrally condensed cloud with a barotropic equation of state. A small perturbation was introduced to the clouds and a three-dimensional MHD code was used to study the effect of the variable magnetic field strengths suggested by observations. The results obtained in this work suggest that the magnetic field is a supporting agent against gravitational collapse as expected. Furthermore, the initial strength of the magnetic field determines whether the stellar cloud undergoes fragmentation into multiple objects. We propose some ideas for future work taking the advantage of multidimensional simulation. In particular, it is interesting to study the process of star formation under the conditions leading to the formation of the first stars in the universe.