محمود قلی پور

This work aims to investigate the dynamic behavior of ambipolar diffusion during the gravitational collapse of a filamentary molecular cloud undergoing radiative cooling. The cloud undergoes collapse in the presence of the ambipolar diffusion effect while being cooled by radiation. According to the observations of CO emissions, the cooling rate is scaled as a function of density and temperature. Furthermore, in the presence of ambipolar diffusion, the profile of the toroidal magnetic field is dominated by the induction equation. The self-similar method is employed to solve the derived equations. The problem is highly sensitive to two parameters, namely the polytropic exponent 𝛾 and the ambipolar diffusivity. Accordingly, we consider the problem in three cases of the polytropic exponent. We have found that the presence of ambipolar diffusion results in a decrease in the flux-to-mass ratio at the outer regions of a cooling filament for all cases of 𝛾. However, the temperature experiences a critical increase for cases where 𝛾 > 0.8, leading to the cessation of self-similar collapse in the central regions of the cloud. The obtained results are fully consistent with previous studies regarding the star formation rate in the case of 𝛾 > 0.8. Finally, based on the results of this study, it is possible to differentiate between hot and cold gravitational collapse in a radiative cooling filament.