In this study, we present low mass to intermediate‐mass star‐forming hydrostatic cores in a self‐gravitating molecular cloud. Considering that the gravitational energy released during the collapse is the energy difference between the initial and final conditions. According to the virial theorem half the change in gravitational energy goes into internal energy the other half gets radiated away. However, half the change in gravitational energy is not completely (100%) emitted in the form of radiation. Therefore, we impose a dimensionless thermodynamic efficiency factor ϵ (where 0 < ϵ < 1) and quantify it as ϵ=4πRc2σTc4Lgf. Using these preconditions, we formulate equations of mass, density, and radius for the first hydrostatic core and the second hydrostatic core. The model shows there is a close relationship between the first hydrostatic core properties and the prestellar core properties. Moreover, the first hydrostatic core properties can influence the second hydrostatic core formation.

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The formation of stars constitutes one of the basic problems in astrophysics. Understanding star formation efficiency of molecular clouds (MCs) of a galaxy is necessary for studying the galactic evolution. Present data and theoretical formulations show that the structure and dynamics of the interstellar medium (ISM) are extremely complex. Therefore, there is no simple model that can explain adequately the star formation efficiency of MCs because of its complex nature. The initial mass of the cloud needed for collapse varies based on the environment in which the cloud resides and the strength of its magnetic field, turbulence, as well as the speed of rotation. In this paper, we estimate the star formation efficiency by combining pre-determined models and the critical mass formulated by Kumssa & Tessema (2018).

Magnetic fields are a key component in star formation theories. Nevertheless, their exact role in the formation of stars is still a matter of debate. The process of angular momentum transportation by the disturbance caused during magnetic field reconnection still needs theoretical formulation in terms of the collapsing cloud’s parameters. The purposes of this study are: to model the critical mass of a magnetized, gravitating and turbulent star forming molecular cloud (MC) and to formulate the momentum carried out by a magnetic field through magnetic field reconnection in terms of the MC’s parameters. By applying theoretical modeling, we show how angular momentum transported via an Alfvén wave can be described in terms of mass, radius and dispersion velocity of a collapsing cloud core and a model equation of the critical mass for a gravitating, turbulent, and magnetized molecular cloud core. The outflow of angular momentum by magnetic fields facilitates the inflow of mass. On the other side, magnetic pressure prevents collapse. Therefore, magnetic fields have a dual purpose in the process of star formation. This momentum outflow triggers the inflow of mass to conserve angular momentum. The results show that Alfvén waves are like a machine that extracts angular momentum from a magnetized collapsing cloud core. Thus the total angular momentum transported by magnetic field at a distance R from the core’s center depends on the size, mass and turbulent velocity dispersion of the collapsing cloud core.

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