Rotational support $\left(\rho v_{\varphi }^2/2>2P_{\text{th }}\right)$ at different time snapshots during the 1 M_⊙ pre-stellar core collapse. The topmost plot shows the presence of both discs, which eventually merge after the outflow is launched. The white vertical line marks the radius of the rotationally supported first core disc or merged disc using the definition detailed in Sect. 3.1. A thermal pressure driven outflow is also seen to transport dust from the inner regions. A selected sample of 1 µm (green), 10 µm (orange), and 100 µm (blue) dust from within the young protostellar disc that move radially outwards and/or above the midplane are overplotted. The gas velocity streamlines indicate the material falling onto the disc, mixing within the two discs, and outflowing. The size-independent wellcoupled dust follows the gas motion in all the different regions.