The kinematics of the magnetized protostellar core IRAS15398-3359

Context. Observations of protostellar envelopes are essential in order to understand better the process of gravitational collapse toward star and planet formation. From a theoretical perspective, magnetic fields are considered an important factor during the early stages of star formation, especially during the main accretion phase.Aims. Our aim is to study the relation between kinematics and magnetic fields at a very early stage of the star formation process by using data from the Atacama Pathfinder EXperiment (APEX) single-dish antenna with an angular resolution of 28".Methods. We observed the two molecular lines (CO)-O-18 (2-1) and DCO+ (3-2) toward the Class 0 young stellar object IRAS15398-3359. We implemented a multi-component Gaussian fitting on the molecular data to study the kinematics. In addition, we used previous polarization observations on this source to predict the influence of the magnetic field on the core.Results. The velocity gradient along the central object can be explained as an ongoing outflow motion. We report the flowing of material from the filament toward the central object, and the merging of two velocity components in the (CO)-O-18 (2-1) emission around the protostar position, probably due to the merging of filamentary clouds. Our analysis shows that the large-scale magnetic field line observed previously is preferentially aligned to the rotation axis of the core.