Flow of gas in Barnard 5

We fit multiple Gaussian components to the lines so as to decompose their individual physical components. We investigated the HC3N velocity gradients to determine the direction of chemically fresh gas flow. At envelope scales, we used a clustering algorithm to disentangle the different kinematic components within H_2_CO emission.

At dense core scales, HC_3_N traces the infall from the B5 region toward the filaments. HC_3_N velocity gradients are consistent with accretion toward the filament spines plus flow along them. We found a ~2800 au streamer in H_2_CO emission, which is blueshifted with respect to the protostar and deposits gas at outer disk scales.

The strongest velocity gradients at large scales curve toward the position of the streamer at small scales, suggesting a connection between both flows. Our analysis suggests that the gas can flow from the dense core to the protostar. This implies that the mass available for a protostar is not limited to its envelope, and it can receive chemically unprocessed gas after the main accretion phase.