The environmental imprint on molecular layering in the dusty streamer of M512

Protostellar streamers are elongated structures that channel material from larger scale onto disks, influencing their physical and chemical evolution. The M512 protostar in Orion/Lynds 1641 hosts one of the most massive and extended streamer discovered so far, offering a unique opportunity to study these processes. We investigated the morphology, chemistry, and origin of this streamer, along with its potential impact on the protostellar disk. Using archival ALMA observations of C 18 O, DCO + , N 2 D + , and HCO + , we compared their spatial distributions through moment maps and spatial profiles. The streamer shows clear chemical stratification: C 18 O lies on the western side of the protostar, N 2 D + is farther out to the east, and DCO + is in the middle. This suggests that the structure has been shaped by environmental effects, rather than tracing a single coherent infalling flow, with only the densest gas near the protostar likely to accrete onto the disk. Overall, the bulk of the streamer reflects the physical and chemical imprint of the surrounding cloud, highlighting the importance of environmental shaping in interpreting streamer–disk connections and their role in disk growth.