Streamer Formation by Dense Core Collision

Fumitaka Nakamura  (NAOJ)

In molecular clouds, a typical dense core experiences at least one collision in its lifetime. The core collision creates a shock-compressed layer between the two cores, and the shocked gas tends to infall along the shocked layer, evolving into a streamer and spiral structure connected with the central protostars.  We show that such collision is likely to occur at several star-forming regions. For example, we found two dynamically interacting dense cores in Per-emb-2 based on the NRO 45m observations, implying that the collision induced the formation of a streamer in this protostellar core.  We then present the results of the 3D numerical simulations of core collisions, showing the streamer and spiral are created and they play a role in mass loading toward the protostars.