Shocks in the surroundings of the NGC 1333 IRAS 4 system

The IRAS 4A system is part of the southern filament Perseus NGC 1333 molecular cloud. As most star forming regions, known to be heavily shaped by external triggers, such as shock fronts around OB stars or supernovae remnants, cloud-cloud collisions, and instabilities. Recently, it has been hypothesized that entire southwest region 1333, encompassing where lie, due a colliding “turbulent” cell, clash triggered birth protostars on filaments. However, no specific signatures have reported so far, leaving unanswered how energy this clash, if real, dispersed. To answer question, we analyzed new high spatial resolution (~600 au) observations CH3OH SiO, tracers, obtained in context Large Program IRAM/NOEMA SOLIS searching for signature event. We detected three parallel elongated structures, called fingers, with narrow line profiles (~1.5 km s −1 ), peaked at systemic velocity cloud, tracing gas density (5-20×10 5 cm −3 ) temperature (80-160 K). They are chemically different northern finger traced both SiO CH 3 OH other two only SiO. Among various possibilities, train consecutive shocks, an expanding bubble coming behind from southwest, can reproduce observations. Finally, propose solution two-decades long debate nature origin widespread emission observed south namely unresolved trains shocks.