A train of shocks at 3000-au scale? Exploring the clash of an expanding bubble into the NGC 1333 IRAS 4 region. SOLIS XIV

ABSTRACT There is evidence that the star formation process linked to intricate net of filaments in molecular clouds, which may be also due gas compression from external triggers. We studied southern region Perseus NGC 1333 cloud, known heavily shaped by similar triggers, shed light on perturbed filament where Class 0 IRAS4 protostars lie. use new IRAM-NOEMA observations SiO and CH3OH, both trace violent events as shocks, towards IRAS 4A part Large Program Seeds Of Life In Space (SOLIS). detected three parallel elongated (>6000 au) structures, called fingers, with narrow-line profiles (?1.5 km s?1) peaked at cloud systemic velocity, tracing high density ((5–20) × 105 cm?3) temperature (80–160 K). They are chemically different, northern finger traced CH3OH ([CH3OH]/[SiO] ? 160–300), while other two only ? 40). Among various possibilities, a train distanced ?5000 yr, would consistent if substantial fraction silicon, frozen grain mantles, released shocks. suggest shock an expanding bubble, coming behind south-west clashing against lies. Finally, we propose solution two-decades-long debate nature origin widespread narrow emission observed south 1333, namely it unresolved trains