NGC 1333/IRAS 4: a multiple star formation laboratory

We present SCUBA observations of the protomultiple system NGC 1333/IRAS 4 a t 450 and 850 mum. The 850-mum map shows significant extended emission whic h is most probably a remnant of the initial cloud core. At 450 mum, the com ponent 4A is seen to have an elongated shape suggestive of a disc. Also we confirm that, in addition to the 4A and 4B system, there exists another com ponent 4C, which appears to Lie out of the plane of the system and of the e xtended emission. Deconvolution of the beam reveals a binary companion to I RAS 4B. Simple considerations of binary dynamics suggest that this triple 4 A-4BI-4BII system is unstable and will probably not survive in its current form. Thus IRAS 4 provides evidence that systems can evolve from higher to lower multiplicity as they move towards the main sequence. We construct a m ap of spectral index from the two wavelengths, and comment on the implicati ons of this for dust evolution and temperature differences across the map. There is evidence that in the region of component 4A the dust has evolved, probably by coagulating into larger or more complex grains. Furthermore, th ere is evidence from the spectral index maps that dust from this object is being entrained in its associated outflow.