Multiple shocks around the low-luminosity protostar IRAS 16293-2422

Using the IRAM 30 m and SEST 15 m telescopes we mapped an area covering 300 " x 220 " around IRAS 16293-2422 in the N2H+ J = 1 -->0, H2CO J = 3(1,3) - -> 2(1,2), SiO J = 2 --> 1 J = 3 --> 2 and J = 5 --> 4 molecular transition s. Five positions were also observed in the FIR, between 45 mum and 200 mum , with the Long Wavelength Spectrometer on board ISO, revealing only [C II] 158 mum and[O I] 63 mum emission. All these observations are used to recon struct the complex morphology of the region, in which several outflows from several sources co-exist. The N2H+ line emission is strong and centered on 16293E, a recently discovered low mass and very young protostar situated S outh-East of IRAS 16293-2422. Only weaker N2H+ line emission is associated with the binary system IRAS 16293-2422, presumably because the gas surround ing it is warmer. In addition to the previously known North-East-South-West outflow powered by IRAS 16293-2422, we suggest the existence of a second o ut ow in this binary system. We also report the discovery of a North-West-S outh-East flow driven by 16293E. The impact of the outflows with the ambien t cloud is probed by the SiO and H2CO maps, which reveal the presence of at least four, possibly six shocked regions. We discuss in some detail the na ture of the shocks, deriving densities, temperatures and column densities o f the shocked gas of the various observed components. We suggest that the w ind and ambient shocks are probed by the high and low velocity components o bserved in the SiO lines. The morphology of the H2CO, SiO and [O I] line em issions are rather different, showing almost all kind of combinations. We d iscuss the origin of these differences in terms of the age of the shocks, t he pre-shock densities and of the composition of the ices which are partial ly desorbed by the shocks.