Seeds of Life in Space (SOLIS). IX. Chemical Segregation of SO(2)and SO toward the Low-mass Protostellar Shocked Region of L1157

We present observations of SO and SO(2)lines toward the shocked regions along the L1157 chemically rich outflow, taken in the context of the Seeds of Life in Space IRAM Northern Extended Millimeter Array Large Program, and supported by data from the Submillimeter Array and IRAM-30 m telescope at 1.1-3.6 mm wavelengths. We simultaneously analyze, for the first time, all of the brightest shocks in the blueshifted lobe, namely, B0, B1, and B2. We found the following. (1) SO and SO(2)may trace different gas, given that the large(-scale) velocity gradient analysis indicates for SO(2)a volume density (10(5)-10(6) cm(-3)) denser than that of the gas emitting in SO by a factor up to an order of magnitude. (2) Investigating the 0.1 pc scale field of view, we note a tentative gradient along the path of the precessing jet. More specifically, chi(SO/SO2) decreases from the B0-B1 shocks to the older B2. (3) At a linear resolution of 500-1400 au, a tentative spatial displacement between the two emitting molecules is detected, with the SO peak closer (with respect to SO2) to the position where the recent jet is impinging on the B1 cavity wall. Our astrochemical modeling shows that the SO and SO(2)abundances evolve on timescales less than about 1000 years. Furthermore, the modeling requires high abundances (2 x 10(-6)) of both H2S/H and S/H injected in the gas phase due to the shock occurrence, so prefrozen OCS only is not enough to reproduce our new observations.