2022ApJ...933L..35F

We present sensitive NH₃ (1,1)-(7,7) line images from the Karl G. Jansky Very Large Array toward successive shocks, which are associated with the blueshifted outflow lobe driven by the compact protobinary system L1157. Within a projection distance of 0.1 pc, our observations not only trace the quiescent and cold gas in the flattened envelope, but also illustrate the complex physical and chemical processes that take place where the high-velocity jet impinges on its surrounding medium. Specifically, the NH₃ ortho-to-para ratio is enhanced by a factor of 2-2.5 along the jet path, where the velocity offset between the line peak and the blueshifted wing reaches values as high as 10 km s^–1; it also shows a strong spatial correlation with the NH₃ column density, which is enhanced to >10¹⁶ cm^–2 toward the shock cavities. At a linear resolution of 1500 au, our refined temperature map from the seven NH₃ lines shows a gradient from the warm B0 eastern cavity wall (>120 K) to the cool cavity B1 and the earlier shock B2 (<80 K), indicating shock heating.