Top panel: example of a radial profile of the peak intensity T_mb of the saturated HO line at channel v_i ~ +0.6 km s⁻¹ as a functionof projected distance ρ from the nucleus in the jet (full circles). The empty circles correspond to the T_mb value for channels at v_i ~−v_exp, which saturate close to the gas temperature at the distance of the spacecraft. The dotted line shows the adopted gas temperature profile (see text). Bottom panel: same as above for the direction opposite to the jet direction (i.e., night side), using here channels at +0.45 km s⁻¹. Higher values a few kilometers from the nucleus can be interpreted as due to a lower efficiency of the cooling of the gas through adiabatic expansion.