NUMERICAL-SIMULATION OF 2D JETS WITH TIME-DEPENDENT DIRECTION OF EJECTION

Jets from young stars often show sinuous structures or apparent change s of direction in the plane of the sky. These effects can be interpret ed as being the direct consequence of a time-dependent direction of ej ection from the source. To analyse this possible interpretation, we ha ve computed adiabatic and nonadiabatic 2D jets from sources with a tim e-dependent ejection direction. From these numerical simulations, we h ave obtained a qualitative description of the general characteristics of such flows. We have also obtained emission-line intensity maps whic h appear to share at least some of the observational characteristics o f stellar jets. A simulation of the complete structure of an adiabatic wiggling jet is presented. From it we extract information about the g eneral structure, velocities, the shock formation and evolution, knot formation and motion, and finer structure at the head of the jet. A 'c lose-up' of the body of a non-adiabatic wiggling jet is also presented . Maps of emission from this flow are calculated and compared with obs ervational data.