Program: GN-2014A-Q-29

Young stars can drive powerful jets into the surrounding medium. Surprisingly, we know little about jet launching and collimation, the two fundamental mechanisms which determine the properties of these jets. In several cases strong and apparently stationary emission is observed 0.2\arcsec{} from the central star but the time-sampling in previous observations is too coarse to decide if it is transient with a period of a few months or if this feature is caused by a stationary recollimation shock. We propose to obtain a sequence of Gemini-North observations with the integral field unit NIFS to observe the evolution of the inner component of the jets from DG~Tau, RY~Tau and RW~Aur. Herbig-Haro objects in these jets move about 0.3\arcsec{}/yr, thus in about 1 year adaptive optics will reveal if the inner component is truly stationary or if we are seeing a knot in the making. Because the time scale of knot formation is linked to the dynamical time scale of the launching mechanism this observation will provide crucial contraints for future modelling.