Radiative unstable modes in the jets of young stellar objects

Young stellar objects (YSOs) frequently show collimated outflows that terminate in a hot spot, usually interpreted as the bow shock originated by the head of a supersonic jet as it interacts with the external medium. In addition to this hot spot, some stellar jets present knots of emission along their axes, whose origin has been ascribed to Kelvin-Helmholtz (K-H) reflected modes evolved into shocks. We analyze, in connection to this phenomenology, the stability of an infinite cylindrical fluid beam undergoing radiative losses. We find that radiative cooling has a stabilizing effect on reflected modes, that critically depends on small variations of the temperature of the jet's matter. We also note that, along with K-H modes, a radiative jet can be made unstable by thermal instability.