MASS-LOADED RELATIVISTIC JETS

The stars of the parent galaxies inject matter into extragalactic jets in the form of stellar winds. From the present-day estimated mean mas s-loss rate by stars in ellipticals, M = 10(-12) M. yr-1, we can infer that the mass injected is high enough to slow the jets of weak FR-1 r adio sources down to subrelativistic velocities, but not FR-II jets. T his deceleration overcomes the apparent contradiction between the unif ication scheme for FR-Is and BL Lacs and the low velocities of FR-I je ts at kiloparsec scales. In this paper the interaction between a relat ivistic e--e+ jet and stellar winds is considered, and the conditions under which total mixing is achieved are found. A quasi-one-dimensiona l approximation of the fluid model with a smoothly distributed source of mass is used to study the dynamics of these mass-loaded jets in a g alaxy with a King distribution of stars and a Hubble distribution of i ntergalactic gas. The solutions found can qualitatively explain the be haviour of the FR-1 jets near their 'gaps', but underestimate the obse rved lengths of the gaps. It is proposed that the development of a tur bulent boundary may be crucially important in the dynamics of the FR-I jets.