Astrophysical Jets

I show that the assumption that the acceleration and collimation mechanisms of jets are the same in all the classes of astrophysical objects which are observed to produce jets, can lead to interesting conclusions. Jets have now been observed in: active galactic nuclei, young stellar objects, massive x-ray binaries, low mass x-ray binaries, black hole x-ray transients, gamma-ray bursts, symbiotic systems, planetary nebulae, and supersoft x-ray sources, and possibly recurrent novae and pulsars. An attempt is made to identify the necessary ingredients for the acceleration and collimation mechanisms. I show that most likely: jets are produced at the center of accretion disks, and are accelerated and collimated hydromagnetically.