Science. 1991 Apr 19;252(5004):389-96. doi: 10.1126/science.252.5004.389.
Astrophysical jets are linear structures associated with stars and galaxies which span about seven orders of magnitude in size; the largest jets emanating from galaxies are about 100 times the size of our galaxy and are the largest single objects in the universe. Jets associated with stars are composed of ionized gas moving away from the star with velocities of a few hundred kilometers per second. Extragalactic jets are composed of relativistic particles, magnetic field, and probably additional amounts of cooler ionized plasma either originally ejected in the jet or entired by it out of the surrounding gaseous medium. The initial outflow velocity for extragalactic jets may be relativistic, and average outflow speeds of several thousand kilometers per second are likely. The energy flux carried by extragalactic jets may be in excess of 10(46) ergs per second, depending upon the nature of the jet. A definition of jet properties, deduced from their interaction with the ambient medium, can place essential constraints on models for the central power source in the parent galaxy or quasi-stellar object where they originate.
天体物理喷流是与恒星和星系相关的线性结构，其大小跨越了七个数量级；最大的星系喷流大约是我们星系的 100 倍，是宇宙中最大的单一物体。与恒星相关的喷流由以每秒几百公里的速度远离恒星的电离气体组成。河外喷流由相对论性粒子、磁场以及可能还有更多的较冷电离等离子体组成，这些等离子体最初是在喷流中被喷射出来的，或者是从周围气态介质中被整个喷流带出来的。河外喷流的初始流出速度可能是相对论性的，平均流出速度可能在几千公里每秒左右。河外喷流携带的能量通量可能超过每秒 10(46)尔格，这取决于喷流的性质。从喷流与周围介质的相互作用中推断出的喷流性质的定义，可以对它们起源的母体星系或类星体中心功率源的模型施加基本限制。
