An Etymological Dictionary of Astronomy and Astrophysics

A very fast moving, → collimated beam of → ionized gas at high temperatures associated with most classes of compact objects that spin and/or accrete matter from their surroundings, such as → protostars, → X-ray binary systems, and, at a larger scale, with → active galactic nuclei, → gamma-ray bursts, and → quasars. In general, jet sources host → accretion disks and are associated with → magnetic fields. Astrophysical jets, despite their different physical scales and power, are morphologically very similar, suggesting a common physical origin. For example, in one extreme, → active galactic nuclei jets have typical sizes ≥ 10⁶ pc, velocities near that of light c, and parent sources (→ massive black holes) with masses 10^6-9&nbsp Msun and luminosities ~ 10^43-48Lsun; while in the other extreme, → young stellar objects jets have typical sizes ≤ 1 pc, velocities ≤ 10^-3 c,
and emerge from low mass protostars with masses ~ 1 Msun and luminosities (0.1-2 × 10⁴) Lsun. Jets play an important → feedback role in the evolution of their host systems. See also: → jet launching.

See also: → astrophysical; → jet.