# What is the difference between wind, jet and outflow?

For jets, I found a pdf file here

Jet: collimated beam of matter of high velocity

sources: young stars, active galactic nuclei, $\mu$-quasars, gamma­ ray bursts, planetary nebulae, pulsars

jet sources host accretion disks

How about winds and outflows? Can somebody make some clarifications for the three concepts， their correlation and difference?

• Wind is usually a stellar wind, i.e. an isotropic flux of charged particles emitted by a start (the sun also ejects a wind). A jet is produced by the system of accretion disc + protostar and is a highly collimated and very fast beam of ionized matter ejected in a bi-polar fashion. This jet collides with the (dense and neutral) ambient medium and accelerates those gas particles. They form an outflow (often bi-polar, and much less collimated) and are visible in emission of the accelerated gas, usually CO, Sep 11 '18 at 12:49
• @Roellig so both wind and jet are outflows? A disk is not necessary for wind, right? Sep 11 '18 at 13:02
• Right. No need for a disk to produce winds. Sep 12 '18 at 11:21

## 1 Answer

I'm not sure there are very clear official definitions, but here is my take on accepted usage in the star formation community:

Outflows - general term describing both winds and jets.

Jets - collimated outflows along magnetic poles.

Winds - outflow from the stellar surface in all directions, not just along the poles.

Stellar winds are what comes from individual bright stars. Jets can be protostellar jets from young stars, or on a larger scale from galactic nuclei.