The HH111 jet and multiple outflow episodes from young stars

Herbig-Haro jets are shocked beams of gas escaping supersonically from new-born stars. Here I report the discovery of an exceptionally fine jet, HH111, emerging from the young star still embedded in the Orion molecular clouds. The jet system displays four bow-shock-like features, moving in pairs in opposite directions from a 25-L solar mass infrared source. With an extent of more than 0.8 parsec, HH111 is the largest bipolar Herbig-Haro flow known. It is argued that such jets are highly transient phenomena that are related to eruptive accretion events in the build-up of the central star. (author)