EXPLOSIVE EJECTION OF MATTER ASSOCIATED WITH STAR FORMATION IN THE ORION NEBULA

TIGHTLY collimated outflows of gas are often associated with regions of star formation; they interact with the ambient interstellar medium to produce the knots of shock-excited emission known as Herbig-Haro (HH) objects1,2. Two interpretations have been suggested for these objects: they may represent either the shocking of dense clumps of material that have been ejected into the surrounding molecular cloud3, or the interaction of stationary knots with fast, low-density jets4,5. Here we report the discovery of a complex of HH objects and associated wakes that require compact knots of material to have been ejected over a wide opening angle in a seemingly explosive event. Our observations suggest that, at least in this case, the former interpretation is correct, and they highlight the need to search other stay-forming regions in order to establish the frequency of such events.