Recent Hubble Space Telescope images have allowed the determination with unprecedented accuracy of motions and changes of shocks within the inner Orion Nebula. These originate from collimated outflows from very young stars, some within the ionized portion of the nebula and others within the host molecular cloud. We have doubled the number of Herbig–Haro objects known within the inner Orion Nebula. We find that the best-known Herbig–Haro shocks originate from relatively few stars, with the optically visible X-ray source COUP 666 driving many of them. While some isolated shocks are driven by single collimated outflows, many groups of shocks are the result of a single stellar source having jets oriented in multiple directions at similar times. This explains the feature that shocks aligned in opposite directions in the plane of the sky are usually blueshifted because the redshifted outflows pass into the optically thick photon-dominated region behind the nebula. There are two regions from which optical outflows originate for which there are no candidate sources in the SIMBAD database.

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Published in The Astrophysical Journal, v. 150, no. 4, article 108, p. 1-63.

© 2015. The American Astronomical Society. All rights reserved.

The copyright holders have granted the permission for posting the article here.

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G.J.F. acknowledges support by NSF (0908877; 1108928; and 1109061), NASA (10-ATP10-0053, 10-ADAP10-0073, and NNX12AH73G), JPL (RSA No 1430426), and STScI (HST-AR-12125.01, GO-12560, and HST-GO-12309). M.P. received partial support from CONACyT grant 129553. W.J.H. acknowledges financial support from DGAPA–UNAM through project PAPIIT IN102012. C.R.O.'s participation was supported in part by HST program GO 12543.