The Orion star-forming complex

High-resolution images of the Orion Nebula in the millimeter wave emission lines of CS (49 GHz and 98 GHz), and CO (115 GHz) obtained with the Nobeyama telescope are presented and compared with optical, IR, and interferometric radio images. The images reveal activities associated with star formation. The images of the 49-GHz and 98-GHz lines of CS show a long and narrow N-S ridge of dense molecular gas. Two major clumps are recognized on the ridge: one is associated with the KL object, and the other is 100 arcsec south of it. The images of the 115 GHz CO line indicate interaction between the molecular cloud and the H II region, with shocks observed at the interaction between the two regions. The CO images reveal filamentary structures ('streamers') stretching radially from the KL region. They run far beyond the boundary of the molecular high-velocity flow and are accompanied by HH objects. They may manifest mostly unseen high-velocity flows driven by the activity of young stellar objects.