AAS Meeting #194 - Chicago, Illinois, May/June 1999
Session 68. The Young Ones 1: Star Formation, Disks and Jets
Display, Wednesday, June 2, 1999, 10:00am-6:30pm, Southwest Exhibit Hall

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[68.12] Microjets, Wind Bubbles, and Proto-Planetary Disks in the Orion Nebula Cluster

J. Bally (CASA, University of Colorado), C. R. O'Dell (Rice University), M. McCaughrean (Potsdam), R. Sutherland (ANU)

New, deep, narrow-band images of the Orion nebula obtained with WFPC2 on the Hubble Space Telescope and the spectra obtained with the HIRES spectrometer at the Keck Observatory are presented. The new data reveal many new circumstellar disks seen in silhouette against the background nebular light. Deep narrow band \lambda6300 images reveal skins of glowing [O~I] emission associated with several disks embedded within bright proplyds. Dozens of stellar jets are seen to emerge from the protostars embedded in the Orion Nebula proplyds. Most jets are very compact, one sided (monopolar), and are sub-arcsecond scale microjets too small to be seen on ground based images, especially against the bright background nebular light. Many young stars in the outskirts of the Nebula are surrounded by large scale bow shocks facing the core of the Nebula. These structures may be produced by wide-angle stellar winds interacting with the outflow of plasma from the Nebula. The largest such structure is associated with the star LL Orionis. The new data is combined with older HST images to determine proper motions of many nebular features. In some cases the Keck radial velocities then permit determination of spatial velocities. Most of the bow shaped features exhibit large proper motions with velocities ranging from 100 to 300 km/s. The large number of supersonic features provides evidence that stellar outflows inject large amounts of kinetic energy into the nebula and may be responsible for generating chaotic and turbulent motions. Though many outflow sources are visible stars embedded within the nebula, many others lie hidden within the dense background molecular cloud.

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