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Title:
Disks, Microjets, Windblown Bubbles, and Outflows in the Orion Nebula
Authors:
Bally, John; O'Dell, C. R.; McCaughrean, Mark J.
Affiliation:
AA(Center for Astrophysics and Space Astronomy, Campus Box 389, University of Colorado, Boulder, CO 80309 ), AB(Department of Space Physics and Astronomy, MS-108, Rice University, P.O. Box 1892, Houston, TX 77251-1892 ), AC(Astrophysikalisches Institut Potsdam, An der Sternwarte 16, 14482 Potsdam, Germany )
Publication:
The Astronomical Journal, Volume 119, Issue 6, pp. 2919-2959. (AJ Homepage)
Publication Date:
06/2000
Origin:
UCP
Astronomy Keywords:
ISM: Individual: Name: Orion Nebula, ISM: Jets and Outflows, Stars: Formation, Stars: Pre-Main-Sequence, Stars: Winds, Outflows
DOI:
10.1086/301385
Bibliographic Code:
2000AJ....119.2919B

Abstract

New deep narrowband images of the Orion Nebula obtained with WFPC2 on the Hubble Space Telescope (HST) and spectra taken with the HIRES spectrometer at the Keck Observatory are presented. We report eight new circumstellar disks seen in silhouette against the background nebular light and about 30 dark disks embedded within the bright proplyds rimmed by ionization fronts. Deep narrowband lambda6300 Å images reveal skins of glowing [O I] emission associated with several disks embedded within bright proplyds. [O I] emission also surrounds one dark disk not surrounded by an ionization front; this object may be embedded within the photon-dominated, mostly neutral region behind the ionization front of the Orion Nebula. The intensity and morphology of the [O I] emission provides support for the photon-dominated-region models of externally irradiated circumstellar disks in which soft UV powers photoablation of the disk surface. Dozens of outflows powered by young stars have been discovered on the new images. More than 20 stellar jets emerge from the externally irradiated circumstellar disks or their associated young stars embedded within the Nebula. Most are one-sided (monopolar) subarcsecond-scale microjets, too small to be seen on ground-based images against the bright background nebular light. Additionally, wide-angle winds from 10 young stars in the outskirts of the Nebula power large-scale bow shocks facing the Trapezium OB stars. These shocks may be produced by wind-wind interactions where the T-Tauri winds interact with the outflow of plasma from the core of M42. The largest such structure, associated with the star LL Ori, contains a number of compact high-proper-motion clumps moving almost tangentially to the bow shock. The new data are combined with older HST images to determine proper motions for many nebular features. Neither the LL Ori type bow shocks in the outskirts of the nebula nor the Halpha + [O III] arcs that surround many proplyds near the Trapezium show measurable proper motions and are therefore stationary structures. However, most other bow-shaped features not centered on young stars exhibit large proper motions, with velocities ranging from 50 to 300 km s-1. The sources of many of these moving features remain unknown. The proper-motion survey of the nebular core reveals the presence of about a dozen new large-scale (>0.1 pc) outflow complexes. Many of these new outflows originate from the vicinity of the high-luminosity OMC-1S infrared and submillimeter source complex located southwest of the Trapezium. These supersonic features provide evidence that stellar outflows inject large amounts of kinetic energy into the nebula. However, a quantitative analysis indicates that their total power is small compared with the power in the plasma flowing away from the main nebular ionization front. Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555.
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