A New Mid-Infrared Map of the BN/KL Region Using the Keck Telescope
- 1 July 2004
- journal article
- Published by American Astronomical Society in The Astronomical Journal
- Vol. 128 (1), 363-374
- https://doi.org/10.1086/421373
Abstract
We present a new mid-infrared (12.5micron) map of the BN/KL high-mass star-forming complex in Orion using the LWS instrument at Keck I. Despite poor weather we achieved nearly diffraction-limited images (FWHM = 0.38'') over a roughly 25'' X 25'' region centered on IRc2 down to a flux limit of ~250 mJy. Many of the known infrared (IR) sources in the region break up into smaller sub-components. We have also detected 6 new mid-IR sources. Nearly all of the sources are resolved in our mosaic. The near-IR source ''n'' is slightly elongated in the mid-IR along a NW--SE axis and perfectly bisects the double-peaked radio source ''L''. Source n has been identified as a candidate for powering the large IR luminosity of the BN/KL region (L = 10^5 L_sun). We postulate that the 12 micron emission arises in a circumstellar disk surrounding source n. The morphology of the mid-IR emission and the Orion ''hot core'' (as seen in NH_3 emission), along with the location of water and OH masers, is very suggestive of a bipolar cavity centered on source n and aligned with the rotation axis of the hypothetical circumstellar disk. IRc2, once thought to be the dominant energy source for the BN/KL region, clearly breaks into 4 sub-sources in our mosaic, as seen previously at 3.8 -- 5.0 micron. The anti-correlation of mid-IR emission and NH_3 emission from the nearby hot core indicates that the IRc2 sources are roughly coincident (or behind) the dense hot core. The nature of IRc2 is not clear: neither self-luminous sources (embedded protostars) nor external heating by source I can be definitively ruled out. We also report the discovery of a new arc-like feature SW of the BN object, and some curious morphology surrounding near-IR source ''t"Keywords
This publication has 29 references indexed in Scilit:
- Internal Velocities in the Orion Nebula: Large Proper-Motion FeaturesThe Astronomical Journal, 2002
- A Molecular Outflow Traced by S[CLC]i[/CLC]O Masers in Orion KLThe Astrophysical Journal, 1999
- High-Resolution CO Observations of the Molecular Outflow in the Orion IRc2 RegionThe Astrophysical Journal, 1996
- Explosive ejection of matter associated with star formation in the Orion nebulaNature, 1993
- Near-infrared imaging of the Becklin-Neugebauer-IRc2 region in Orion with subarcsecond resolutionThe Astrophysical Journal, 1993
- A model of the chemistry in hot molecular coresMonthly Notices of the Royal Astronomical Society, 1988
- Molecular abundances in OMC-1 - The chemical composition of interstellar molecular clouds and the influence of massive star formationThe Astrophysical Journal, 1987
- The sub-arc second structure of IRc2 at 5 micronsThe Astrophysical Journal, 1984
- Outflow of Matter in the KL Nebula - the Role of IRC2The Astrophysical Journal, 1981
- Observations of an Infrared Star in the Orion NebulaThe Astrophysical Journal, 1967