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Infrared sources and excitation of the W40 complex
Smith, J.; Bentley, A.; Castelaz, M.; Gehrz, R. D.; Grasdalen, G. L.; Hackwell, J. A.
AA(Wyoming Infrared Observatory, Laramie, WY), AB(Wyoming Infrared Observatory, Laramie, WY), AC(Wyoming Infrared Observatory, Laramie, WY), AD(Wyoming Infrared Observatory, Laramie, WY), AE(Wyoming Infrared Observatory, Laramie, WY), AF(Wyoming Infrared Observatory, Laramie, WY)
Astrophysical Journal, Part 1 (ISSN 0004-637X), vol. 291, April 15, 1985, p. 571-580. NSF-USAF-supported research. (ApJ Homepage)
Publication Date:
NASA/STI Keywords:
Early Stars, Infrared Spectra, Interstellar Matter, Molecular Clouds, Astronomical Photometry, Cosmic Dust, Cosmic Plasma, Emission Spectra, H Ii Regions, Molecular Excitation, Stellar Envelopes, Stellar Evolution
Bibliographic Code:


Infrared images and photometry are presented for the W40 molecular cloud and H II region complex. The images, sampled through a 5 arcsec aperture and observed at effective wavelengths of 2.3, 3.6, 4.9, 10.0, and 19.5 microns, reveal only unresolved sources clustered near the peak of thermal H II emission. Six of the seven detected sources coincide with faint but optically observable stars. The photometry suggests that the three brightest sources are heavily obscured early-type stars surrounded by infrared emitting circumstellar materials. In some cases, much of the compact infrared emission may be produced by circumstellar condensations. The three brightest sources (IRS 1a, 2a, and 3a) are candidates for producing the level of excitation inferred for both the dust and H II plasma of the W40 complex. Observed circumstellar dust has a negligible effect on the excitation of the W40 region. Instead, the predominant mode of excitation, whereby radiant luminosities of the exciting stars are absorbed by the W40 dust, appears to involve only diffuse dust mixed with the molecules, atoms and plasma.

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