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Studies of dust grain properties in infrared reflection nebulaeA model has been developed for reflection nebulae around luminous IR sources embedded in dense dust clouds. The shape of the IR spectrum is shown to be the result of a combination of the scattering properties of the dust, the spectrum of the illuminating source, and foreground extinction, while geometry plays a minor role. Comparison of the model results with IR observations of the reflection nebula surrounding OMC-2/IRS 1 shows that either a grain size distribution like that found in the diffuse ISM, or consisting of larger grains, can explain the observed shape of the spectrum. However, the absolute intensity level of the scattered light, as well as the observed polarization, requires large grains. By adding water-ice mantles to the silicate and graphite cores, the 3.08 micron ice-band feature observed in the spectra of several IR reflection nebulae has been modeled. It is shown that this ice band arises naturally in optically thick reflection nebulae containing ice-coated grains.
Document ID
19900035506
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Pendleton, Y. J.
(NASA Ames Research Center Moffett Field, CA, United States)
Tielens, A. G. G. M.
(NASA Ames Research Center Moffett Field, CA, United States)
Werner, M. W.
(NASA Ames Research Center Moffett Field, CA, United States)
Date Acquired
August 14, 2013
Publication Date
January 20, 1990
Publication Information
Publication: Astrophysical Journal, Part 1
Volume: 349
ISSN: 0004-637X
Subject Category
Astrophysics
Accession Number
90A22561
Distribution Limits
Public
Copyright
Other

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