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Processing of Icy Mantles in Protostellar EnvelopesThe 4.5-4.8 micron spectral region provides two potential diagnostics of radiative or thermal processing of interstellar ices in the environs of embedded stars in molecular clouds. A broad absorption feature centered at 4.62 micron is seen in the spectra of several young stellar objects (YSO's) and attributed to C-N triple bonds in a nitrile or isonitrile. As CN-bearing solids in the laboratory are produced by energetic radiative processing of ices containing nitrogen, detection of this feature in YSO's is taken as evidence for (1) the presence of nitrogen in the unprocessed cloud ices, and (2) evolution of the ice in the vicinity of the embedded source. The adjacent feature at 4.67 micron, identified with solid CO, provides not only quantitative information on CO itself but also indirect evidence for the presence of other species; its position and profile are sensitive to the molecular environment of the CO molecules in the ice mantle, and may be used to constrain both the composition and thermal/radiative history of the ice. One important example is the possibility to detect CO2, which is produced easily in the laboratory by UV irradiation of CO-rich or CH3OH-rich ices. CO embedded in a CO2 matrix gives a characteristic spectral signature distinct from other CO-bearing mixtures investigated to date. We have obtained CO absorption profiles of three young stellar objects in order to investigate their ice mantle composition.
Document ID
Acquisition Source
Ames Research Center
Document Type
Conference Paper
Chiar, J. E.
(Rensselaer Polytechnic Inst. Troy, NY United States)
Whittet, D. C. B.
(Rensselaer Polytechnic Inst. Troy, NY United States)
Gerakines, P. A.
(Rensselaer Polytechnic Inst. Troy, NY United States)
Boogert, A. C. A.
(Kapteyn Astronomical Lab. Groningen, Netherlands)
Adamson, A. J.
(University of Central Lancashire, Preston Lancashire, United Kingdom)
Date Acquired
August 17, 2013
Publication Date
October 1, 1996
Publication Information
Publication: From Stardust to Planetesimals: Contributed Papers
Subject Category
Accession Number
Distribution Limits
Work of the US Gov. Public Use Permitted.
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