4. 6 micron absorption features due to solid phase CO and Cyano group molecules toward compact infrared sources

Journal Article · Sun Jan 15 04:00:00 EST 1984 · Astrophys. J.; (United States)

DOI:https://doi.org/10.1086/161642· OSTI ID:6719967

Lacy, J H; Baas, F; Allamandola, L J; van de Bult, C E.P.; Persson, S E; McGregor, P J; Lonsdale, C J; Geballe, T R

Spectra at a resolving power of 840 have been obtained for seven compact ''protostellar'' sources in the region of the 4.67 ..mu..m fundamental vibrational band of carbon monoxide. The deep absorption feature seen by Soifer et al. in W33A near 4.61 ..mu..m is shown to consist of three features: a strong broad feature at 2165 cm/sup -1/, a sharp spike at 2140 cm/sup -1/, and a ''wing'' at 2135 cm/sup -1/. The same three features are seen in other sources, but with varying relative strengths. Laboratory experiments involving UV irradiation and temperature cycling of ''dirty ice'' (CO:H/sub 2/O:CH/sub 3/OH:NH/sub 3/) and CO:NH/sub 3/ samples allow conclusive identification of the 2140 cm/sup -1/ and its associated ''wing'' feature (at 2135 cm/sup -1/) with solid CO, and CO complexed to other molecules. The broad 2165 cm/sup -1/ feature is due to one or more molecular species containing CequivalentN bonds. These species were formed in the laboratgory sample by ultraviolet photolysis of the frozen gas mixtures, a process that should also occur in grain mantles irradiated by ultraviolet light. The molecules containing the cyano groups have a much lower vapor pressure than pure frozen CO, and so can survive in considerably warmer environments. Toward W33A the column density of carbon in frozen molecules is comparable to that in the gas phase.

• Research Organization: Palomar Observatory, California Institute of Technology, now at University of California, Berkeley
• OSTI ID: 6719967
• Journal Information: Astrophys. J.; (United States), Journal Name: Astrophys. J.; (United States) Vol. 276:2; ISSN ASJOA
• Country of Publication: United States
• Language: English

Related Subjects

640105* -- Astrophysics & Cosmology-- Galaxies
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ABSORPTION SPECTRA
BASIC INTERACTIONS
CARBON COMPOUNDS
CARBON MONOXIDE
CARBON OXIDES
CHALCOGENIDES
ELECTROMAGNETIC INTERACTIONS
FUNCTIONS
INFRARED SPECTRA
INTERACTIONS
INTERSTELLAR GRAINS
OPACITY
OPTICAL PROPERTIES
OXIDES
OXYGEN COMPOUNDS
PARTICLE PRODUCTION
PARTICLES
PHOTOPRODUCTION
PHYSICAL PROPERTIES
PROTOSTARS
SPECTRA
SPECTRAL DENSITY
SPECTRAL FUNCTIONS
ULTRAVIOLET SPECTRA