CN abundance variations in the shell of IRC +10216

Journal Article · Tue Jun 01 04:00:00 EDT 1982 · Astrophys. J.; (United States)

DOI:https://doi.org/10.1086/159973· OSTI ID:6806067

Wootten, A; Lichten, S M; Sahai, R; Wannier, P G

First observations of the N = 2-1 line of CN at 226.9 GHz are reported. High-resolution maps of IRC+10216 and OMC-1 show that the peak in both sources is compact but resolved in our 30'' beam. In IRC+10216 the emission extends approx.70'' at the line center velocity. A model for CN excitation and the absence of infrared vibration--rotation absorption lines suggest the presence of a source of CN molecules in the outer circumstellar shell. Examination of chemical, expansion, and photodissociation time scales in the outer shell leads to the identification of HCN photodissociation by the interstellar radiation field as a plausible source. This model explains the large discrepancy in the CN abundance predicted by chemical equilibrium models of the shell and confirms the importance of photodissociation in the chemistry of circumstellar shells. Maps and spectra were also made in OMC-1 and OMC-2. In OMC-1, CN emission lies along a narrow ridge, peaking in the BN/KL region.

• Research Organization: Owens Valley Radio Obervatory, California Institute of Technology
• OSTI ID: 6806067
• Journal Information: Astrophys. J.; (United States), Journal Name: Astrophys. J.; (United States) Vol. 257:1; ISSN ASJOA
• Country of Publication: United States
• Language: English

Related Subjects

640105* -- Astrophysics & Cosmology-- Galaxies
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ABUNDANCE
CARBON STARS
CHEMISTRY
COSMIC DUST
COSMIC GASES
CYANIDES
DISSOCIATION
DUSTS
FLUIDS
FREQUENCY RANGE
GASES
GHZ RANGE
GHZ RANGE 01-100
HYDROCYANIC ACID
HYDROGEN COMPOUNDS
INFRARED SPECTRA
INORGANIC ACIDS
MAIN SEQUENCE STARS
MICROWAVE SPECTRA
PHOTOCHEMISTRY
SPECTRA
STARS