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CN and HCN in the infrared spectrum of IRC + 10216The abundance of HCN in the inner circumstellar shell of IRC + 10216 has been remeasured using the 12-micron nu2 band. The 12-micron lines are less saturated than HCN 3-micron lines previously detected in the spectrum of IRC + 10216. The observed 12-micron HCN line is formed in the circumstellar shell from about 4 to 12 R sub * in accord with a photospheric origin for HCN. The derived HCN abundance in the 4 to 12 R sub* region is 4 x 10 exp-5 and the column density is 7 x 10 exp 18/sq cm. The 5-micron CN vibration-rotation fundamental band was detected for the first time in an astronomical source. Using four CN lines, the CN column density was determined to be 2.6 x 10 exp 15/sq cm and the rotational temperature to be 8 +/-2 K. The peal radial abundance is 1 x 10 exp -5. The values for the temperature and abundance are in good agreement with microwave results and with the formation of CN from the photolysis of HCN.
Document ID
Document Type
Reprint (Version printed in journal)
External Source(s)
Wiedemann, G. R. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Deming, D. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Jennings, D. E. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Hinkle, Kenneth H. (Kitt Peak National Observatory Tucson, AZ, United States)
Keady, John J. (Los Alamos National Laboratory NM, United States)
Date Acquired
August 15, 2013
Publication Date
November 20, 1991
Publication Information
Publication: Astrophysical Journal, Part 1
Volume: 382
ISSN: 0004-637X
Subject Category
Distribution Limits