A search for H3 molecules in the planetary nebula NGC 7027
Date
1987
Authors
Gussie, Grant Trevor
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Abstract
Spectrophotometric observations near A= 7100 A have been made of the young planetary nebula NGC7027. The spectra were obtained with the 1. 83 m telescope at the Dominion Astrophysical Observatory. The observations were made in an attempt to confirm the tentative identification by Pritchet and Grillmair (1984) of a weak emission line at A= 5624 A as triatomic hydrogen emission.
None of the newly discovered spectral features have the structure expected of H3 molecular emission. The previous identification of the 5624A feature is therefore challenged. Theoretical chemical models are discussed, with emphasis on the production of H3 in the planetary nebula's transition zone and the surrounding molecular envelope. It is found that H3 is produced very inefficiently in these regions. The theory of H3 molecular spectroscopy is reviewed. Those spectral features that may be observed optically are emphasized.
Also reviewed are procedures for the computer reduction of digitally recorded spectral observations. More specifically, the use of the spectrophotometric reduction package RETICENT is discussed.