Non-detection of the 1.67 micron band in HB 5? Implications for PAH-related models

Bibcode
1992A&A...263..281M
Magazzu, A.; Strazzulla, G.
Bibliographical reference

Astronomy and Astrophysics (ISSN 0004-6361), vol. 263, no. 1-2, p. 281-284.

Advertised on:
9
1992
Number of authors
2
IAC number of authors
1
Citations
8
Refereed citations
8
Description
In this paper we present a high resolution IR spectrum of the planetary nebula Hb5, over the range 1.6-1.75 micron. Our aim is to test the hypothesis invoking emission from upper vibrational levels in excited PAH molecules and anharmonicity of the C-H stretching mode to explain the weak features observed in the 3 micron range. The predicted first harmonic of the 3.3 micron band at 1.67 micron has not been detected. The upper limit we set indicates that his band must be at least 45 times weaker than the 3.4 micron feature. This, together with the high value of the F(3.4)/F(3.3) ratio, challenges the assumption that the 3.4 micron band is the first hot band.
Type
Refereed
Planetary nebulae
Astronomical models
Interstellar extinction

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