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Aromatic, aliphatic, and the unidentified 21 micron emission features in proto-planetary nebulae

Published online by Cambridge University Press:  01 February 2008

Bruce J. Hrivnak ,
Kevin Volk ,
T. R. Geballe  and
Sun Kwok
Bruce J. Hrivnak
Affiliation:
Department of Physics & Astronomy, Valparaiso University, Valparaiso IN, 46383, USA email: [email protected]
Kevin Volk
Affiliation:
Gemini Observatory, 670 North A'ohoku Place, Hilo, HI 96720, USA email: [email protected], [email protected]
T. R. Geballe
Affiliation:
Gemini Observatory, 670 North A'ohoku Place, Hilo, HI 96720, USA email: [email protected], [email protected]
Sun Kwok
Affiliation:
Department of Physics, University of Hong Kong, Hong Kong, China email: [email protected]
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Abstract

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Aromatic features at 3.3, 6.2, 7.7, 8.6, 11.3 μm are observed in proto-planetary nebulae (PPNe) as well as in PNe and H ii regions. Aliphatic features at 3.4 and 6.9 μm are also observed; however, these features are often stronger in PPNe than in PNe. These observations suggest an evolution in the features from simple molecules (C2H2) in AGB stars to aliphatics in PPNe to aromatics in PNe. In the same carbon-rich PPNe, a strong, broad, unidentified 21 μm emission feature has been found. We will present recent observations of the aromatic, aliphatic, and 21 μm emission features, along with C2H2 (13.7 μm) and a new feature at 15.8 μm, and discuss correlations among them and other properties of these PPNe.

Keywords

Astrochemistrycircumstellar matterISM: lines and bandsinfrared: ISMstars: AGB and post-AGBplanetary nebulae: general
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 4 , Symposium S251: Organic Matter in Space , February 2008 , pp. 213 - 214
Copyright
Copyright © International Astronomical Union 2008

References

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