A Spitzer/IRS spectral study of a sample of galactic carbon-rich proto-planetary nebulae

Abstract

Recent infrared spectroscopic observations have shown that proto-planetary nebulae (PPNs) are sites of active synthesis of organic compounds in the late stages of stellar evolution. This paper presents a study of Spitzer/IRS spectra for a sample of carbon-rich PPNs, all except one of which show the unidentified 21 micron emission feature. The strengths of the aromatic infrared band (AIB), 21 micron, and 30 micron features are obtained by decomposition of the spectra. The observed variations in the strengths and peak wavelengths of the features support the model that the newly synthesized organic compounds gradually change from aliphatic to aromatic characteristics as stars evolve from PPNs to planetary nebulae.

32 pages, 11 figures, accepted for publication in ApJ

References in corpus (4)

• The unusual hydrocarbon emission from the early carbon star HD 100764: The connection between aromatics and aliphatics
• Detection of C60 in the proto-planetary nebula IRAS 01005+7910
• A Spitzer IRS Spectral Atlas of Luminous 8 micron Sources in the Large Magellanic Cloud
• The Sulfur Abundance Anomaly in Planetary Nebulae

Cited by in corpus (17)

• Detection of C60 in the proto-planetary nebula IRAS 01005+7910
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• The Mystery of Unidentified Infrared Emission Bands
• The 11.2 $\mu$m emission of PAHs in astrophysical objects
• On the Aliphatic versus Aromatic Content of the Carriers of the "Unidentified" Infrared Emission Features
• Search for Hydrogenated C${}_{60}$ (fulleranes) in Circumstellar Envelopes
• High-resolution optical spectroscopy of DY Cen: diffuse interstellar bands in a proto-fullerene circumstellar environment?
• Candidate carriers and synthetic spectra of the 21- and 30-mu protoplanetary nebular bands
• A Tale of Three Mysterious Spectral Features in Carbon-Rich Evolved Stars: The 21 Micrometer, 30 Micrometer, and "Unidentified Infrared" Emission Features
• On the carbonaceous carriers of IR plateau and continuum emission
• Chemical Abundances in the PN Wray16-423 in the Sagittarius Dwarf Spheroidal Galaxy: Constraining the Dust Composition
• 30-micron sources in galaxies with different metallicities
• Are fulleranes responsible for the 21 micron feature?
• Excitation of Unidentified Infrared Bands by H atom impact
• An Infrared Photometric and Spectroscopic Study of Post-AGB Stars
• Dust at sub-solar metallicity: the case of post-AGB stars in the Large Magellanic Cloud