Fullerenes in circumstellar and interstellar environments

Abstract

We recently identified several emission bands in the Spitzer-IRS spectrum of the unusual planetary nebula Tc 1 with the infrared active vibrational modes of the neutral fullerene species C60 and C70. Since then, the fullerene bands have been detected in a variety of sources representing circumstellar and interstellar environments. Abundance estimates suggest that C60 represents ~0.1%-1.5% of the available carbon in those sources. The observed relative band intensities in various sources are not fully compatible with single-photon heating and fluorescent cooling, and are better reproduced by a thermal distribution at least in some sources. The observational data suggests that fullerenes form in the circumstellar environments of evolved stars, and survive in the interstellar medium. Precisely how they form is still a matter of debate.

12 pages, 5 figures. To appear in the proceedings of IAU symposium 280 "The Molecular Universe"

References in corpus (7)

• Formation of buckminsterfullerene (C60) in interstellar space
• Formation of fullerenes in H-containing Planetary Nebulae
• On the Excitation and Formation of Circumstellar Fullerenes
• The formation of cosmic fullerenes from arophatic clusters
• Carbonaceous molecules in the oxygen-rich circumstellar environment of binary post-AGB stars: C_{60} fullerenes and polycyclic aromatic hydrocarbons
• Independent Emission and Absorption Abundances for Planetary Nebulae
• Identification of New Near-Infrared DIBs in the Orion Nebula

Cited by in corpus (6)

• Interstellar Fullerene Compounds and Diffuse Interstellar Bands
• On the Excitation and Formation of Circumstellar Fullerenes
• The formation of cosmic fullerenes from arophatic clusters
• Detection of Buckminsterfullerene emission in the diffuse interstellar medium
• The detection of C60 in the well-characterized planetary nebula M1-11
• Molecular studies of Planetary Nebulae