High-resolution optical spectroscopy of DY Cen: diffuse interstellar bands in a proto-fullerene circumstellar environment?

Abstract

We search high-resolution and high-quality VLT/UVES optical spectra of the hot R Coronae Borealis (RCB) star DY Cen for electronic transitions of the C60 molecule and diffuse interstellar bands (DIBs). We report the non-detection of the strongest C60 electronic transitions (e.g., those at ~3760, 3980, and 4024 A). Absence of C60 absorption bands may support recent laboratory results, which show that the ~7.0, 8.5, 17.4, and 18.8 um emission features seen in DY Cen - and other similar objects with PAH-like dominated IR spectra - are attributable to proto-fullerenes or fullerene precursors rather than to C60. DIBs towards DY Cen are normal for its reddening; the only exception is the DIB at 6284 A (possibly also the 7223A DIB) that is found to be unusually strong. We also report the detection of a new broad (FWHM~2 A) and unidentified feature centered at ~4000 A. We suggest that this new band may be related to the circumstellar proto-fullerenes seen at infrared wavelengths.

Accepted for publication in The Astrophysical Journal Letters (15 pages, 3 figures, and 2 tables)

References in corpus (3)

• A Catalog of Diffuse Interstellar Bands in the Spectrum of HD 204827
• Formation of fullerenes in H-containing Planetary Nebulae
• A search for diffuse bands in the circumstellar envelopes of post-AGB stars

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• Infrared Study of Fullerene Planetary Nebulae
• Interstellar Fullerene Compounds and Diffuse Interstellar Bands
• Infrared spectroscopy of fullerene C60/anthracene adducts
• Diffuse interstellar bands in fullerene planetary nebulae: the fullerenes - diffuse interstellar bands connection
• A search for diffuse bands in fullerene planetary nebulae: evidence of diffuse circumstellar bands
• C60 as a probe for astrophysical environments
• Dust around R Coronae Borealis stars: II. Infrared emission features in a H-poor environment
• GTC/CanariCam mid-IR imaging of the fullerene-rich Planetary Nebula IC 418: searching for the spatial distribution of fullerene-like molecules
• The changing nebula around the hot R Coronae Borealis star DY Centauri
• The C60:C60+ ratio in diffuse and translucent interstellar clouds
• The hot R Coronae Borealis star DY Centauri is a binary
• Diffuse interstellar bands in (proto-) fullerene-rich environments