Bibcode
Díaz-Luis, J. J.; García-Hernández, D. A.; Manchado, A.; García-Lario, P.; Villaver, E.; García-Segura, G.
Bibliographical reference
The Astronomical Journal, Volume 155, Issue 3, article id. 105, 11 pp. (2018).
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3
2018
Citations
9
Refereed citations
9
Description
We present seeing-limited narrow-band mid-IR GTC/CanariCam images of the
spatially extended fullerene-containing planetary nebula (PN) IC 418.
The narrow-band images cover the C60 fullerene band at 17.4
μm, the polycyclic aromatic hydrocarbon like (PAH-like) feature at
11.3 μm, the broad 9–13 μm feature, and their adjacent
continua at 9.8 and 20.5 μm. We study the relative spatial
distribution of these complex species, all detected in the Spitzer and
Infrared Space Observatory spectra of IC 418, with the aim of getting
observational constraints to the formation process of fullerenes in
H-rich circumstellar environments. A similar ring-like extended
structure is seen in all narrow-band filters, except in the dust
continuum emission at 9.8 μm, which peaks closer to the central star.
The continuum-subtracted images display a clear ring-like extended
structure for the carrier of the broad 9–13 μm emission, while
the spatial distribution of the (PAH-like) 11.3 μm emission is not so
well defined. Interestingly, a residual C60 17.4 μm
emission (at about 4σ from the sky background) is seen when
subtracting the dust continuum emission at 20.5 μm. This residual
C60 emission, if real, might have several interpretations,
the most exciting being perhaps that other fullerene-based species like
hydrogenated fullerenes with very low H-content may contribute to the
observed 17.4 μm emission. We conclude that higher sensitivity mid-IR
images and spatially resolved spectroscopic observations (especially in
the Q-band) are necessary to get some clues about fullerene formation in
PNe.
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