Issue |
A&A
Volume 682, February 2024
|
|
---|---|---|
Article Number | L18 | |
Number of page(s) | 7 | |
Section | Letters to the Editor | |
DOI | https://doi.org/10.1051/0004-6361/202349087 | |
Published online | 21 February 2024 |
Letter to the Editor
Hydrogenated amorphous carbon grains as an alternative carrier of the 9–13 μm plateau feature in the fullerene planetary nebula Tc 1
1
Instituto de Astrofísica de Canarias, 38205 La Laguna, Tenerife, Spain
e-mail: magm@iac.es; agarcia@iac.es
2
Departamento de Astrofísica, Universidad de La Laguna, 38206 La Laguna, Tenerife, Spain
3
Consejo Superior de Investigaciones Científicas (CSIC), 28006 Madrid, Spain
Received:
22
December
2023
Accepted:
5
February
2024
Fullerenes have been observed in several astronomical objects since the discovery of C60 in the mid-infrared (mid-IR) spectrum of the planetary nebula (PN) Tc 1. It has been suggested that the carriers of the broad unidentified infrared (UIR) plateau features, such as the 9–13 μm emission feature (12 μm hereafter), may be related to the formation of fullerenes. In particular, their carriers have been suggested to be mixed aromatic or aliphatic hydrocarbons such as hydrogenated amorphous carbon (HAC-like hereafter) grains. For this study, we modeled the mid-IR emission of the C60-PN Tc 1 with a photoionization code, including for the first time the laboratory optical constants (n and k indices) of HAC-like dust at 300 K. Interestingly, we find that the broad 12 μm plateau feature in Tc 1 is well reproduced by using a distribution of canonical HAC grains, while at the same time they provide an important fraction of the IR dust continuum emission and are consistent with the other UIR features observed (e.g., the broad 6–9 μm plateau feature). This finding suggests that HAC-like grains may be possible carriers of the 12 μm plateau feature, being likely related to the fullerene formation mechanism in PNe. More laboratory experiments, to obtain the optical constants of HAC-like dust with several structures or a composition at different physical conditions, are strongly encouraged – that is, in order to extend this pilot study to more fullerene PNe, and to unveil the details of fullerene formation and of the potential carriers of the elusive UIR plateau features.
Key words: astrochemistry / stars: AGB and post-AGB / planetary nebulae: individual: PN Tc 1
© The Authors 2024
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
This article is published in open access under the Subscribe to Open model. Subscribe to A&A to support open access publication.
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.