Siebert, MA, Van de Sande, M orcid.org/0000-0001-9298-6265, Millar, TJ et al. (1 more author) (2022) Investigating Anomalous Photochemistry in the Inner Wind of IRC+10216 through Interferometric Observations of HC3N. Astrophysical Journal, 941 (1). 90. ISSN 0004-637X
Abstract
In recent years, many questions have arisen regarding the chemistry of photochemical products in the carbon-rich winds of evolved stars. To address them, it is imperative to constrain the distributions of such species through high-angular-resolution interferometric observations covering multiple rotational transitions. We used archival Atacama Large Millimeter/submillimeter Array observations to map rotational lines involving high energy levels of cyanoacetylene (HC3N) toward the inner envelope (radius < 8''/1000 au) of the carbon star IRC+10216. The observed lines include the J = 28 − 27, J = 30 − 29, and J = 38 − 37 transitions of HC3N in its ground vibrational state. In contrast to previous observations of linear carbon chains toward this asymptotic giant branch (AGB) star that show extended, hollow emission at 15''–20'' radii (e.g., C4H, C6H, and HC5N), the maps of the HC3N lines here show compact morphologies comprising various arcs and density enhancements, with significant emission from gas clumps at an angular distance of ∼3'' (350 au) from the central AGB star. We compared visibility sampled non-LTE radiative transfer models with the observed brightness distributions, and derive a fractional abundance with respect to H2 of 10−8 for HC3N at the radii probed by these lines. These results are consistent with enhanced photochemistry occurring in warm (∼200 K) regions of the circumstellar envelope. After application of a specialized chemical model for IRC+10216, we find evidence that the enhanced HC3N abundances in the inner wind are most likely due to a solar-type binary companion initiating photochemistry in this region.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2022. The Author(s). This is an open access article under the terms of the Creative Commons Attribution License (CC-BY 4.0), which permits unrestricted use, distribution and reproduction in any medium, provided the original work is properly cited. |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Engineering & Physical Sciences (Leeds) > School of Physics and Astronomy (Leeds) > Astrophysics (Leeds) |
Depositing User: | Symplectic Publications |
Date Deposited: | 08 Nov 2022 15:51 |
Last Modified: | 30 Aug 2023 15:07 |
Status: | Published |
Publisher: | IOP Publishing |
Identification Number: | 10.3847/1538-4357/ac9e52 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:192959 |