Carbon chain diversity in L1544 and IRAS 16293–2422: an astrochemical pathfinder study for the SKAO
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staf1941.pdf
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Published version
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3.25 MB
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Checksum (MD5)
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Author(s)
Giani, Lisa
Bianchi, Eleonora
Remijan, Anthony
Codella, Claudio
Sabatini, Giovanni
Podio, Linda
Ceccarelli, Cecilia
De Simone, Marta
Balucani, Nadia
Caselli, Paola
Date Issued
November 6, 2025
Journal
Monthly Notices of the Royal Astronomical Society
Publisher
Oxford University Press
Citation
Lisa Giani, Eleonora Bianchi, Anthony Remijan, Claudio Codella, Giovanni Sabatini, Linda Podio, Cecilia Ceccarelli, Marta De Simone, Nadia Balucani, Paola Caselli, Eric Herbst, Francois Lique, Silvia Spezzano, Charlotte Vastel, Brett McGuire, Carbon chain diversity in L1544 and IRAS 16293–2422: an astrochemical pathfinder study for the SKAO, Monthly Notices of the Royal Astronomical Society, Volume 544, Issue 4, December 2025, Pages 4043–4061.
Version
Final published version
Abstract
Astrochemical observations have revealed a surprisingly high level of chemical complexity, including long carbon chains, in the earliest stages of Sun-like star formation. The origin of these species and whether they undergo further growth, possibly contributing to the molecular complexity of planetary systems, remain open questions. We present recent observations performed using the 100-m Green Bank Telescope of the prestellar core L1544, and the protostellar system IRAS 16293–2422. In L1544, we detected several complex carbon-bearing species, including C2_S, C3_S, C3_N, c-C3_H, C4_H, and C6_H, complementing previously reported emission of cyanopolyynes. In IRAS 16293–2422, we detected c-C3_H and, for the first time, HC7_N. Thanks to the high spectral resolution, we refine the rest frequencies of several c-C3_H and C6_H transitions. We perform radiative transfer analysis, highlighting a chemical difference between the two sources: IRAS 16293–2422 shows column densities 10 to 100 times lower than L1544. We perform astrochemical modelling, employing an up-to-date chemical network with revised reaction rates. Models reproduce the general trends, with cyanopolyyne and polyynyl radical abundances decreasing as molecular size increases, but underestimate the abundances of cyanopolyynes longer than HC5_N by up to two orders of magnitude. Current models, which include the dominant neutral–neutral formation routes, cannot account for this discrepancy, suggesting that the chemical network is incomplete. We propose that additional ion–molecule reactions are crucial for the formation of these species. Developing a more comprehensive chemical network for long carbon chains is essential for accurately interpreting present and future observations.
MIT Department
Massachusetts Institute of Technology. Department of Chemistry
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DOI of Published Version
https://doi.org/10.1093/mnras/staf1941
