13 C Isotopic Ratios Of HC3N On Titan Measured With ALMA

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HC3N

We present the first determination of the abundance ratios of 13C substitutions of cyanoacetylene (HC3N), [H13CCCN]:[HC13CCN]:[HCC13CN] in Titan's atmosphere measured using millimeter-wave spectra obtained by the Atacama Large Millimeter-submillimeter Array.

To compare the line intensities precisely, datasets which include multiple molecular lines were extracted to suppress effects of Titan's environmental conditions and observation settings. The [HC13CCN]:[HCC13CN] and [H13CCCN]:[HCC13CN}] ratios were obtained from 12 and 1 selected datasets, respectively. As a result, nearly the uniform [H13CCCN]:[HC13CCN]:[HCC13CN] abundance ratios as 1.17 (±0.20) : 1.09 (±0.25) : 1 (1σ) were derived, whereas previously reported ratios for interstellar medium (ISM) have shown large anomalies that may be caused by 13C concentrations in precursors. The result obtained here suggests that 13C concentration processes suggested in the ISM studies do not work effectively on precursors of HC3N and HC3N itself due to Titan's high atmospheric temperature and/or depletion of both 13C and 13C+.

Takahiro Iino, Kotomi Taniguchi, Hideo Sagawa, Takashi Tsukagoshi

Comments: Accepted for publication in the Planetary Science Journal
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)
Cite as: arXiv:2108.05019 [astro-ph.EP] (or arXiv:2108.05019v1 [astro-ph.EP] for this version)
Submission history
From: Takahiro Iino
[v1] Wed, 11 Aug 2021 04:05:11 UTC (2,645 KB)
https://arxiv.org/abs/2108.05019
Astrobiology, Astrochemistry,

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