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REVIEW 3 major objections 3 minor 36 references

$^{13}$C Isotopic Fractionation of CCH in Two Starless Cores: L1521B and L134N

T0 review · 3 major / 3 minor · reviewed 2026-08-14 · deepseek-v4-flash

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Pith's one-line read In the starless cores L1521B and L134N, C$^{13}$CH is more abundant than $^{13}$CCH, implying that the two carbon positions of CCH are not formed or exchanged symmetrically in cold dark clouds.

desk verdict New but modest CCH isotopologue measurements in two starless cores; the asymmetry claim is plausible but the new data alone only marginally exclude unity. read the letter →

arxiv 1908.09983 v1 pith:XORTCBAS submitted 2019-08-27 astro-ph.GA astro-ph.SR

Kotomi Taniguchi , Eric Herbst , Hiroyuki Ozeki , Masao Saito This is my paper · ORCID
classification astro-ph.GAastro-ph.SR
keywords CCH13Cisotopologuesisotopicfractionationstarlesscoresastrochemistryethynylradicaldarkcloudscarbonisotoperatio
verification ladder T0 review T1 audit T2 compute T3 formal

The pith

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The reading

This paper reports observations of the ethynyl radical CCH and its two singly substituted carbon-13 versions, $^{13}$CCH and C$^{13}$CH, toward two cold, starless cores. The authors find that C$^{13}$CH is detectable while $^{13}$CCH is not, placing lower limits of $>1.1$ and $>1.4$ on the column density ratio $N(\mathrm{C^{13}CH})/N(^{13}\mathrm{CCH})$. Because the two carbon atoms occupy different positions in the molecule, this imbalance shows that the chemistry forming or reprocessing CCH does not treat the two sites symmetrically. The result strengthens the case that this asymmetry is common in dark clouds and connects to the larger puzzle of why carbon-chain molecules show high $^{12}$C/$^{13}$C ratios.

What carries the argument

The central objects are the two singly substituted $^{13}$C isotopologues of the ethynyl radical, $^{13}$CCH (with $^{13}$C at the end carbon) and C$^{13}$CH (with $^{13}$C at the central carbon), observed in the $N=1-0$ rotational transition. The ratio of their column densities is the key observable. The paper invokes two mechanisms that could create the imbalance: the formation reaction CH$_2$ + C $\rightarrow$ C$_2$H + H, whose two carbon atoms are not equivalent and which dominates CCH formation after $10^3$ years, and the isotopomer-exchange reaction $^{13}$CCH + H $\rightarrow$ C$^{13}$CH + H, exothermic by 8.1 K, which converts the less abundant form to the more abundant one. To explain the high $^{12}$C/$^{13}$C ratio in CCH, the paper highlights a cycle in which CCH is destroyed by C$^+$ to form C$_3^+$, which then reforms CCH; because $^{13}$C$^+$ is depleted by reaction with CO, this cycle raises the $^{12}$C/$^{13}$C ratio and is efficient only before about $10^3$ years.

What would settle it

A measurement that detects $^{13}$CCH at a level putting $N(\mathrm{C^{13}CH})/N(^{13}\mathrm{CCH})$ below unity in a similar cloud, or a direct determination of the excitation temperatures of the two isotopologues showing they differ substantially from the assumed 6.5 K, would falsify the paper's conclusion.

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Extended reading notes

Core claim

The central claim is that in the starless cores L1521B and L134N the isotopologue C$^{13}$CH is more abundant than $^{13}$CCH, with column density ratios $N(\mathrm{C^{13}CH})/N(^{13}\mathrm{CCH})$ greater than $>1.1$ and $>1.4$ respectively, where C$^{13}$CH is detected at signal-to-noise ratio ~4 and $^{13}$CCH remains undetected. The authors argue this asymmetry reflects a genuine $^{13}$C isotopic fractionation between the two carbon positions, and that it is probably a general property of dark clouds, consistent with earlier observations in TMC-1 and L1527. They also derive high $^{12}$C/$^{13}$C ratios for CCH compared with HC$_3$N, especially in the younger cores, and propose that a reaction cycle involving C$^+$ and small hydrocarbon ions can raise the $^{12}$C/$^{13}$C ratio of CCH specifically during the early stages of cloud evolution.

Load-bearing premise

The derived column densities assume the rare isotopologues are in local thermodynamic equilibrium with excitation temperatures equal to those of the normal species; if those temperatures differ, the ratio lower limits and the inferred $^{12}$C/$^{13}$C ratios could change.

Editorial extensions

If this is right

  • The lower limits imply that the two carbon positions in CCH are populated asymmetrically in cold cores, so formation or exchange chemistry preserves a positional bias.
  • If the pattern is common, then CCH isotopologue ratios can be used alongside HC$_3$N ratios to trace carbon fractionation and cloud age.
  • The proposed C$^+$ cycle predicts that young, C$^+$-rich cores should show the highest $^{12}$C/$^{13}$C ratios in CCH, and that the ratio should drop as the core evolves.
  • The comparison with HC$_3$N suggests that the fractionation pattern differs between molecules built from C$_2$H$_2$ and those built from CCH, offering a diagnostic of formation pathways.

Reading between the lines

Editorial extensions of the paper, not claims the author makes directly.

  • A testable extension is to map the C$^{13}$CH/$^{13}$CCH ratio across a single cloud; if the C$^+$ cycle drives the effect, the ratio should peak in the outer, less shielded regions where C$^+$ survives.
  • If selective photodissociation, which the authors note could matter, is important, then the ratio should vary with optical depth and position within the cloud, which a position-switched observation could check.
  • The asymmetry might also carry over to other small carbon chains built from CCH, such as C$_3$H or HC$_3$N; measuring their position-specific $^{13}$C ratios could reveal whether the bias is inherited or re-established by later reactions.
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Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, and a circularity audit.

Referee Report

3 major / 3 minor

Summary. The paper presents Nobeyama 45 m observations of the N = 1-0 lines of CCH and its two 13C isotopologues, 13CCH and C13CH, toward the starless cores L1521B and L134N. C13CH is detected in both sources, while 13CCH is not detected, leading to lower limits on N(C13CH)/N(13CCH) of >1.1 and >1.4, respectively. Column densities of the normal species are derived with RADEX, and those of the isotopologues with LTE and an assumed excitation temperature equal to the normal species. The 12C/13C ratios of CCH are compared with those of HC3N, and the Nautilus astrochemical model is used to discuss formation and destruction pathways that could produce the observed isotope dilution. The paper concludes that C13CH tends to be more abundant than 13CCH in dark clouds and that reactions of hydrocarbons with C+ can explain the high 12C/13C ratios of CCH.

Significance. The dataset is valuable because it extends 13C isotopologue studies of CCH to two additional starless cores and uses simultaneous observations that minimize calibration uncertainties. The paper is transparent about non-detections and provides line parameters, column densities, and model specifications in a reproducible way. If the isotopologue asymmetry and the proposed C+/hydrocarbon mechanism are correct, they would place useful constraints on carbon-chain formation chemistry. However, the new observations alone do not firmly establish the central asymmetry claim: the ratios are lower limits whose uncertainties overlap with unity, and the case relies substantially on earlier TMC-1 and L1527 results. The chemical discussion is a plausible hypothesis rather than a conclusive test of the mechanism.

major comments (3)
  1. [Section 3.2/Table 2/footnote 5] The claim that C13CH is more abundant than 13CCH in L1521B and L134N is not supported by the quoted uncertainties. The ratio lower limit in L1521B is >1.1 with a 1σ error of 0.3, so the 1σ lower bound is 0.8, which is consistent with equal abundances. In L134N the limit is >1.4±0.3, giving a 1σ lower bound of 1.1, but the C13CH line used there (J=3/2-1/2, F1=2-1, F=3/2-1/2) has an integrated intensity of 0.009±0.004 K km s−1, i.e. S/N≈2.3. Before asserting an asymmetry, the paper should present a statistical test that combines the measured C13CH column density with the 3σ upper limit on 13CCH (for example, a posterior probability that the ratio exceeds unity). If such a test cannot exclude equality at 1–2σ, the abstract and conclusions should be reworded to say that the new data are consistent with the asymmetry seen in TMC-1 and L1527 rather than that the asymmetry is detected in these two cores.
  2. [Section 3.2] The C13CH column density in each source is derived from a single hyperfine component (F=5/2-3/2 in L1521B and F=3/2-1/2 in L134N), and the two sources use different components. In L1521B, a second component is reported as tentatively detected (S/N=3), which could provide a consistency check; in L134N both reported detections have low integrated S/N. The authors should quantify the systematic uncertainty arising from the choice of line and from possible departures from LTE, especially because the adopted excitation temperatures (6.4–6.6 K) are derived for the normal species and are well below the assumed kinetic temperature of 10 K.
  3. [Section 4.1 and Conclusions] The statement that 'the characteristic that 13CCH is less abundant than C13CH is likely common for dark clouds' extrapolates beyond the data. In the two new sources the asymmetry is only a lower limit, and in L1521B the 1σ range includes unity. Although earlier observations in TMC-1 and L1527 reported ratios of 1.6±0.4 and 1.6±0.1 (3σ), the new data are not an independent confirmation. The authors should either perform a combined significance analysis or qualify the conclusion as 'consistent with the previously suggested common asymmetry' rather than asserting it as a direct inference from the new observations.
minor comments (3)
  1. [Abstract] The phrase 'detected C13CH with a signal-to-noise (S/N) ratio of 4' is ambiguous. In Table 1, the integrated S/N of the C13CH line used for the column density is about 12 in L1521B but only about 2.3 in L134N; please specify which S/N metric is quoted and use the same metric for both sources.
  2. [Section 4.2.2] The sentence 'CCH seems to be optically thick because the optical thickness of the weakest hyperfine components are around 0.2' is internally inconsistent: an optical depth of 0.2 is optically thin, not thick. Please correct this wording.
  3. [Throughout] The paper uses 'isotopologues' and 'isotopomers' interchangeably. For the two 13C-bearing variants of CCH, 'isotopomers' is the more precise term because the molecules have the same atomic composition but differ in the position of the isotope; please make the terminology consistent.

Circularity Check

0 steps flagged · score 0.0 of 10

No significant circularity: the C13CH/13CCH ratio is measured from independent spectra, and the chemical model interprets rather than fits the observations.

full rationale

This paper's central observational claim (C13CH more abundant than 13CCH in L1521B and L134N) is derived directly from independent spectral measurements: C13CH lines are detected at S/N~4 while 13CCH lines are not, and the column-density lower limits follow from the observed intensities and 3σ upper limits. The LTE assumption that the isotopologue excitation temperatures equal those of the normal species is an interpretative assumption, not a fitted parameter reused as a prediction, and the ratio is not forced by definition. The chemical modeling (Nautilus with KIDA network) is used to interpret the measured ratios, not to fit them; the model does not take the observed N(C13CH)/N(13CCH) ratio as an input. The self-citations (Taniguchi et al. 2016a, 2017) provide prior observations of other molecules and a standard column-density formula; they are not load-bearing because the present isotopologue detection and non-detection stand on the new Nobeyama data. No equation in the paper reduces to its inputs: the claimed ratio is an observed quantity, and the proposed mechanisms (reaction 8, isotopomer exchange) are discussed as possible explanations rather than derived from the data by construction. Statistical and excitation-temperature caveats are uncertainties, not circularity. Therefore no significant circularity is found.

Assumptions & free parameters 6 free parameters · 6 assumptions · 0 invented entities

The observational ratio is grounded in standard radiative transfer; its main assumption is LTE/equal excitation for isotopologues. The chemical interpretation additionally uses a large public network and several typical dark-cloud parameters. No new entities are introduced.

free parameters (6)
  • H2 number density for RADEX analysis = 1e5 cm-3 (adopted); alternatives 5e4, 2.1e4 cm-3
    The normal-species column density and excitation temperature depend on the assumed H2 density. The authors adopt 1e5 cm-3 as typical for dark clouds and list alternative values. The isotopologue ratio is less sensitive because both isotopologues share the assumed excitation temperature.
  • Gas kinetic temperature = 10 K
    Assumed for both RADEX and Nautilus as a typical dark-cloud value. Affects the non-LTE excitation calculation and the chemical model output.
  • Excitation temperature of 13C isotopologues = 6.6 K (L1521B), 6.4 K (L134N), set equal to normal CCH
    LTE column densities of 13CCH and C13CH are computed with this assumed equality. If the isotopologues are sub-thermally excited differently from CCH, the ratio lower limits change.
  • Cosmic-ray ionization rate = 1.3e-17 s-1
    Input to the Nautilus model; a standard dark-cloud value. Affects the modeled C+ abundance and the proposed cycle.
  • Visual extinction = 10 mag
    Input to the Nautilus model; controls photodissociation shielding. This is where selective photodissociation is excluded.
  • Model density = 2e4 cm-3
    Fixed density for the Nautilus run, stated as typical for dark clouds. Combined with T=10 K, affects the chemical evolution.
assumptions (6)
  • standard math Standard radiative transfer equations for optical depth and column density (Eqs. 2-4).
    Used for LTE column densities of isotopologues and is a standard, unstated-in-proof background result.
  • domain assumption LTE and equal excitation temperatures for the 13C isotopologues.
    Assumed in Section 3.2; not independently verified against multi-line data.
  • domain assumption RADEX collision rates from Spielfiedel et al. (2012).
    Non-LTE code relies on these rates; uncertainties affect excitation temperature.
  • domain assumption Chemical network from KIDA and grain-surface sources is complete enough.
    The proposed C+ cycle is only meaningful if the network captures the major formation and destruction paths of CCH.
  • domain assumption Initial elemental abundances from Acharyya & Herbst (2017).
    Model evolution starts from these abundances; they set the carbon budget.
  • domain assumption Reaction (1) and isotopomer exchange rates from Furuya et al. (2011).
    The discussion of dilution and exchange relies on these prior rates and energies.

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Cite this review

Pith. "Pith review of $^{13}$C Isotopic Fractionation of CCH in Two Starless Cores: L1521B and L134N." pith.science (2026). https://pith.science/paper/XORTCBAS

@misc{pith2026190809983,
  author       = {Pith},
  title        = {Pith review of: $^13$C Isotopic Fractionation of CCH in Two Starless Cores: L1521B and L134N},
  year         = {2026},
  howpublished = {\url{https://pith.science/paper/XORTCBAS}},
  note         = {Machine review of arXiv:1908.09983}
}
abstract

We have carried out observations of CCH and its two $^{13}$C isotopologues, $^{13}$CCH and C$^{13}$CH, in the 84 - 88 GHz band toward two starless cores, L1521B and L134N (L183), using the Nobeyama 45 m radio telescope. We have detected C$^{13}$CH with a signal-to-noise (S/N) ratio of 4, whereas no line of $^{13}$CCH was detected in either the dark clouds. The column densities of the normal species were derived to be ($1.66 \pm 0.18$)$\times 10^{14}$ cm$^{-2}$ and ($7.3 \pm 0.9$)$\times 10^{13}$ cm$^{-2}$ ($1 \sigma$) in L1521B and L134N, respectively. The column density ratios of $N$(C$^{13}$CH)/$N$($^{13}$CCH) were calculated to be $>1.1$ and $>1.4$ in L1521B and L134N, respectively. The characteristic that $^{13}$CCH is less abundant than C$^{13}$CH is likely common for dark clouds. Moreover, we find that the $^{12}$C/$^{13}$C ratios of CCH are much higher than those of HC$_{3}$N in L1521B by more than a factor of 2, as well as in Taurus Molecular Cloud-1 (TMC-1). In L134N, the differences in the $^{12}$C/$^{13}$C ratios between CCH and HC$_{3}$N seem to be smaller than those in L1521B and TMC-1. We discuss the origins of the $^{13}$C isotopic fractionation of CCH and investigate possible routes that cause the significantly high $^{12}$C/$^{13}$C ratio of CCH especially in young dark clouds, with the help of chemical simulations. The high $^{12}$C/$^{13}$C ratios of CCH seem to be caused by reactions between hydrocarbons (e.g., CCH, C$_{2}$H$_{2}$, $l,c$-C$_{3}$H) and C$^{+}$.

Figures

Figures reproduced from arXiv: 1908.09983 by the authors.

Figure 1
Figure 1. Spectra of the N = 1 − 0 transition lines of CCH in L1521B and L134N. The vertical lines indicate the systemic velocities of each source (6.5 km s−1 and 2.5 km s−1 for L1521B and L134N, respectively). The red curves show the results of the best Gaussian fit [PITH_FULL_IMAGE:figures/full_fig_p006_1.png] view at source ↗
Figure 2
Figure 2. Spectra of the N = 1 − 0 transition lines of 13CCH and C13CH in L1521B. The vertical lines indicate the systemic velocity (6.5 km s−1 ). The red curves show the results of the best Gaussian fit. In this section, we compare the column densities between the two 13C isotopologues of CCH, namely the fractionation between the two 13C isotopomers, in the observed two starless cores. Because we could not detect 13CCH with … view at source ↗
Figure 3
Figure 3. Spectra of the N = 1 − 0 transition lines of 13CCH and C13CH in L134N. The vertical lines indicate the systemic velocity (2.5 km s−1 ). The red curves show the results of the best Gaussian fit. Among the above three reactions, only reaction (8) is able to cause the 13C isotopic fractionation in CCH, because the two carbon atoms are not clearly equivalent. Hence, Sakai et al. (2010) deduced that the observed differen… view at source ↗
Figures from the paper (3 more)
Figure 4
Figure 4. Figure 4: Results of the model calculation. Upper panel; the time dependence of the CCH abundance respect to total hydrogen (red line). The blue and green lines indicate the observed abundances in L1521B and L134N, respectively. Middle panel; the time dependence of the C (red), …
Figure 5
Figure 5. Figure 5: Comparisons of the 12C/13C ratios of CCH and HC3N in the three starless cores; L1521B, L134N, and TMC-1. The errors indicate the standard deviation. The yellow range (12C/13C= 60 − 70) shows the values in the local interstellar medium. The values are the same as [PITH…
Figure 6
Figure 6. Figure 6: Reaction schemes of small hydrocarbons. A red triangle highlights the reaction cycle that causes the high 12C/13C ratios in CCH and is efficient especially in the early stage (t < 103 yr). After t = 103 yr, the abundance of ionic carbon (C+) rapidly decreases (see the …

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Works this paper leans on

36 extracted references · 28 canonical work pages

  1. [1]

    2017, ApJ, 850, 105

    Acharyya, K., & Herbst, E. 2017, ApJ, 850, 105

    work page 2017

  2. [2]

    J., & Kaiser, R

    Bergantini, A., G´ obi, S., Abplanalp, M. J., & Kaiser, R. I. 2018, ApJ, 852, 70

    work page 2018

  3. [3]

    M., Herbst, E., Kalenskii, S

    Burkhardt, A. M., Herbst, E., Kalenskii, S. V., et al. 2018, MNRAS, 474, 5068

    work page 2018

  4. [4]

    E., Irvine, W

    Dickens, J. E., Irvine, W. M., Snell, R. L., et al. 2000, ApJ, 542, 870

    work page 2000

  5. [5]

    1997, ApJ, 489, 113

    Fukuzawa, K., & Osamura, Y. 1997, ApJ, 489, 113

    work page 1997

  6. [6]

    2011, ApJ, 731, 38

    Furuya, K., Aikawa, Y., Sakai, N., & Yamamoto, S. 2011, ApJ, 731, 38

    work page 2011

  7. [7]

    Garrod, R. T. 2013, ApJ, 765, 60

    2013

  8. [8]

    E., Herbst, E., & Garrod, R

    Hassel, G. E., Herbst, E., & Garrod, R. T. 2008, ApJ, 681, 1385

    work page 2008

Show all 36 references
  1. [9]

    2004, ApJ, 617, 399

    Hirota, T., Maezawa, H., & Yamamoto, S. 2004, ApJ, 617, 399

    2004

  2. [10]

    1998, ApJ, 503, 717

    Hirota, T., Yamamoto, S., Mikami, H., & Ohishi, M. 1998, ApJ, 503, 717

    1998

  3. [11]

    L., & Moore, M

    Hudson, R. L., & Moore, M. H. 2018, ApJ, 857, 89

    2018

  4. [12]

    2004, PASJ, 56, 69 Kauffmann, J., Bertoldi, F., Bourke, T

    Kaifu, N., Ohishi, M., Kawaguchi, K., et al. 2004, PASJ, 56, 69 Kauffmann, J., Bertoldi, F., Bourke, T. L., Evans, N. J., II, & Lee, C. W. 2008, A&A, 487, 993 Kauffmann, J., Goldsmith, P. F., Melnick, G., et al. 2017, A&A, 605, L5

    2004

  5. [13]

    Armentrout, P. B. 1984, ApJ, 277, 581

    1984

  6. [14]

    1996, A&A, 311, 690

    Lee, H.-H., Herbst, E., Pineau des Forets, G., Roueff, E., & Le Bourlot, J. 1996, A&A, 311, 690

    1996

  7. [15]

    N., Visser, R., et al

    Li, X., Heays, A. N., Visser, R., et al. 2013, A&A, 555, A14

    2013

  8. [16]

    J., et al

    McElroy, D., Walsh, C., Markwick, A. J., et al. 2013, A&A, 550, A36

    2013

  9. [17]

    N., Savage, C., Brewster, M

    Milam, S. N., Savage, C., Brewster, M. A., Ziurys, L. M., & Wyckoff, S. 2005, ApJ, 634, 1126 M¨ uller, H. S. P., Schl¨ oder, F., Stutzki, J., & Winnewisser, G. 2005, Journal of Molecular Structure, 742, 215

    2005

  10. [18]

    M., Tafalla, M., et al

    Padovani, M., Walmsley, C. M., Tafalla, M., et al. 2009, A&A, 505, 1199

    2009

  11. [19]

    2013, A&A, 550, A38

    Palmeirim, P., Andr´ e, P., Kirk, J., et al. 2013, A&A, 550, A38

    2013

  12. [20]

    2016, MNRAS, 459, 3756

    Ruaud, M., Wakelam, V., & Hersant, F. 2016, MNRAS, 459, 3756

    2016

  13. [21]

    2007, ApJ, 663, 1174

    Sakai, N., Ikeda, M., Morita, M., et al. 2007, ApJ, 663, 1174

    2007

  14. [22]

    2013, Journal of Physical Chemistry A, 117, 9831

    Sakai, N., Takano, S., Sakai, T., et al. 2013, Journal of Physical Chemistry A, 117, 9831

    2013

  15. [23]

    2010, A&A, 512, A31

    Yamamoto, S. 2010, A&A, 512, A31

    2010

  16. [24]

    2013, Chemical Reviews, 113, 8981 13C Isotopic Fractionation of CCH in Two Starless Cores: L1521 B and L134N 15

    Sakai, N., & Yamamoto, S. 2013, Chemical Reviews, 113, 8981 13C Isotopic Fractionation of CCH in Two Starless Cores: L1521 B and L134N 15

    2013

  17. [25]

    N., & Herbst, E

    Shingledecker, C. N., & Herbst, E. 2018, Physical Chemistry Chemical Physics (Incorporating Faraday Transactions), 20, 5359 Spielfiedel, A., Feautrier, N., Najar, F., et al. 2012, MNRAS, 421, 1891

    2018

  18. [26]

    1992, ApJ, 392, 551

    Suzuki, H., Yamamoto, S., Ohishi, M., et al. 1992, ApJ, 392, 551

    1992

  19. [27]

    1998, A&A, 329, 1156

    Takano, S., Masuda, A., Hirahara, Y., et al. 1998, A&A, 329, 1156

    1998

  20. [28]

    1990, ApJL, 361, L15

    Takano, S., Suzuki, H., Ohishi, M., et al. 1990, ApJL, 361, L15

    1990

  21. [29]

    2019a, arXiv e-prints, arXiv:1906.11296

    Taniguchi, K., Herbst, E., Caselli, P., et al. 2019a, arXiv e-prints, arXiv:1906.11296

    1906 arXiv

  22. [30]

    2017, ApJ, 846, 46

    Taniguchi, K., Ozeki, H., & Saito, M. 2017, ApJ, 846, 46

    2017

  23. [31]

    2017, PASJ, 69, L7

    Taniguchi, K., & Saito, M. 2017, PASJ, 69, L7

    2017

  24. [32]

    K., & Minamidani, T

    Taniguchi, K., Saito, M., Sridharan, T. K., & Minamidani, T. 2018, ApJ, 854, 133

    2018

  25. [33]

    K., & Minamidani, T

    Taniguchi, K., Saito, M., Sridharan, T. K., & Minamidani, T. 2019b, ApJ, 872, 154 van der Tak, F. F. S., Black, J. H., Sch¨ oier, F. L., Jansen, D. J., & van Dishoeck, E. F. 2007, A&A, 468, 627

    2007

  26. [34]

    F., & Black, J

    Visser, R., van Dishoeck, E. F., & Black, J. H. 2009, A&A, 503, 323

    2009

  27. [35]

    2006, A&A, 451, 551

    Wakelam, V., Herbst, ER., & Selsis, F. 2006, A&A, 451, 551

    2006

  28. [36]

    Woon, D. E. 1995, Chemical Physics Letters, 244, 45

    1995

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