The interstellar chemistry of H<sub>2</sub>C<sub>3</sub>O isomers

Loison, Jean‐Christophe; Agúndez, M.; Marcelino, N.; Wakelam, Valentine; Hickson, Kevin M.; Cernicharo, J.; Gérin, M.; Roueff, E.; Guèlin, M.

doi:10.1093/mnras/stv2866

Cited by 72 publications

(78 citation statements)

References 75 publications

(126 reference statements)

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“…Therefore, the abundance ratio of the two isomers has most likely an origin based on kinetics over a simple thermal equilibrium. A similar conclusion was obtained by Loomis et al (2015) and Loison et al (2016) based on observations of the isomers of C 3 H 2 O, whose abundance ratios are not consistent with the minimum energy principle.…”

Section: Discussionsupporting

confidence: 74%

Rotational spectroscopy, tentative interstellar detection, and chemical modeling of N-methylformamide

Беллоче

Meshcheryakov

Garrod

et al. 2017

A&A

156

261

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Context. N-methylformamide, CH 3 NHCHO, may be an important molecule for interstellar pre-biotic chemistry because it contains a peptide bond, which in terrestrial chemistry is responsible for linking amino acids in proteins. The rotational spectrum of the most stable trans conformer of N-methylformamide is complicated by strong torsion-rotation interaction due to the low barrier of the methyl torsion. For this reason, the theoretical description of the rotational spectrum of the trans conformer has up to now not been accurate enough to provide a firm basis for its interstellar detection. Aims. In this context, as a prerequisite for a successful interstellar detection, our goal is to improve the characterization of the rotational spectrum of N-methylformamide. Methods. We use two absorption spectrometers in Kharkiv and Lille to measure the rotational spectra over the frequency range 45-630 GHz. The analysis is carried out using the Rho-axis method and the RAM36 code. We search for N-methylformamide toward the hot molecular core Sagittarius (Sgr) B2(N2) using a spectral line survey carried out with the Atacama Large Millimeter/submillimeter Array (ALMA). The astronomical spectra are analyzed under the assumption of local thermodynamic equilibrium. The astronomical results are put into a broader astrochemical context with the help of a gas-grain chemical kinetics model. Results. The new laboratory data set for the trans conformer of N-methylformamide consists of 9469 distinct line frequencies with J ≤ 62, including the first assignment of the rotational spectra of the first and second excited torsional states. All these lines are fitted within experimental accuracy for the first time. Based on the reliable frequency predictions obtained in this study, we report the tentative detection of N-methylformamide towards Sgr B2(N2). We find N-methylformamide to be more than one order of magnitude less abundant than formamide (NH 2 CHO), a factor of two less abundant than the unsaturated molecule methyl isocyanate (CH 3 NCO), but only slightly less abundant than acetamide (CH 3 CONH 2 ). We also report the tentative detection of the 15 N isotopologue of formamide ( 15 NH 2 CHO) toward Sgr B2(N2). The chemical models indicate that the efficient formation of HNCO via NH + CO on grains is a necessary step in the achievement of the observed gas-phase abundance of CH 3 NCO. Production of CH 3 NHCHO may plausibly occur on grains either through the direct addition of functional-group radicals or through the hydrogenation of CH 3 NCO. Conclusions. Provided the detection of N-methylformamide is confirmed, the only slight underabundance of this molecule compared to its more stable structural isomer acetamide and the sensitivity of the model abundances to the chemical kinetics parameters suggest that the formation of these two molecules is controlled by kinetics rather than thermal equilibrium.

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Section: Discussionsupporting

confidence: 74%

Rotational spectroscopy, tentative interstellar detection, and chemical modeling of N-methylformamide

Беллоче

Meshcheryakov

Garrod

et al. 2017

A&A

156

261

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“…A cold complex chemistry was discovered in B1-b via the detections of CH 3 OH, HCOOCH 3 , CH 3 CHO, trans-HCOOH, C 4 H, HNCO, and the H 2 C 3 O isomers (Sakai et al 2009a;Öberg et al 2010;López-Sepulcre et al 2015;Cuadrado et al 2016;Loison et al 2016), and tentatively CH 3 OCH 3 (Öberg et al 2010), as well as CH 3 O (Cernicharo et al 2012). These previous detections were all reported at levels well below the noise level obtained in our observations.…”

Section: B1-bsupporting

confidence: 54%

Deep, Broadband Spectral Line Surveys of Molecule-rich Interstellar Clouds

Weaver

Laas

Zou

et al. 2017

ApJS

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Spectral line surveys are an indispensable tool for exploring the physical and chemical evolution of astrophysical environments due to the vast amount of data that can be obtained in a relatively short amount of time. We present deep, broadband spectral line surveys of 30 interstellar clouds using two broadband λ=1.3 mm receivers at the Caltech Submillimeter Observatory. This information can be used to probe the influence of physical environment on molecular complexity. We observed a wide variety of sources to examine the relative abundances of organic molecules as they relate to the physical properties of the source (i.e., temperature, density, dynamics, etc.). The spectra are highly sensitive, with noise levels 25 mK at a velocity resolution of ∼0.35kms −1 . In the initial analysis presented here, column densities and rotational temperatures have been determined for the molecular species that contribute significantly to the spectral line density in this wavelength regime. We present these results and discuss their implications for complex molecule formation in the interstellar medium.

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“…Thus, in this case, the HC n O radicals would have both a grain-surface and a gas-phase origin. However, the non-detection of the propynonyl radical (HC 3 O) in TMC-1 (McGuire et al 2017a), and consistently negative results from searches for propadienone (H 2 C 3 O) in molecular clouds, including TMC-1 (Irvine et al 1988;Brown et al 1992;Loison et al 2016), tend to strongly disfavor this scenario.…”

Section: Resultsmentioning

confidence: 99%

Deep K-band Observations of TMC-1 with the Green Bank Telescope: Detection of HC₇O, Nondetection of HC₁₁N, and a Search for New Organic Molecules

Cordiner

Charnley²,

Kisiel

et al. 2017

ApJ

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The 100 m Robert C. Byrd Green Bank Telescope K-band (KFPA) receiver was used to perform a highsensitivity search for rotational emission lines from complex organic molecules in the cold interstellar medium towards TMC-1 (cyanopolyyne peak), focussing on the identification of new carbon-chain-bearing species as well as molecules of possible prebiotic relevance. We report a detection of the carbon-chain oxide species HC 7 O and derive a column density of (7.8 ± 0.9) × 10 11 cm −2 . This species is theorized to form as a result of associative electron detachment reactions between oxygen atoms and C 7 H − , and/or reaction of C 6 H 2 + with CO (followed by dissociative electron recombination). Upper limits are given for the related HC 6 O, C 6 O and C 7 O molecules. In addition, we obtained the first detections of emission from individual 13 C isotopologues of HC 7 N, and derive abundance ratios HC 7 N/HCCC 13 CCCCN = 110 ± 16 and HC 7 N/HCCCC 13 CCCN = 96 ± 11, indicative of significant 13 C depletion in this species relative to the local interstellar elemental 12 C/ 13 C ratio of 60-70. The observed spectral region covered two transitions of HC 11 N, but emission from this species was not detected, and the corresponding column density upper limit is 7.4 × 10 10 cm −2 (at 95% confidence). This is significantly lower than the value of 2.8 × 10 11 cm −2 previously claimed by Bell et al. (1997) and confirms the recent non-detection of HC 11 N in TMC-1 by Loomis et al. (2016). Upper limits were also obtained for the column densities of malononitrile and the nitrogen heterocycles quinoline, isoquinoline and pyrimidine.

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The interstellar chemistry of H₂C₃O isomers

Cited by 72 publications

References 75 publications

Rotational spectroscopy, tentative interstellar detection, and chemical modeling of N-methylformamide

Rotational spectroscopy, tentative interstellar detection, and chemical modeling of N-methylformamide

Deep, Broadband Spectral Line Surveys of Molecule-rich Interstellar Clouds

Deep K-band Observations of TMC-1 with the Green Bank Telescope: Detection of HC₇O, Nondetection of HC₁₁N, and a Search for New Organic Molecules

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The interstellar chemistry of H2C3O isomers

Cited by 72 publications

References 75 publications

Rotational spectroscopy, tentative interstellar detection, and chemical modeling of N-methylformamide

Rotational spectroscopy, tentative interstellar detection, and chemical modeling of N-methylformamide

Deep, Broadband Spectral Line Surveys of Molecule-rich Interstellar Clouds

Deep K-band Observations of TMC-1 with the Green Bank Telescope: Detection of HC7O, Nondetection of HC11N, and a Search for New Organic Molecules

Contact Info

Product

Resources

About

The interstellar chemistry of H₂C₃O isomers

Deep K-band Observations of TMC-1 with the Green Bank Telescope: Detection of HC₇O, Nondetection of HC₁₁N, and a Search for New Organic Molecules