Detection of the aromatic molecule benzonitrile (
 c
 -C
 6
 H
 5
 CN) in the interstellar medium

McGuire, Brett A.; Burkhardt, Andrew M.; Kalenskii, S. V.; Shingledecker, Christopher N.; Remijan, Anthony J.; Herbst, Eric; McCarthy, Michael

doi:10.1126/science.aao4890

Cited by 452 publications

(324 citation statements)

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“…Most previous searches have involved targeting molecules in which the heteroatom, specifically N, is incorporated in an aromatic ring. While our derived abundance of pyrimidine is not particularly restrictive with regard to its possible presence in TMC-1, the recent detection of benzonitrile in TMC-1 by McGuire et al (2017b) and of toluene in comet 67P/Churyumov-Gerasimenko Altwegg et al (2017) suggests that interstellar chemistry may favor the presence of heteroatoms as functional side-groups, rather than within the ring structure. Future deep searches in TMC-1 with the GBT should provide further insights into the inventory of the heaviest interstellar molecules.…”

Section: Nitrogen Heterocyclesmentioning

confidence: 75%

“…The first detection of benzonitrile (C 6 H 5 CN) has also been submitted for publication (McGuire et al 2017b) In this paper we report detections and column densities for HC 7 O and two isotopologues of HC 7 N. We also report nondetections of HC 11 N, HC 6 O, C 6 O, C 7 O, malononitrile, quinoline, isoquinoline and pyrimidine, for which column density upper limits are presented.…”

Section: Introductionmentioning

confidence: 85%

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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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Section: Nitrogen Heterocyclesmentioning

confidence: 75%

Section: Introductionmentioning

confidence: 85%

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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“…Recent improvements in efficiencies of radio telescopes enable the achievement of high sensitivities with high angular resolution within reasonable observing times. Owing to such developments, we can detect molecules with abundances significantly lower than previously detected species (e.g., McGuire et al 2018), including isotopologues (Taniguchi et al 2016a;Burkhardt et al 2018). The discovery of these molecules in various evolutionary stages raises new challenges in the fields of chemical network simulation and laboratory experiment.…”

Section: Introductionmentioning

confidence: 99%

Cyanopolyyne Chemistry around Massive Young Stellar Objects

Taniguchi

Herbst

Caselli

et al. 2019

ApJ

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Recent radio astronomical observations have revealed that HC 5 N, the second shortest cyanopolyyne (HC 2n+1 N), is abundant around some massive young stellar objects (MYSOs), which is not predicted by classical carbon-chain chemistry. For example, the observed HC 5 N abundance toward the G28.28−0.36 MYSO is higher than that in L1527, which is one of the warm carbon chain chemistry (WCCC) sources, by more than one order of magnitude . In this paper, we present chemical simulations of hot-core models with a warm-up period using the astrochemical code Nautilus. We find that the cyanopolyynes are formed initially in the gas phase and accreted onto the bulk and surface of granular ice mantles during the lukewarm phase, which occurs at 25 < T < 100 K. In slow warm-up period models, the peak abundances occur as the cyanopolyynes desorb from dust grains after the temperature rises above 100 K. The lower limits of the abundances of HC 5 N, CH 3 CCH, and CH 3 OH observed in the G28.28−0.36 MYSO can be reproduced in our hot-core models, after their desorption from dust grains. Moreover, previous observations suggested chemical diversity in envelopes around different MYSOs. We discuss possible interpretations of relationships between stages of the star-formation process and such chemical diversity, such as the different warm-up timescales. This timescale depends not only on the mass of central stars but also on the relationship between the size of warm regions and their infall velocity.

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“…Since then, many cyanide species have been found, including vinyl cyanide (C 2 H 3 CN; Gardner & Winnewisser 1975), ethyl cyanide (C 2 H 5 CN; Johnson et al 1977), n-propyl cyanide (n-C 3 H 7 CN; Belloche et al 2009) and i-propyl cyanide (i-C 3 H 7 CN, a branched species; Belloche et al 2014). Most recently, benzonitrile (c-C 6 H 5 CN; McGuire et al 2017), the first benzenederived aromatic molecule detected in the ISM through radio astronomy was seen towards the dark cloud TMC-1.…”

Section: Introductionmentioning

confidence: 99%

Exploring molecular complexity with ALMA (EMoCA): complex isocyanides in Sgr B2(N)

Willis

Garrod

Беллоче

et al. 2020

A&A

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Context. The Exploring Molecule Complexity with ALMA (EMoCA) survey is an imaging spectral line survey using the Atacama Large Millimeter/submillimeter Array (ALMA) to study the hot-core complex Sagittarius B2(N). Recently, EMoCA revealed the presence of three new hot cores in this complex (N3-N5), in addition to providing detailed spectral data on the previously known hot cores in the complex (N1 and N2). The present study focuses on N2, which is a rich and interesting source for the study of complex molecules whose narrow line widths ameliorate the line confusion problem. Aims. We investigate the column densities and excitation temperatures of cyanide and isocyanide species in Sgr B2(N2). We then use state-of-the-art chemical models to interpret these observed quantities. We also investigate the effect of varying the cosmic-ray ionization rate (ζ) on the chemistry of these molecules. Methods. We used the EMoCA survey data to search for isocyanides in Sgr B2(N2) and their corresponding cyanide analogs. We then used the coupled three-phase chemical kinetics code MAGICKAL to simulate their chemistry. Several new species, and over 100 new reactions have been added to the network. In addition, a new single-stage simultaneous collapse/warm-up model has been implemented, thus eliminating the need for the previous two-stage models. A variable, visual extinction-dependent ζ was also incorporated into the model and tested. Results. We report the tentative detection of CH 3 NC and HCCNC in Sgr B2(N2), which represents the first detection of both species in a hot core of Sgr B2. In addition, we calculate new upper limits for C 2 H 5 NC, C 2 H 3 NC, HNC 3 , and HC 3 NH + . Our updated chemical models can reproduce most observed NC:CN ratios reasonably well depending on the physical parameters chosen. The model that performs best has an extinction-dependent cosmic-ray ionization rate that varies from ∼2 × 10 −15 s −1 at the edge of the cloud to ∼1 × 10 −16 s −1 in the center. Models with higher extinction-dependent ζ than this model generally do not agree as well, nor do models with a constant ζ greater than the canonical value of 1.3 × 10 −17 s −1 throughout the source. Radiative transfer models are run using results of the best-fit chemical model. Column densities produced by the radiative transfer models are significantly lower than those determined observationally. Inaccuracy in the observationally determined density and temperature profiles is a possible explanation. Excitation temperatures are well reproduced for the true "hot core" molecules, but are more variable for other molecules such as HC 3 N, for which fewer lines exist in ALMA Band 3. Conclusions. The updated chemical models do a very good job of reproducing the observed abundances ratio of CH 3 NC:CH 3 CN towards Sgr B2(N2), while being consistent with upper limits for other isocyanide/cyanide pairs. HCCNC:HC 3 N is poorly reproduced, however. Our results highlight the need for models with A V -depdendent ζ. However, there is still much to be understood about...

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Detection of the aromatic molecule benzonitrile ( c -C ₆ H ₅ CN) in the interstellar medium

Cited by 452 publications

References 56 publications

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

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

Cyanopolyyne Chemistry around Massive Young Stellar Objects

Exploring molecular complexity with ALMA (EMoCA): complex isocyanides in Sgr B2(N)

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Detection of the aromatic molecule benzonitrile ( c -C 6 H 5 CN) in the interstellar medium

Cited by 452 publications

References 56 publications

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

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

Cyanopolyyne Chemistry around Massive Young Stellar Objects

Exploring molecular complexity with ALMA (EMoCA): complex isocyanides in Sgr B2(N)

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Product

Resources

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Detection of the aromatic molecule benzonitrile ( c -C ₆ H ₅ CN) in the interstellar medium

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

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