Rotational spectroscopy of isotopic vinyl cyanide, H2CCHCN, in the laboratory and in space

Müller, H. S. P.; Беллоче, А.; Menten, K. M.; Comito, C.; Schilke, P.

doi:10.1016/j.jms.2008.03.016

Cited by 69 publications

(90 citation statements)

References 31 publications

(142 reference statements)

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“…For a source size of 3 , this translates into a column density of 2.9 × 10 17 cm −2 , which is a factor 4 smaller than the column density we derive for the main velocity component. However, our model predicts peak line opacities of 4−6 for these transitions, which is supported by our simultaneous modeling of the 13 C isotopologues of ethyl cyanide (see Müller et al 2008). As a result, Liu et al (2001) most likely underestimated the column densities of ethyl cyanide by a factor of a few, which reconciles the single-dish and interferometric measurements and confirms that the source of ethyl cyanide emission is compact.…”

Section: Comparison To Related Speciessupporting

confidence: 82%

Increased complexity in interstellar chemistry: detection and chemical modeling of ethyl formate andn-propyl cyanide in Sagittarius B2(N)

Беллоче

Garrod

Müller

et al. 2009

A&A

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Context. In recent years, organic molecules of increasing complexity have been found toward the prolific Galactic center source Sagittarius B2. Aims. We wish to explore the degree of complexity that the interstellar chemistry can reach in star-forming regions. Methods. We carried out a complete line survey of the hot cores Sgr B2(N) and (M) with the IRAM 30 m telescope in the 3 mm range, plus partial surveys at 2 and 1.3 mm. We analyzed this spectral survey in the local thermodynamical equilibrium approximation. We modeled the emission of all known molecules simultaneously, which allows us to search for less abundant, more complex molecules. We compared the derived column densities with the predictions of a coupled gas-phase and grain-surface chemical code.Results. We report the first detection in space of ethyl formate (C 2 H 5 OCHO) and n-propyl cyanide (C 3 H 7 CN) toward Sgr B2(N). The detection of n-propyl cyanide is based on refined spectroscopic parameters derived from combined analyses of available laboratory spectroscopic data. For each molecule, we identified spectral features at the predicted frequencies having intensities compatible with a unique rotation temperature. For an assumed source size of 3 , our modeling yields a column density of 5.4 × 10 16 cm −2 , a temperature of 100 K, and a linewidth of 7 km s −1 for ethyl formate. n-Propyl cyanide is detected with two velocity components having column densities of 1.5 × 10 16 cm −2 and 6.6 × 10 15 cm −2 , respectively, for a source size of 3 , a temperature of 150 K, and a linewidth of 7 km s −1 . The abundances of ethyl formate and n-propyl cyanide relative to H 2 are estimated to be 3.6 × 10 −9 and 1.0 × 10 −9 , respectively. We derived column density ratios of 0.8/15/1 for the related species t-HCOOH/CH 3 OCHO/C 2 H 5 OCHO and 108/80/1 for CH 3 CN/C 2 H 5 CN/C 3 H 7 CN. Our chemical modeling reproduces these ratios reasonably well. It suggests that the sequential, piecewise construction of ethyl and n-propyl cyanide from their constituent functional groups on the grain surfaces is their most likely formation route. Ethyl formate is primarily formed on the grains by adding CH 3 to functional-group radicals derived from methyl formate, although ethanol may also be a precursor. Conclusions. The detection in Sgr B2(N) of the next stage of complexity in two classes of complex molecule, esters and alkyl cyanides, suggests that greater complexity in other classes of molecule may be present in the interstellar medium.

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Section: Comparison To Related Speciessupporting

confidence: 82%

Increased complexity in interstellar chemistry: detection and chemical modeling of ethyl formate andn-propyl cyanide in Sagittarius B2(N)

Беллоче

Garrod

Müller

et al. 2009

A&A

242

300

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“…Quite commonly, we reach relative accuracies of 10 −8 or even slightly better (Müller & Brünken 2005;Müller et al 2007aMüller et al , 2008. Müller et al (2000) have shown that similar accuracies can be achieved for the rare isotopolog SO 17 O in a rather dense spectrum.…”

Section: Methodsmentioning

confidence: 58%

“…This species should be observable fairly readily in Galactic center sources because of the 12 C/ 13 C ratio of about 20 in these sources (Wilson & Rood 1994;Müller et al 2008). Hence, lines of the doubly substituted 13 C isotopolog should be only slightly weaker than those of CH 3 C 15 N. In fact, inspection of the 3 mm line survey of Sagittarius B2(N) obtained with the IRAM 30 m telecope (Belloche, private communication, 2008; see also Belloche et al 2009;Müller et al 2008) revealed that several 13 CH 13 3 CN lines should have S/N ratios of greater than three. However, all lines were overlapped by stronger lines, frequently belonging to the much stronger 13 CH 3 CN which has fairly similar spectroscopic parameters.…”

Section: Ch 13 3 Cnmentioning

confidence: 99%

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Rotational spectra of isotopic species of methyl cyanide, CH₃CN, in their ground vibrational states up to terahertz frequencies

Müller¹,

Drouin

Pearson

2009

A&A

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Context. Methyl cyanide is an important trace molecule in star-forming regions. It is one of the more common molecules used to derive kinetic temperatures in such sources. Aims. As preparatory work for Herschel, SOFIA, and in particular ALMA we want to improve the rest frequencies of the main as well as minor isotopologs of methyl cyanide. Methods. The laboratory rotational spectrum of methyl cyanide in natural isotopic composition has been recorded up to 1.63 THz. Results. Transitions with good signal-to-noise ratio could be identified for CH 3 CN, 13 CH 3 CN, CH 13 3 CN, CH 3 C 15 N, CH 2 DCN, and 13 CH 13 3 CN in their ground vibrational states up to about 1.2 THz. The main isotopic species could be identified even in the highest frequency spectral recordings around 1.6 THz. The highest J quantum numbers included in the fit are 64 for 13 CH 13 3 CN and 89 for the main isotopic species. Greatly improved spectroscopic parameters have been obtained by fitting the present data together with previously reported transition frequencies.Conclusions. The present data will be helpful to identify isotopologs of methyl cyanide in the higher frequency bands of instruments such as the recently launched Herschel satellite, the upcoming airplane mission SOFIA or the radio telescope array ALMA.

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“…Details of this procedure for the Sgr B2(N) region have been given previously (Belloche et al 2008a(Belloche et al , 2009Müller et al 2008), whereas the model of Sgr B2(M) will be described elsewhere (Belloche et al, in preparation). Our LTE modeling assumes a very basic source structure, and the radiative transfer calculations are approximate.…”

Section: Astronomical Observations and Analysismentioning

confidence: 99%

Interstellar HOCN in the Galactic center region

Brünken¹,

Беллоче

Martín

et al. 2010

A&A

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Aims. Our aim is to confirm the interstellar detection of cyanic acid, HOCN, in the Galactic center clouds. It has previously been tentatively detected only in Sgr B2(OH). Methods. We used a complete line survey of the hot cores Sgr B2(N) and (M) in the 3 mm range, complemented by additional observations carried out with the IRAM 30 m telescope at selected frequencies in the 2 mm band and towards four additional positions in the Sgr B2 cloud complex in the 2 and 3 mm bands. The spectral survey was analysed in the local thermodynamical equilibrium approximation (LTE) by modeling the emission of all identified molecules simultaneously. This allowed us to distinguish weak features of HOCN from the rich line spectrum observed in Sgr B2(N) and (M). Lines of the more stable (by 1.1 eV) isomer isocyanic acid, HNCO, in these sources, as well as those of HOCN and HNCO towards the other positions, were analysed in the LTE approximation as well. Results. Four transitions of HOCN were detected in a quiescent molecular cloud in the Galactic center at a position offset in (RA, Dec) by (20 , 100 ) from the hot core source Sgr B2(M), confirming its previous tentative interstellar detection. Up to four transitions were detected toward five other positions in the Sgr B2 complex, including the hot cores Sgr B2(M), (S), and (N). A fairly constant abundance ratio of ∼0.3−0.8% for HOCN relative to HNCO was derived for the extended gas components, suggesting a common formation process of these isomers.

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Rotational spectroscopy of isotopic vinyl cyanide, H2CCHCN, in the laboratory and in space

Cited by 69 publications

References 31 publications

Increased complexity in interstellar chemistry: detection and chemical modeling of ethyl formate andn-propyl cyanide in Sagittarius B2(N)

Increased complexity in interstellar chemistry: detection and chemical modeling of ethyl formate andn-propyl cyanide in Sagittarius B2(N)

Rotational spectra of isotopic species of methyl cyanide, CH₃CN, in their ground vibrational states up to terahertz frequencies

Interstellar HOCN in the Galactic center region

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Rotational spectroscopy of isotopic vinyl cyanide, H2CCHCN, in the laboratory and in space

Cited by 69 publications

References 31 publications

Increased complexity in interstellar chemistry: detection and chemical modeling of ethyl formate andn-propyl cyanide in Sagittarius B2(N)

Increased complexity in interstellar chemistry: detection and chemical modeling of ethyl formate andn-propyl cyanide in Sagittarius B2(N)

Rotational spectra of isotopic species of methyl cyanide, CH3CN, in their ground vibrational states up to terahertz frequencies

Interstellar HOCN in the Galactic center region

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Rotational spectra of isotopic species of methyl cyanide, CH₃CN, in their ground vibrational states up to terahertz frequencies