Microwave spectra of propyne and its [13C] isotopic species

Dubrulle, A.; Boucher, D.; Burie, J.; Demaison, J.

doi:10.1016/0022-2852(78)90051-6

Cited by 53 publications

(28 citation statements)

References 14 publications

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“…We use the CDMS entry for the vibrational ground state (Cazzoli & Puzzarini 2008) and first excited state 10 = 1 (Müller et al 2002) of the main isotopologue (tag 40 502 version 3, 40 504 version 1), and the JPL entries for the 13 C isotopologues (tags 41 002, 41 003, and 41 004, all version 1) which are based on Dubrulle et al (1978) 11 . Sgr B2(N): the parameters of all entries related to propyne are listed in Table 19.…”

Section: Propyne Ch 3 Cchmentioning

confidence: 99%

Complex organic molecules in the interstellar medium: IRAM 30 m line survey of Sagittarius B2(N) and (M)

Беллоче

Müller

Menten

et al. 2013

A&A

385

523

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Context. The discovery of amino acids in meteorites fallen to Earth and the detection of glycine, the simplest of them, in samples returned from a comet to Earth strongly suggest that the chemistry of the interstellar medium is capable of producing such complex organic molecules and that they may be widespread in our Galaxy. Aims. Our goal is to investigate the degree of chemical complexity that can be reached in the interstellar medium, in particular in dense star-forming regions. Methods. We performed an unbiased, spectral line survey toward Sgr B2(N) and (M), two regions where high-mass stars are formed, with the IRAM 30 m telescope in the 3 mm atmospheric transmission window. Partial surveys at 2 and 1.3 mm were performed in parallel. The spectra were analyzed with a simple radiative transfer model that assumes local thermodynamic equilibrium but takes optical depth effects into account. Results. About 3675 and 945 spectral lines with a peak signal-to-noise ratio higher than 4 are detected at 3 mm toward Sgr B2(N) and (M), i.e. about 102 and 26 lines per GHz, respectively. This represents an increase by about a factor of two over previous surveys of Sgr B2. About 70% and 47% of the lines detected toward Sgr B2(N) and (M) are identified and assigned to 56 and 46 distinct molecules as well as to 66 and 54 less abundant isotopologues of these molecules, respectively. In addition, we report the detection of transitions from 59 and 24 catalog entries corresponding to vibrationally or torsionally excited states of some of these molecules, respectively, up to a vibration energy of 1400 cm −1 (2000 K). Excitation temperatures and column densities were derived for each species but should be used with caution. The rotation temperatures of the detected complex molecules typically range from ∼50 to 200 K. Among the detected molecules, aminoacetonitrile, n-propyl cyanide, and ethyl formate were reported for the first time in space based on this survey, as were five rare isotopologues of vinyl cyanide, cyanoacetylene, and hydrogen cyanide. We also report the detection of transitions from within twelve new vibrationally or torsionally excited states of known molecules. Absorption features produced by diffuse clouds along the line of sight are detected in transitions with low rotation quantum numbers of many simple molecules and are modeled with ∼30-40 velocity components with typical linewidths of ∼3-5 km s −1 . Conclusions. Although the large number of unidentified lines may still allow future identification of new molecules, we expect most of these lines to belong to vibrationally or torsionally excited states or to rare isotopologues of known molecules for which spectroscopic predictions are currently missing. Significant progress in extending the inventory of complex organic molecules in Sgr B2(N) and deriving tighter constraints on their location, origin, and abundance is expected in the near future thanks to an ongoing spectral line survey at 3 mm with ALMA in its cycles 0 and 1. The present single-dish surve...

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Section: Propyne Ch 3 Cchmentioning

confidence: 99%

Complex organic molecules in the interstellar medium: IRAM 30 m line survey of Sagittarius B2(N) and (M)

Беллоче

Müller

Menten

et al. 2013

A&A

385

523

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“…The JPL database entries were used in the analysis of the three observed isotopologues of methylacetylene CH 3 CCH (or propyne: 040001, 041004, and 41002, all ver. 1; Pickett et al 1998), all based on the experiment work of Dubrulle et al (1978). Because of two velocity components and a ∼10 km s −1 line width, lower value K components were typically blended to create a single asymmetric feature for all three species, see Figure 1(a).…”

Section: Two Distinct Lines Of H Cs 2 13mentioning

confidence: 99%

The ¹²C/¹³C Ratio in Sgr B2(N): Constraints for Galactic Chemical Evolution and Isotopic Chemistry

Halfen

Woolf

Ziurys

2017

ApJ

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A study has been conducted of 12 C/ 13 C ratios in five complex molecules in the Galactic center. H 2 CS, CH 3 CCH, NH 2 CHO, CH 2 CHCN, and CH 3 CH 2 CN and their 13 C-substituted species have been observed in numerous transitions at 1, 2, and 3 mm, acquired in a spectral-line survey of Sgr B2(N), conducted with the telescopes of the Arizona Radio Observatory (ARO). Between 22 and 54 individual, unblended lines for the 12 C species and 2-54 for 13 C-substituted analogs were modeled in a global radiative transfer analysis. All five molecules were found to consistently exhibit two velocity components near V LSR ∼ 64 and 73 km s −1 , with column densities ranging from N tot ∼ 3 × 10 14 −4 × 10 17 cm −2 and ∼2 × 10 13 −1 × 10 17 cm −2 for the 12 C and 13 C species, respectively. Based on 14 different isotopic combinations, ratios were obtained in the range 12 C/ 13 C = 15±5 to 33±13, with an average value of 24±7, based on comparison of column densities. These measurements better anchor the 12 C/ 13 C ratio at the Galactic center, and suggest a slightly revised isotope gradient of 12 C/ 13 C = 5.21(0.52) D GC + 22.6(3.3). As indicated by the column densities, no preferential 13 C enrichment was found on the differing carbon sites of CH 3 CCH, CH 2 CHCN, and CH 3 CH 2 CN. Because of the elevated temperatures in Sgr B2(N), 13 C isotopic substitution is effectively "scrambled," diminishing chemical fractionation effects. The resulting ratios thus reflect stellar nucleosynthesis and Galactic chemical evolution, as is likely the case for most warm clouds.

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“…where k is the Boltzmann constant, η ν the beam filling factor, ν the line rest frequency, S the line strength, g i the statistical weight, and µ = 0.75 Debye (Dubrulle et al 1978) the dipole moment of the CH 3 C 2 H molecule. In Table 7 we give the rotational temperatures (T rot ) and total CH 3 C 2 H source column densities (N tot ): these have been obtained from a least square fit to the data, as shown in the "Boltzmann plots" in Fig.…”

Section: Temperature and Column Densitymentioning

confidence: 99%

“…The CH 3 C 2 H species is especially suitable to our purposes. This is a symmetric-top molecule (see Townes & Schawlow 1975) with a small dipole moment (µ = 0.75 Debye, Dubrulle et al 1978), which makes thermalisation easy even at densities as low as 10 4 cm −3 . We thus expect CH 3 C 2 H to be in "local thermodynamical equilibrium" (LTE) conditions in the clumps found by Cesaroni et al (1991) around the UC Hii regions.…”

Section: Introductionmentioning

confidence: 99%

The structure of molecular clumps around high-mass young stellar objects

Fontani

Cesaroni

Caselli

et al. 2002

A&A

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Abstract.We have used the IRAM 30-m and FCRAO 14-m telescopes to observe the molecular clumps associated with 12 ultracompact (UC) Hii regions in the J = 6−5, 8-7 and 13-12 rotational transitions of methyl-acetylene (CH3C2H). Under the assumption of LTE and optically thin emission, we have derived temperature estimates ranging from 30 to 56 K. We estimate that the clumps have diameters of 0.2-1.6 pc, H2 densities of 10 5 -10 6 cm −3 , and masses of 10 2 -2 × 10 4 M . We compare these values with those obtained by other authors from different molecular tracers and find that the H2 density and the temperature inside the clumps vary respectively like nH 2 ∝ R −2.6 and T ∝ R −0.5 , with R distance from the centre. We also find that the virial masses of the clumps are ∼3 times less than those derived from the CH3C2H column densities: we show that a plausible explanation is that magnetic fields play an important role to stabilise the clumps, which are on the verge of gravitational collapse. Finally, we show that the CH3C2H line width increases for decreasing distance from the clump centre: this effect is consistent with infall in the inner regions of the clumps. We conclude that the clumps around UC Hii regions are likely to be transient (∼10 5 yr) entities, remnants of isothermal spheres currently undergoing gravitational collapse: the high mass accretion rates (∼10 −2 M yr −1 ) lead to massive star formation at the centre of such clumps.

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Microwave spectra of propyne and its [13C] isotopic species

Cited by 53 publications

References 14 publications

Complex organic molecules in the interstellar medium: IRAM 30 m line survey of Sagittarius B2(N) and (M)

Complex organic molecules in the interstellar medium: IRAM 30 m line survey of Sagittarius B2(N) and (M)

The ¹²C/¹³C Ratio in Sgr B2(N): Constraints for Galactic Chemical Evolution and Isotopic Chemistry

The structure of molecular clumps around high-mass young stellar objects

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Microwave spectra of propyne and its [13C] isotopic species

Cited by 53 publications

References 14 publications

Complex organic molecules in the interstellar medium: IRAM 30 m line survey of Sagittarius B2(N) and (M)

Complex organic molecules in the interstellar medium: IRAM 30 m line survey of Sagittarius B2(N) and (M)

The 12C/13C Ratio in Sgr B2(N): Constraints for Galactic Chemical Evolution and Isotopic Chemistry

The structure of molecular clumps around high-mass young stellar objects

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The ¹²C/¹³C Ratio in Sgr B2(N): Constraints for Galactic Chemical Evolution and Isotopic Chemistry