A spectral-line survey of W51 from 17.6 to 22.0 GHz

Bell, Marvin; Avery, L. W.; Watson, J. K. G.

doi:10.1086/191776

Cited by 26 publications

(20 citation statements)

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“…The vibrational strength is l 2 fi with l fi defined in Eq. (37), and, finally, the partition function Q eff was set to 100. Q eff ¼ 100 can be viewed as a typical value of the rotation-vibration partition function, and so the value of I fi ðf iÞ is representative for the intensities of the individual rotation-vibration transitions of the vibrational band in question.…”

Section: Electric-dipole Transition Momentsmentioning

confidence: 99%

“…An important motivation for the present work is astrophysical: ammonia is found in comets, interstellar space, and planetary atmospheres [37][38][39]. Spectroscopic studies of NH 3 and related molecules lead to new understanding of these environments.…”

Section: Introductionmentioning

confidence: 99%

“…The NH 3 OPR can be determined by analysis of the emission spectrum of NH 2 which derives from the photodissociation of NH 3 [40][41][42]. Interstellar microwave transitions have already been observed for NH 3 [37]. In addition nitrogen-containing, tetra-atomic ions such as HCNH + [43] have been detected in interstellar space, and so NH þ 3 appears a probable candidate for interstellar detection.…”

Section: Introductionmentioning

confidence: 99%

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Ab initio potential energy surface, electric-dipole moment, polarizability tensor, and theoretical rovibrational spectra in the electronic ground state of

et al. 2008

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We report the calculation of a six-dimensional CCSD(T)/aug-cc-pVQZ potential energy surface for the electronic ground state of NH þ 3 together with the corresponding CCSD(T)/aug-cc-pVTZ dipole moment and polarizability surface of 14 NH þ 3 . These electronic properties have been computed on a large grid of molecular geometries. A number of newly calculated band centers are presented along with the associated electric-dipole transition moments. We further report the first calculation of vibrational matrix elements of the polarizability tensor components for 14 NH þ 3 ; these matrix elements determine the intensities of Raman transitions. In addition, the rovibrational absorption spectra of the m 2 , m 3 , m 4 , 2m 2 À m 2 , and m 2 þ m 3 À m 2 bands have been simulated.

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Section: Electric-dipole Transition Momentsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Ab initio potential energy surface, electric-dipole moment, polarizability tensor, and theoretical rovibrational spectra in the electronic ground state of

et al. 2008

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“…However, despite the long history of powerful large radio telescopes, few unbiased frequency surveys have been conducted in the cm-wave regime. A 4.4 GHz bandwidth survey from 17.6 to 22.0 GHz toward the massive star-forming region W51 has been reported by Bell et al (1993b) showing many previously unidentified lines. The dark cloud TMC-1 has been observed in selected bands from 4−6 and 8−10 GHz (Kalenskii et al 2004), as well as at 9−50 GHz (Kaifu et al 2004).…”

Section: Introductionmentioning

confidence: 99%

A 1.3 cm line survey toward IRC +10216

Gong

Henkel

Spezzano

et al. 2015

A&A

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Context. IRC +10216 is the prototypical carbon star exhibiting an extended molecular circumstellar envelope. Its spectral properties are therefore the template for an entire class of objects. Aims. The main goal is to systematically study the λ ∼ 1.3 cm spectral line characteristics of IRC +10216. Methods. We carried out a spectral line survey with the Effelsberg-100 m telescope toward IRC +10216. It covers the frequency range between 17.8 GHz and 26.3 GHz (K-band).Results. In the circumstellar shell of IRC +10216, we find 78 spectral lines, among which 12 remain unidentified. The identified lines are assigned to 18 different molecules and radicals. A total of 23 lines from species known to exist in this envelope are detected for the first time outside the solar system and there are additional 20 lines first detected in IRC +10216. The potential orgin of "U" lines is also discussed. Assuming local thermodynamic equilibrium (LTE), we then determine rotational temperatures and column densities of 17 detected molecules. Molecular abundances relative to H 2 are also estimated. A non-LTE analysis of NH 3 shows that the bulk of its emission arises from the inner envelope with a kinetic temperature of 70 ± 20 K. Evidence for NH 3 emitting gas with higher kinetic temperature is also obtained, and potential abundance differences between various 13 C-bearing isotopologues of HC 5 N are evaluated. Overall, the isotopic 12 C/ 13 C ratio is estimated to be 49 ± 9. Finally, a comparison of detected molecules in the λ ∼ 1.3 cm range with the dark cloud TMC-1 indicates that silicate-bearing molecules are more predominant in IRC +10216.

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“…For W51M, 14 transitions were observed, with intensities from 0.047 to 0.18 K. The LSR velocities are typically V LSR = 56-58 km/s, canonical values for this source, and the linewidths fall in the range of 8-12 km/s, also typical (e.g., Bell et al, 1993). This cloud is a new source for NH 2 CHO.…”

Section: Resultsmentioning

confidence: 74%

Observations of Interstellar Formamide: Availability of a Prebiotic Precursor in the Galactic Habitable Zone

2013

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We conducted a study on interstellar formamide, NH 2 CHO, toward star-forming regions of dense molecular clouds, using the telescopes of the Arizona Radio Observatory (ARO). The Kitt Peak 12 m antenna and the Submillimeter Telescope (SMT) were used to measure multiple rotational transitions of this molecule between 100 and 250 GHz. Four new sources of formamide were found [W51M, M17 SW, G34.3, and DR21(OH)], and complementary data were obtained toward Orion-KL, W3(OH), and NGC 7538. From these observations, column densities for formamide were determined to be in the range of 1.1 · 10 12 to 9.1 · 10 13 cm -2 , with rotational temperatures of 70-177 K. The molecule is thus present in warm gas, with abundances relative to H 2 of 1 · 10 -11 to 1 · 10 -10 . It appears to be a common constituent of star-forming regions that foster planetary systems within the galactic habitable zone, with abundances comparable to that found in comet Hale-Bopp. Formamide's presence in comets and molecular clouds suggests that the compound could have been brought to Earth by exogenous delivery, perhaps with an infall flux as high as *0.1 mol/km 2 /yr or 0.18 mmol/m 2 in a single impact. Formamide has recently been proposed as a single-carbon, prebiotic source of nucleobases and nucleic acids. This study suggests that a sufficient amount of NH 2 CHO could have been available for such chemistry.

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A spectral-line survey of W51 from 17.6 to 22.0 GHz

Cited by 26 publications

References 0 publications

Ab initio potential energy surface, electric-dipole moment, polarizability tensor, and theoretical rovibrational spectra in the electronic ground state of

Ab initio potential energy surface, electric-dipole moment, polarizability tensor, and theoretical rovibrational spectra in the electronic ground state of

A 1.3 cm line survey toward IRC +10216

Observations of Interstellar Formamide: Availability of a Prebiotic Precursor in the Galactic Habitable Zone

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